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Friday, December 19, 2008

## Betty

I'm feeling a bit verklempt about having sold my beloved honda civic, Betty. The guy who bought her (a young jewish guy named Oren from Long Island) seemed really nice and he was SO excited to find a 4DR standard transmission civic.

I bought Betty new, for a bit under 14,000$in August of 1997 when I first moved to Hoboken. I didn't know how to drive standard transmission at the time, so the first few weeks were a bit rough. But she was patient with me, and within a few thousand miles we were getting along great. I really enjoyed my time alone with her --- driving to and from work was a time to prepare for the day, or recover from it. When she was feeling feisty we tried to set new speed records (23 minutes. I bet you can't beat that in a Porche!). On the weekends, she survived many a road trip, and she dutifully carried heaps of windsurfing equipment on her roof and in her trunk, and she never complained. The most amazing thing about Betty was how reliable she was. Even after 175,000 miles, really nothing had gone ever wrong with her. Two flat tires, occassional new muffler, and two broken windshields from rocks being thrown up at me by trucks, but nothing worse than that. It is hard for me to even imagine that I will ever have another car as great as Betty. I almost cried when I handed over the keys. Thursday, December 18, 2008 ## My Last Day at Bell Labs After 11 years working at Bell Labs, today was my last day. For the last 9 of these years I have been the head of a department that has done research on topics ranging from neuroscience to theoretical physics to experiments on quantum computing. During that time I have had some truly exceptional scientists in my department. I wish I could say that I helped them all with their research, but that is far from true. Someone once described my job as being like the sport of curling -- sweeping the ice so that the stone can go in the right direction. The scientists in my department knew better than anyone else what direction they should be going. What they needed from me most, was just removal of various impediments, and good strong representation to the higher authorities. I like to think that I managed to provide this on most occasions. In trying to write an homage to Bell, I could think of nothing better than simply the names of the people who have reported to me, and where they are now. • Loren Pfeiffer, Ken West, and Kirk Baldwin will be leaving Bell for Princeton in Spring of 2009 • Mike Manfra is a Professor of Physics, Material Sciences and Electrical Engineering at Purdue • Bob Willett remains at Bell • Sharad Ramanathan is a Professor of Molecular and Cellular Biology at Harvard University • Ronen Rapaport is Professor of Physics at Hebrew University • Gang Chen remains at Bell • Nicolai Zhitenev is a researcher at the National Institute for Science and Technology • Girsh Blumberg is a Professor of Physics at Rutgers University • Oleg Mitrofanov is a researcher at London Center for Nanotechnology • Chris Fuchs is a researcher at the Perimeter Institute • Anirvan Sengupta is a Professor of Physics and Biology at Rutgers • Boris Shraiman is Permanent Member of Kavli Institute for Theoretical Physics at Santa Barbara • Michale Fee is a Professor of Neuroscience at MIT • Mark Schnitzer is a Professor of Biological Sciences and Applied Physics at Stanford • Rafi de Picciotto founded a startup company in Isreal • Stephen Van Enk is a professor of Physics at University of Oregon • Chandra Varma is a professor of Physics at UC Riverside • Phil Platzman is a researcher emeritus at Bell • Anton Andreev is a professor of Physics at University of Washington • Partha Mitra is a researcher at Cold Spring Harbor I'm sure I missed some, as I'm reconstructing this list from memory. I'd like to thank all of these above listed people for their support, their friendship, and their great research that made me look good just by being associated with them. In addition to these members of technical staff there were quite a few excellent post-docs (and it is more likely that I've missed a few here) • Alex Punnoose is a professor of Physics at City College of New York • David Lubensky is a professor of Physics at University of Michigan • Joel Moore is a professor of Physics at UC Berkeley • Aris Moustakas is a professor of Applied Physics at University of Athens • Alexei Tkachenko is a professor of Physics at University of Michigan • Stephan Schmult is a researcher at the Max Planck institute in Stuttgart • Richard Hahnloser is a professor of neuroinformatics at ETHZ in Switzerland • Luca Marinelli is a researcher at GE • Evgenii Naramanov is a professor of Electrical Engineering at Purdue • Raissa de Souza is a professor at UC Davis • Oana Malis is a professor of EE and Physics at Purdue Similar thanks to all of these people. There were also some wonderful students (and I'm certainly certainly missing many many more here) • Simon Trebst is a researcher at Microsoft Station Q • Gunnar Moller is a postdoc at Cambridge • Anna Lopatnikova, is a hedge fund manager • Yaroslav Tserkovnyak is a Professor of Physics at UCLA • Ilya Berdnikov defended his dissertation yesterday at Rutgers and is at a financial firm • Nada Petrovic is working on her PhD at UCSB • Mara Baraban is working on her PhD at Yale Of course during my time at Bell I had some great managers too • Peter Littlewood, now head of the Cavindish Lab at Cambridge. • Don Hamann, now adjunct faculty at Rutgers. • Cherry Murray now deputy director at Livermore National Lab • Federico Capasso, now a professor at Harvard • Dave Bishop. Now CTO of LGS, • Alice White, now head of North American research for Alcatel-Lucent • Martin Zirngble, now head of physical sciences research for Alcatel-Lucent I want to thank them all for their support. Some of these people were truly exceptional managers and they all fought very hard for us in times of painful downsizing. In addition, the other department heads who I worked closely with were also an exceptional bunch. • David Tank is a professor of genomics(?) at Princeton • Pierre Wiltzius is dean of sciences at UCSB • John Rogers is at the Beckman Institute in Urbana • Eric Isaacs is now deputy director of sciences at Argonne National Lab • Dick Slusher is director of the quantum institute at Georgia Tech • Elsa Reichmanis is a professor of chemistry at Georgia Tech • Art Ramirez is a research director at LGS • Susanne Arney remains a department head at Bell Labs • YK Chen remains a department head at Bell Labs • John Gates, not sure where he is. I'd certainly like to thank them all for their help and friendship too. Some of these people were undoubtedly the people I turned to first when things got tough. Finally there are a bunch of other people who don't fit into any of the above categories because they were outside of my management chain. It was also a pleasure to have scientific (or other) discussions with (and in some cases write papers with) the following people • Doug Natelson, now a professor of Physics at Rice • Mark Ericsson, now a professor of Physics at UW Madison • Don Monroe, now a science journalist • Paul Citrin, now teaching high school in NJ • Xing Wei, not sure where he is now • Claire Gmachl, now a professor of Engineering at Princeton • Paul Kolodner, still a researcher at Bell • Joanna Aizenberg, now a professor at Harvard • Tom Marzetta, still a researcher at Bell • David Abusch-Magder is the principal of a school in Chicago • Don Tennant, now director of operations of Cornell Nanocenter • Sivarama Venkatessan, still a researcher at Bell • Gerry Foschini, still a researcher at Bell • Tony Novembre, assistant director of Princeton PRISM • Harold Hwang, professor of Materials at university of Tokyo • Gabi Ernst, works for Bosch in Stuttgart • Glen Kowach, now a professor of chemistry at City College of New York I've probably missed at least dozens more in this category. Then I could start in thanking the support staff (who is, as usual, totally unappreciated by most), the higher management, the people in completely different parts of the company, the team in Ireland, the team in the Netherlands, the team in France, the government gang, the IP team, and the list goes on and on. I apologize to those I have not listed by name here. At any rate, these people (and the many who I did not list by name) were the people at Bell who worked with me, in one way or another, over the last 11 years and made my experience at Bell truly amazing. Thank you all! Tuesday, December 16, 2008 ## Report from Station Q Meeting Several years ago Microsoft made a rather bold decision to fund a substantial research project (now known as “Station Q”) exploring one particular approach to quantum computation, known as topological quantum computation. This project funds some top-notch physicists and mathematicians who work for Microsoft, as well as funding many other researchers at universities around the country and around the world. This has been a huge shot in the arm for my part of the physics community, which had been languishing due to insufficient government funding. Despite my loathing of Windows Vista, I have sworn not to say anything bad about Microsoft because I am eternally grateful to them for making my life as a scientist a whole lot more interesting. Last week Microsoft hosted its biannual Station Q progress meeting at their research center in Santa Barbara. This is the sixth such meeting and, although the first few meetings were depressingly void of good experimental data, the last few have been extremely exciting and filled with plenty of interesting new things to think about. The experiments have been focused, to a large extent, on understanding the physics of one state of matter known as the nu=5/2 quantum Hall state. In particular, the experiments are trying to demonstrate that the state of matter is "non-Abelian" (maybe I'll blog about what this actually means some other time.. see also my upcoming web page at Oxford). At any rate, if the experiments manage to show this to be true, as all the theorists already believe, it would potentially provide a new route to building an error free (decoherence free) quantum computer -- essentially doing an end-run around the main stumbling block that has so far stymied all attempts to do real quantum information processing. Of course all of the experiments are insanely difficult. They are all done at temperatures between 10 and 50 millikelvin above absolute zero. That is something like 1/10000 of room temperature. And the actual interesting part of the experiment is just a few square microns large. This is not for the faint-of-heart. Maybe some day I will blog about all of the interesting experiments that were discussed at this meeting and how I see status of this field. However, for now I want to talk about two of the talks that were the most controversial. Both talks were research projects that I presumably have some responsibility for. One talk was given by Bob Willett, who is a researcher in my group at Bell labs, although he certainly runs his show without any help from me --- and as of thursday I am no longer at Bell anyway. The other talk was given by Woowon Kang from University of Chicago --- I worked very closely with him, proposing many pieces of the experiment. I spent much of the conference discussing the results of these two talks, and debating whether they were "right" or not. I think most people agreed that in both cases the data was certainly interesting, but in neither case could any conclusion really be drawn yet. The problem in both cases was that data was shown where it was very hard to see if there was really a signal behind some very noisy results. And in neither case was the necessary detailed statistical analysis done. As a result the feisty audience tried to hold both of their feet to the fire. (Note: part of the point of this conference is to show preliminary data, so even if their feet got burned a bit, they should not be blamed). The discussions that ensued over this data made me think very hard about how to treat murky data. One sometimes gets the idea that science is very clear -- test a hypothesis and the result is either right or wrong. But frequently the results come out inconclusive... or barely conclusive. In some cases results get accepted by the community on tenuous data and later have to be reconsidered. Of course, in the best of all worlds, data is crystal clear and there is little room for doubt. But more often this is not the case. One has to be even more careful when there is a great driving force for a community to come to a particular conclusion. In this case, the community is predisposed to want to see results that confirm what we all expect. It is likely that the answer will turn out to be what we have predicted for years -- but we should keep an open mind that it may not turn out this way and we certainly should not jump to declare victory until the data really is incontrovertible. (On the flip side, there may be others in the community predisposed to disbelieve the data, and they should similarly agree to keep an open mind). With this in mind, I decided it was a good idea to go back and reread the words of the great physicist Richard Feynman: "Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself—and you are the easiest person to fool. So you have to be very careful about that. After you've not fooled yourself, it's easy not to fool other scientists." I personally hope that at least one of these works (or perhaps another similar experiment from another group) turns out to be correct, as this will give further life to a very exciting scientific field. But also, I hope that, despite all of our desire to see these experiments prove the theories, the community lives up to its scientific responsibility to accept the data as correct only when it really has been established, and to raise appropriate questions until that time. Thursday, December 11, 2008 ## Everyone should know who Marie Curie and John Bardeen are Needless to say, there are many scientists out there who left important marks on our world. Even the least educated amongst us usually know something about Einstein “that genius guy with the crazy hair.” But Einstein perhaps is unique among scientists in how widely recognized he is. I would guess that even such greats as Darwin or Newton are nowhere near as universally known. Who else does every school child know about, and who should they know about? In the current state of affairs, I think the general public is woefully ignorant of the sciences (as well as being almost completely innumerate). The question I would like to pose is, given that we scientists cannot reasonably demand that the public knows about every important scientist, we might want to come to a consensus as to which scientists should be in the educational canon. Marie Curie: When I was growing up, one scientist that I really admired was Marie Curie. Most of the educated, have probable heard of her, I would hope. Her story is truly a great one. Coming from a relatively poor background in Poland, she eventually ended up winning two Nobel prizes (A prize in Physics in 1903 with her husband Pierre and Henri Becquerel for discovery of radioactivity and a solo prize in Chemistry in 1911 for isolation of Radium). She achieved all this despite being one of very very few women in all of science at the time. Perhaps the atmosphere in science was so difficult for women that you really had to be this good to have anyone pay attention to you at all. Incidentally, in 1943, when biographical movies were very popular, a movie was made about Curie starring Greer Garson, who was nominated for an academy award in this role. Although clearly Hollywood-ized at least a bit, it is still very much worth the rental. There are also several good books about Curie. I remember reading a children’s book about her when I was about nine years old and being completely enthralled – in particular by one episode where she was so engrossed in her work that she only ate radishes and cherries for several days then fainted from exhaustion. For anyone who doesn't know Curie’s story in detail, go rent the movie or read a book about her. So let us set our bar about this high. In order to be in the required educational canon, you must be arguably as important as Curie. There have been several hundred Nobel laureates since the inception of the prize in 1901, but a mere handful of people have gotten two. Even Einstein only won a single prize, although many insist that he was entitled to one more for general relativity, which was not really convincingly confirmed until after his death. So who else is on the list of double Nobel winners? Linus Pauling: His first prize was in Chemistry in 1954 for the orbital hybridization model of chemistry. Most high school students who study chemistry do learn this, at least vaguely (Remember sp3 and sp2 hybrids?). After this, as a prominent scientist, he became an outspoken opponent of Nuclear armaments, and he ended up winning the Peace prize in 1963 during the height of the cold war, for campaigning against nuclear testing. But the Peace prize is a strange one – it is usually a prize of the time, as this one clearly was, and is meant to effect the progress of diplomacy and peace in the world. Although Pauling was a great man in multiple ways (and the only person to have ever won two solo Nobel prizes) it is also true that he did not win two science Nobels. John Bardeen: I can already hear people scratching their heads and saying “Who?”. Yeah, that’s my point. Bardeen should be a name we all know – he won two prizes in physics for two of the most important advances of the last century. His first prize was in 1962 for the invention of the transistor along with Walter Brattain and William Shockley (the work was done at Bell Labs in the building where I’ve worked for the last 11 years and will work for one more week before I go off to Oxford). It is hard to overstate how important this advance has been to the world, as it was the fundamental advance that allowed the computer age and the information age to come about. The laptop I am using right now contains over a billion transistors inside of it. In fact, practically no electronic device these days is without them – hundreds, thousands, millions, or billions of them. Yes, it is true that the transistor was only the first step in the electronics revolution, but it was a very important step. (Perhaps as important was the integrated circuit that allowed many transistors to be made at one time – Kilby won a Nobel in 2000 for this advance). Bardeen’s second prize was in 1972 for creating the theory of superconductivity, along with Leon Cooper and Robert Schrieffer. The fact that at low temperature certain materials lose all resistance to electricity was discovered in 1911 by H. Kamerlingh Onnes (he won the Physics Nobel in 1913). If you make a loop of sufficiently thick superconducting wire and you start running current around the loop, it will literally continue flowing for the age of the universe without any noticeable reduction in current (as long as the temperature stays low). It took half a century of work to come up with a theory of why this happens And when the theory was finally worked out it was incredibly beautiful – universally hailed as one of the major intellectual milestones of the century. Indeed, the theory even gave us hints at the structure of symmetry breaking for fundamental particles and the electro-weak interaction (the so-called Anderson-Higgs mechanism). Considering this remarkable two-fer, it is amazing that so few have heard of Bardeen and that his is not a household name like Watson and Crick, or Feynman – who admittedly had some very large publicity operations on their side, but only had one Nobel each. Fredrick Sanger: OK, here I admit that I am a bit guilty of what I blame the “ignorant masses” for – saying “Who?”. Clearly my education in chemistry is lacking. Once again, we have a double Nobel Laureate and no one has ever heard of him. Well, to be more honest, I did vaguely know who he was, but I couldn’t actually remember what his prizes were for and I had to look them up. His first prize, in Chemistry in 1958 was for determining the structure of insulin. This was the first protein to be sequenced (it took 12 years for him to do so) and this result started the trend of examining the relation between structure and function of biological materials. His second prize, shared with two others, also in Chemistry, in 1980, was for developing techniques to figure out the sequences of long DNA and RNA molecules – also incredibly important in modern biology and biochemistry. And that is all she wrote. Only four people have ever been double Nobel laureates. Isn’t it odd that every high school student (much less every student potentially interested in science) isn’t reading their biographies? Maybe they should be. How about a remake of the Curie movie starring some beautiful starlet like Anne Hathaway or similar? The supposedly politically conscious Hollywood might be interested in promoting better images of women than most of what I see in movies these days. Come on Hollywood, I dare you. Wednesday, December 10, 2008 ## Physics for cocktail parties, or for five year olds. For physicists, one of the most difficult, even treacherous, situations is the cocktail party. I do not say this because I think physicists lack conversational skills. That is a very ill-deserved stereotype: most physicists are actually quite personable and frequently very funny. Yes, perhaps some physicists are a bit unusual, perhaps some are not very fashionably dressed, and perhaps some lack Emily Post manners (these quirks are frequently to the dismay of their spouses or significant others). No, I say that cocktail parties are difficult because invariably someone asks “what do you do for a living” which puts the physicist in a difficult position. On the one hand, most physicists would love to start an hour long lecture on their chosen topic of devotion. Virtually every physicist absolutely loves their work, or they would not have chosen the rather difficult road to being a physicist. But the unsuspecting cocktail party guest does not really expect, and rarely wants, to hear an hour long lecture on the beauty of spontaneous symmetry breaking, the renormalization group, or the like. And nothing is more painful to the physicist than trying to reduce some mind-blowing concept to a single one sentence answer. Wouldn’t James Joyce cringe to be forced to summarize his Ulysses to one sentence, perhaps as “the story of a guy having a day that feels pretty long.”? But nor would you want Joyce to give you the whole story over a gin and tonic. I have still not come up with a perfect strategy for handling this type of situation. Usually I resist giving more than one word answers until I am convinced that the person who asked the question really wants to hear the extended remix for the answer, in which case, once pushed, I can talk incessantly. I remember once launching into an hour-long rant about what a travesty it is that the common educated person does not know who the physicist John Bardeen is, the same way that people know who Watson and Crick are (for those of you who don’t know, maybe I’ll write a blog entry about Bardeen soon). Another time I raged about why nonpertubative physics is the fundamental problem that all theoretical physicists need to wrestle with for the next century. I’m not sure how well these, or any other of my spontaneous cocktail party lectures, were received, but I think that having an audience who had already had a few cocktails might have helped. The reason this all comes to mind is because of what transpired over my Thanksgiving holiday last month. As in previous years, I went up to Rochester NY to visit my family. During the traditional Thanksgiving feast, we each tried to explain to the youngsters at the table – my niece Seneca (almost 4.5 years old) and my nephew Milo (2.3 years old) – what we did for a living. Well, trying to explain to a five year old what a physicist does is a tough task, and as usual I tried to squirm out of it. But rightly pushed by their mom (“you have to give them a good answer so they can grow up to be scientists too”, which, incidentally, I would very much like to see) I struggled to come up with something short and sweet and simple. My quick answer was “A physicist is someone who tries to figure out why things work the way they do… like why something falls when you drop it” But I was not completely happy with this as an answer. On the other hand, even after some thinking, I still have yet to come up with a better response. If any of the physicists (or non-physicists) out there want to give a shot at one sentence that summarizes what a physicist does, suitable for five year olds and perhaps cocktail parties, please post in the comments section or email it to me directly. With luck at next Thanksgiving I will be able to start the process of turning my niece and nephew into future physicists (although perhaps they might want to focus on kindergarten first). Tuesday, December 2, 2008 ## Freshman Physics During my first two semesters at Oxford I'll be relieved of lecturing responsibilities. Nonetheless, I still have to do two-on-one tutorial sessions to the tune of about 6 hours per week. I agreed to take over the tutorial responsibilities of my friend Roderich Moessner who left Oxford last year, thus vacating the job that I landed in. This included tutorials for an advanced third year undergraduate physics course called "Condensed Matter" a second year course on Statistical Physics, and a first year course on electricity and magnetism. Since I have to tutor these subjects I thought it might be a good idea if I were to go through the curriculum and remind myself what undergraduate physics is all about. Perhaps predictably, I found the two advanced courses to be a breeze, but the first year course was really hard! Maybe I never learned E+M correctly the first time through, or maybe the professor is just being difficult and assigning hard problems for homework. At any rate it looks like I have some reviewing to do in the next few weeks. Anyone out there have a good book on waveguides and transmission lines? Wednesday, November 26, 2008 ## Getting ready to move I have an rather imposingly long list of things I need to do before I move to England. One by one they are being checked off, but still I think there is going to be a whole lot of last minute scrambling. Visa Woes My friends from other countries, particularly those without green cards, are always bemoaning the complications of getting their visa in order. Now I know what they feel like. The UK is cracking down a bit on immigration and as a result the process for getting a work visa has become pretty darn complicated -- including various types of biometric scans. Starting this month it is even more complicated as they are instituting some sort of foreigner id card Nonetheless, I did manage to get my work visa... but the process makes me feel like i had best stay out of trouble once I get there lest it gets revoked and I have to go through the process all over (maybe that is the point). Medical Being that I have no idea what the British health care system is like I've decided to go get a whole lot of tests done here while I still have good old american expensive insurance. So last week I went to the doctor, got a couple of vaccinations, had some tests done and the doctor reported that I'm in fine shape (apparently he didn't see me sucking wind while trying to get back into running this summer). Fortunately, my cholesterol is extremely low, so I can go to the UK and eat all the artery-clogging food with reckless abandon. The visits to the dentist were a bit less perfect. I've got to have a few minor things done in the next month which, no doubt, will be exceedingly unpleasant. My Apartment Before the economic meltdown I thought that I might be able to sell my apartment in Hoboken for a nice penny. That was then, this is now. So I'm going to try to rent it for a while. But before that happens there are a whole lot of things in the apartment that need to be fixed. The windows leak like a sieve and need to be replaced. The shower leaks on the poor guy downstairs and needs to be patched. The hot water heater works only sporadically. And much of the apartment needs to be repainted after the apartment above me flooded on me. All this needs to be done in the next four weeks. ... and of course I need to rent the thing. Wish me luck. Finding an Apartment Real estate in Oxford is like real estate in NY or the bay area -- insanely expensive unless you like living in a shoebox. Fortunately, Oxford owns some properties that it is willing to rent to its faculty for reasonable rates. The place I will be staying (on Canal Street in the Jericho neighborhood of Oxford) is fine as far as having enough floor space. And it is very convenient to the Theoretical Physics department (on Keble Road) and to Somerville College (on Woodstock Road). Unfortunately, the plan for building this apartment appears to have been to keep adding walls until they had twice as many rooms as you need, each with half the space that you would like. Not sure what I am going to do with all the small rooms. I guess one advantage of having extra rooms is that there will be space for friends to come visit me (hint hint). Moving Oxford uses only one moving company, and they have been a bit reticent about giving me all the details -- like cost breakdown, and how long the move is going to take. I gather however that when it comes to moving they are efficient like locusts... they enter the apartment and an hour later the apartment is completely empty. I'm not sure they are playing with a completely full deck though. Oxford graciously agreed to pay moving costs up to 6,000 GBP. (These days 1.5$ =1 GBP) . The estimate for moving costs was 5,945 GBP. Coincidence? Perhaps.

Cleaning out the junk

Before the movers arrive I'd really like to get some of the junk out of my apartment. I've managed to take a bunch of boxes of stuff up to my parents home in Rochester (things they claimed to have use for -- except maybe the toaster. Not sure why that was included). Then another bunch of stuff was taken to the Salvation Army for donation. About a hundred pounds of books went to the nice people at the local used book store. Some random stuff of dubious value will go to friends who speak up at the right moment. Anyone want a nice desk lamp?

Betty

Perhaps the only possession to which I am emotionally attached these days is Betty, my 1997 Honda Civic. 170,000 miles and never had any substantial problems. I'm really going to miss her. I'm hoping a friend will buy her so I can get visitation rights.

Wednesday, November 5, 2008

## I'm so proud of my country

I have not blogged for almost a month now. I've been pretty crazy trying to get ready for my big move, but also working on the Obama campaign, pounding the pavement of urban Allentown PA to get out the vote. The once proud factory town is pretty poor now, with many houses foreclosed and empty. People looked at me and immediately knew that I didn't belong in the neighborhood. But once they saw that I was an Obama volunteer, they treated me like a long lost brother. Many of them told me how excited they were about electing Obama, not only because he is black, but because they are simply tired of a government that has completely ignored their frequently desperate and now worsening problems. One woman told me that her mother had been very sick, but she kept saying that she wanted to live long enough to vote for Obama. Unfortunately, she died last week but she was buried with her Barak Obama pin.

The election of Obama has really made me feel very proud of my country. Growing up, I would never have believed that in my lifetime a black man would be president. Even as recently as last year, I had great concern that most of this country is simply too biased to give Obama a fair hearing. I'm happy to find out that I was wrong. It is really an amazing moment in history.

Of course, now that Obama has been elected, he has his work cut out for him. My country is in such a deep hole that it isn't clear to me that even Obama, and the first rate team that I'm sure he will assemble, will be able to make a whole lot of progress climbing out of it. I do have confidence, however, that Obama will be wise enough to not keep digging.
Monday, October 6, 2008

## Nobel Bets

Every year I try to guess who will get the Physics Nobel prize (No I am not a candidate). My bet this year is for the discovery of neutrino mass by super-K in japan in 1998. It has been ten years and since that time the discovery has been verified by other groups and by other methods. Here is a nice description of the experiment. I'm not sure, however, who the award should be presented to -- it is a huge collaboration. Doug Natelson at nanoscale views is betting on Aharonov and Berry -- which is one I've suggested several times before also.

Within a few days we'll find out.

UPDATE: The prize went to Nambu, Kobayashi, and Maskawa. Not a combination I would have guessed (obviously a combination lobbied for by Japan). This might kill the chances for Higgs and Goldstone.

A rather interesting prize was given in chemistry for green flourescent protein, clearly very important for biochemistry (although some have argued the prize should have been in biology not chemistry). Here's an amazing story about a guy who was really crucial in this development who should get many more kudos for his contributions. And if anyone is in alabama they should buy him a drink or two.
Tuesday, September 30, 2008

## Geeking out

(1) If you run OSX and you happen to use the free version of yahoo mail you have probably noticed that there is no automated program that alerts you when you have mail. After suffering this indignity for years, I have finally done something about it. You can find instructions for making this program work for you here. Took me about two hours to write, and another hour to write the how-to. I know it isn't elegant, but it works very nicely.

(2) And more on the geek front. Since I am returning my nice laptop to Bell when I quit, I just ordered a new tablet to be my future work machine. The Lenovo x200t. Pretty sweet machine! I wimped out when I saw the price go way over 3,000\$ and I decided I didn't really need the solid state drive for another 800 bucks.

(3) Final geek goodness: My friend veronique christensen has been working on a new website called obsessable.com dedicated to geek equipment. Yay for geeks!

Update (1) Yeah, I know, it sometimes doesn't work. I know what is wrong and I need to tweak it for reliability. Maybe when i have a few free hours.

Update (2) The x200t is pretty sweet. Size is always the compromise. Either it is too small to give good screen real-estate, or it is too big to carry really easily. I think the x200t is probably just a hair too big, but not bad. The handwriting recognition is extremely good and I hope to use this to take all my notes, do calculations etc. The one thing that is disappointing is vista 64 bit. Way too many things install incorrectly or not at all. I spent almost two days trying to get MikTex installed. All the geeks out there, I'm sure already know how important this program is. (Yes, i finally succeeded, but only after a whole lot of grief).
Sunday, September 21, 2008

## Preparations 101

I'm told the British don't use the phrase "101" to describe an introductory course.

What I need right now is a 101 course (or whatever you want to call it) on moving to the UK. For those of you who don't already know, I've accepted a job as a Physics Prof at Oxford. But the preparations for getting myself, and my little world, across the pond are mind-boggling. And you all thought that physics was hard.

Among the things I need to do: Move my stuff, Set up new apartment, Get a new bank account, Retire from my current job, Roll over my 401K, Get a work permit for the UK, Get a physical before leaving, Get vaccinations, Sell Betty (my honda civic), Buy a new laptop (mine belongs to work), Sell my NJ apartment (which means fixing everything that is broken first)... and all of this is before I even know what (if anything) I am supposed to be teaching first semester of 2009. (Actually I think I don't have to teach my first semester.) But the whole thing seems more complicated than invading Normandy... so to speak.

And yes, being a Prof at Oxford means I get to wear the big black gown at dinner (Think Hogwarts) But no, I don't wear it while teaching.

Oh, and by the way, for those of you who might be interested, tomorrow I give the Physics department colloquium at Columbia University.
Friday, August 29, 2008

## Why Complex Matters?

Why did I choose the title "Complex Matters" for my blog? You might think that I am writing about complex matters in life. Life is indeed complex and the matters in life that are the most important are certainly the most complex. But this is not the reason. No, the reason is far more nerdy than that. The title of my blog is really a reference to states of matter that are complex --- what I study for a living. Among other things, I study the science of matter ("stuff") made up of many particles -- say electrons -- where the laws that govern the individual particle may be simple, but the behavior of the collection of particles is complex. Sometimes this is called "emergent phenomena". In fact, in much of modern science it is exactly this type of complexity that really matters.
Thursday, August 28, 2008

## Warming up

In a little while I intend to start a real blog. Before the start gun fires I thought it might be a good idea to do a little warm-up blogging. Since this is a blog about physics (among other things) I had better make sure I can write equations like  8 \pi T_{\mu \nu} = G_{\mu \nu} . OK, I admit, it doesn't look great, but it will do.


text:
What is the rate of increase in solubility in grams per degree (in other words, for every degree of temp. According to your data, how is solubility of KNO 3 affected by an increase in temperature of the solvent? 3. 8g of KNO3 and 1. Which of these salts decreases in solubility as the temperature increases. Butane is virtually insoluble in water and has a solubility of 61 milligrams per liter at 20 degrees Celsius. What mass of KNO3 will crystallize out of the solution if exactly 100g of its saturated solution at 75C is cooled to 25C? Is there anyone that can provide a template to work from in order to solve this problem? Thanks. Created Date: 4/29/2015 4:37:19 PM. -Heat in hot water bath until dissolved- you may stir. The solubility of a substance is usually given in g/100cm 3. The solubility of CuSO4 is 60g/100g water at 50 degrees and 20g/100g water at 0 degrees. The solubility graph is a very useful tool because it tells you the amount of potassium nitrate that can be dissolved per "100 mL" of water in order to have a saturated solution of potassium nitrate at a given temperature. enthalPy of solution of eleCtrolytes This table gives the molar enthalpy (heat) of solution at infinite dilution for some common uni-univalent electrolytes. 0 Degrees Celsius 40. 3 kPa (760 torr) is 1. What mass of a solid of precipitate is formed out of the. go straight across. Write the equation and the equilibrium. The solubility constant, K sp, has a fixed value at a given temperature and is independent of the concentration of the individual ions. Purpose: Find crystallization temperatures for 7 concentrations of KNO3 and make a solubility graph. Which of the salts shown on the graph has the greatest increase in solubility as the temperature increases from 30 degrees. An increase in atmospheric pressure causes an increase in the solubility of KCl. The solubility of KNO3 is 155 g per 100 g of water at 75 degrees celcius and 38. Which Salt Could This Be And Why? Solubility At 20 Degrees Celsius In 100 G Of Water: KCl Is 10 G And KNO3 Is 30g The Answer Is Supposed To Be KNO3, But How Did They Get That?. Also known as potassium peroxydisulfate or KPS, it is a white solid that is highly soluble in water. 50555555555556. Construct a solubility curve using the mass of solute that will dissolve in 100 g of water at a specified temperature. Increasing the temperature of a KNO3 solution from 30 degrees Celsius to 60 degrees Celsius decreases the solubility of KNO3 by half. 8 ml water @ 25 C. The saturation temperature would then be higher. For very soluble substances (like sodium nitrate, NaNO 3), this value can be quite high, exceeding 10. Here's what i have worked out: I made a graph which indicated that at 70(degrees)C there were 125g of Potassium Nitrate and at 20(degrees)C there was 30g. 6×10 –26: Mercury(II) iodide: HgI 2: 2. What is the total number of grams of potassium chloride needed to saturate exactly 300 grams of water at 10°C? 1)40 2)45 3)80 4)95 20. When 50 grams of potassium chloride, KCl, is dissolved in 100 grams of water at 50 ºC, the solution can be correctly described as: Which of these salts decreases in solubility as the temperature increases. 1 80 38 90 38. ! 154!! “Easily,”Isay,“whenyoustartwithahotsolutionandletitcool. 69 g/100 ml is the solubility of NaCl at 50 o C. Then, draw a horizontal line to the solubility axis. the molarity and molality are also similar in magnitude: (0. These data were determined empirically by physical experimentation. SOLUBILITY: ammonia liquid [NH 3]: 10,52 (0°), 10,4 (25°) water [H 2 O]: 13,1 (0°), 21,2 (10°), 31,6 (20°), 37,9 (25°), 46 (30°), 63,9 (40°), 110,1 (60°), 168,8 (80°), 243,6 (100°), 786 (200°) hydrazine [N 2 H 4]: 14 (20°) glycerol [HOCH 2 CH(OH)CH 2 OH]: soluble diethyl ether [C 2 H 5 OC 2 H 5]: solventless trichloroethylene [CHClCCl 2]: 0,01 (15°) ethanol [C 2 H 5 OH. Barium molybdate. Thus, the solubility of KNO₃ at 50 °C is 90 g/100 g water. why-is-pbi2-not-soluble-5194540 5 / 5 based on 2 votes. ethanol) ›. Lead(II) nitrate's molar mass is 331. Solubility rules Kohath berry, james clark , justin. How much KNO3 solute is saturated at 40 degrees? Solubility curves 2 DRAFT. (2) The solubility of NH3 decreases, and the solubility of KCl increases. 40 kg/L of water at 100 ºC. Relative Humidity-Temperature Relationships of Some Saturated Salt Solutions in the Temperature Range 0 0 to 50 0 C 1 Arnold Wexler and Saburo Hasegawa. I was actually trying to find data on dextrin solubility in alcohol solution, but that has been more difficult to find. 3% of the original SO 2 Cl 2 (by moles) has decomposed to reach equilibrium. The K sp of NaCl is quite large, poking around the internet I get the value of 37. 10) The solubility of the solution would be lower because the temperature was too low. Solubility of pure gases like. A solid mixture consists of 27. Example: Estimate the solubility of Ag 2 CrO 4 in pure water if the solubility product constant for silver chromate is 1. If you stir 20 grams of KNO3 in 100 mL of water that is at 50 degrees Celsius, will all of it dissolve? Yes 3. 9 grams per 100 ml, and the solubility of KH2PO4 is 23 grams per 100 ml. Part A Preparing a Saturated Borax Solution. The solubility of micro ferts varies from chelate to chelate, and unfortunately there is little information about the solubility of Plantex CSM+B. asked by Lauren on October 6, 2014. (b) Write the expression for the solubility product constant, Ksp, and calculate its value. 60 g of KNO 3 in 100 g of water at 70°C c. 300 Based on Table G, determine the total mass of NH3 that must be dissolved in 200. Kno3 Dissolved In Water. In order to find the solubility of the salt at 60^@"C", start. The solubility of potassium nitrate is 38g/ 100g H2O at 20degrees C and 1. Solubility At 20 Degrees Celsius In 100 G Of Water: KCl Is 10 G And KNO3 Is 30g The Answer Is Supposed To Be KNO3, But How Did They Get That? This problem has been solved! See the answer. Calculate the value of K p for this system. 50 X 10^2g/ 100g H2O at 70 degrees C. asked by Emily on March 20, 2011. This solution is supersaturated. 60g of solid KNO3 should form. 8388879824) will be used to calculate the equilibrium concentration for all species. go straight across 7. SOLUBILITY RULES. A mixture contains 13. Nitrate Of Potash White Potassium Nitrate Powder KNO3 For Dry Place Storage. Name, Date, Hr/Per_____ KEY _____ Solubility Curves SOLUBILITY GRAPH A Answer the following questions based on Solubility graph A 1. Based on Reference Table G, when 100 grams of water saturated with KNO3 at 70°C is cooled to 25°C,. Temperature (∘C) Solubility (g/100 g H2O) 20 11. the solubility of lead(II) nitrate and potassium nitrate is the same at about 50°C (approximately 80 g per 100 g water, where the solubility curves of these substances cross). At what temperature does KI have a solubility of 150 g/ 100 mL water? ~25 ºC 7. The substances are listed in alphabetical order. What happens during cooling?. From this graph you can know the solubility at any temperature between 0degree and 100 degree C. Thus, the solubility of KNO₃ at 50 °C is 90 g/100 g water. , Ce2(SO4)3: When 30 grams of potassium nitrate, KNO3, is dissolved in 100 grams of water at 20 ºC, the solution can be correctly described as:, saturated: A solution of potassium chlorate, KClO3, has 20 grams of the salt dissolved in 100 grams of water at 70 ºC. Insoluble in diethyl ether. Solute entropy favours solvation, this reflects the higher solubility of flexible molecules, this is because in the solid they are all locked up, while in solution their rotational and vibrational modes are populated. Calculate (a) the molality of glycerol, (b) the mole fraction of glycerol, (c) the molarity of glycerol in the solution. Higher temperatures = greater energy. The saturation temperature would then be higher. The solution is-unsaturated-saturated-supersaturated-supercritical. (a) At 10°C, 8. the solubility of two substances. I have linked an image of one below. mL of water. A precipitate is an insoluble solid formed by the reaction of two or more solutions of soluble compounds. 53 grams per cubic centimeter. This can be calculated from thermodynamics, given two constants - the enthalpy of dissolution and the entropy of dissolution. If I add 125. Temperature (∘C) Solubility (g/100 g H2O) 20 11. Which curve best represents the solubility of a gas in water? 1)A 2)B 3)C 4)D 1)60 2)70 3)80 4)90 19. __200 g sugar/100 g water_____ b. 0 mL of water and heated to 80° C. 2g of KNO3 (potassium nitrate) and 4. Consider the reaction 2C3H6 + 9O2 6CO2 + 6H2O. I´ll warm the solution up to 75degree celsius and I´ve to determine at which temperature precipitate will form. The liquid is called the solvent. To me the question does not make sense. Gases~ as temperature increases, the degree of solubility decreases As pressure increases, the degree of solubility. The idea being if using an alcohol. It appears to hit the axis at about 90 g/100 g water. Using your printed graph, tell if each of these solutions would be saturated or unsaturated: a. C is cooled to 10 degrees C. The solubility of potassium nitrate is 38g/ 100g H2O at 20degrees C and 1. For each substance, look up the temperature at 60°C and give the amount of solubility in grams that would make the solution SATURATED: 1) sodium chloride (NaCl): ~38 grams. 94g of CuSO4. 110g at 40 degrees C D. saturated c. Which of the following has a solubility that decreases as temperature increases?. 0 Degrees Celsius. 0 g of potassium chlorate is added to 60 mL of water. 10) The solubility of the solution would be lower because the temperature was too low. K sp = [Ag +] 2 [S 2-] We then substituted the relationship between the concentrations of these ions and the solubility of the salt into this equation. 140 g of KNO 3 in 200 g of water at 60°C 4. Solubility of Silver Nitrate in Water Temperature Grams Silver Nitrate dissolved per liter Grams Silver Ions dissolved per liter 0°C ( 32°F) 1220 g Silver Nitrate 774 g Silver Ions 10°C ( 50°F) 1700 g Silver Nitrate 1,079 g Silver Ions 20°C ( 68°F) 2220 g Silver Nitrate 1,409 g Silver Ions 25°C ( 77°F) […]. It shows that the solubility is 34. What mass of a solid of precipitate is formed out of the. The mixture is added to 130. 60g of KNO3 in 100g of water at 70°C c. The x-axis shows values from 0 to 90. The solubility of potassium nitrate is 38 g/100 g H2O at 20 degrees celsius & 1. does all the potassium nitrate remain in. If all the solute could be dissolved in 100 grams of water at the stated temperature, would the resulting solution be unsaturated, saturated, or supersaturated? 1) 60g KCl at 70°C supersaturated [above line] 2) 90g KNO 3. Barium fluoride. The K sp of NaCl is quite large, poking around the internet I get the value of 37. The solubility curve below is just for sugar and sodium chloride. It is approximately nine orders of magnitude less than its solubility in pure water, as we would expect based on Le Châtelier's principle. __200 g sugar/100 g water_____ b. 1 80 38 90 38. The solubility of sodium chloride is the square root of the solubility constant, K sp. Created Date: 4/29/2015 4:37:19 PM. It discusses saturated. > KNO3(aq)→K+(aq)+NO−3(aq) Now, the solubility of potassium nitrate depends on the temper. Which substance is most soluble at 60 ºC? NaNO 3 4. How many grams of NaNO3 can be dissolved at 25 degrees C? NH4Cl. Which solid has a solubility that changes least with temperature? 4. supersaturated d. Cadmium carbonate. Then, draw a horizontal line to the solubility axis. The solubility of sodium chloride in water is $$36. 60g of solid KNO3 should form. 8 g KNO3 at 20°C) = 37. The basic method is to measure the 100 mL of pure water as accurately as you can. 00 As (s alpha‐gray) 0. Otero,, Enrique Camesella, and, Antonio Correa. ethanol) ›. Industrial & Engineering Chemistry Research 2002, 41 (20) , 5109-5113. 94g of CuSO4. 110 grams at 60 °C. This process is close to or at equilibrium at 25°C. Weight of solvent alone = (b - c) g. You could contrast the KNO3 curve with the NaNO3 curve, which is nearly flat, and demonstrate how sodium nitrate dug from guano deposits is converted to KNO3. 2 g in 100 mL. So I have a solution of KNO3 (690g in 1. We are asked to solve the temperature do Potassium Nitrate KNO3 and Sodium Chloride NaCl has the same molar solubility. Reading from left to right, would this curve would _____ a. A saturated solution (23% w/v) freezes at -20. In a 100-mL beaker, prepare a saturated solution of borax by adding roughly 20 g of borax to 80 mL of distilled water. what kind of solution is 50g of NH3 at 20 degrees C? Supersaturated. The solubility of a substance is usually given in g/100cm 3. 0 g at 25°C. The solubility of KNO3 is 155g per 100g of water at 75C and 38. Materials: KNO3, test tube, stir rod, weigh boats, hot plates, thermometer, 10 mL graduated cylinder. SOLUBILITY: ammonia liquid [NH 3]: 10,52 (0°), 10,4 (25°) water [H 2 O]: 13,1 (0°), 21,2 (10°), 31,6 (20°), 37,9 (25°), 46 (30°), 63,9 (40°), 110,1 (60°), 168,8 (80°), 243,6 (100°), 786 (200°) hydrazine [N 2 H 4]: 14 (20°) glycerol [HOCH 2 CH(OH)CH 2 OH]: soluble diethyl ether [C 2 H 5 OC 2 H 5]: solventless trichloroethylene [CHClCCl 2]: 0,01 (15°) ethanol [C 2 H 5 OH. A solution is prepared by mixing 45 g of KNO3 in 35 g H2O at 70 degrees Celsius. Its solubility at 50 'C is 0. 446 (a) Complete the entries in the table. If the solution is taken to the temperature at 20°c then what quantity of Pb(NO3)2 will come out from the solution if the solubility of Pb(NO3)2 in water at 20°c is 54. Which substance's solubility changes the most from 0 ºC to 100 ºC? KNO 3 5. (c) antifreeze (ethylene glycol and water) 2. Increased temperature usually increases the solubility of solids in liquids. 69 g/100 ml is the solubility of NaCl at 50 o C. Full text of "Calculations Of Analytical Chemistry" See other formats. Instead I turned my attention toward nitrate solulubility in alcohol solution. LOGIN JOIN. A solution that conatains 120 grams of MgSO4 in 100 mL of water at 80 degrees Celsius would be saturated, unsaturated, or. Answers: 1) KClO3, 2) KNO3, 3) NaCl 4) 14 g, 5) 72 ( 2oC, 6) KNO3 and KCl, 7) 210 g, 8) 55 ( 2g,. At 10 ˚C, the solubility of KNO3 is 30 g/100 g H2O. Therefore, solubility is the dependent variable and as such is placed on the vertical or y-axis of the graph. in solubility in grams per degree (in other words, for every degree of temp. Is there more KNO3 or NaCl dissolved at 5 ° C? 2. 80g at 20 degrees C. Units of solubility are given in grams per 100 millilitres of water (g/100 ml), unless shown otherwise. Which of these salts decreases in solubility as the temperature increases. From there, draw a vertical line until it meets the solubility curve of KNO₃. , Ce2(SO4)3: When 30 grams of potassium nitrate, KNO3, is dissolved in 100 grams of water at 20 ºC, the solution can be correctly described as:, saturated: A solution of potassium chlorate, KClO3, has 20 grams of the salt dissolved in 100 grams of water at 70 ºC. 4 g will dissolve in 20 g of water at 340C 3. Write the equation and the equilibrium. Fus  CHEM1220 !!]!!!!!]!!!!!]!!!). grams of water to produce a saturated solution at 20. 2019 05:40. 60g at 10 degrees C C. slope downward c. Thus the solubility of most solids in water increases with increasing temperature. NH 3 at 20 ºC d. Enter an initial concentration for the ionic compound. KNO3 solubility in alcohol solutions - posted in Pyrotechnics: The talk of using alcohol solutions or alcohol to wet compositions and BP has got me thinking. 43 x 10-3 gram per liter at 25 °C. Use the CRC handbook or other valid reference to look up the solubilities for potassium nitrate, KNO3, at 100 C and 0 C. What are the dissolved particles in a solution containing a molecular solute? What is the name for this kind of solution. Please Login To View The Answer. A mixture contains 13. Answer the following questions relating to the solubility of the chlorides of silver and lead. Table 2 presents a summary of solubility values in different units for NaCl in water at 15 ºC. Cool the mixture to 50oC so that the KNO3 will precipitate and the KClO3 will stay in solution. In terms of saturation, what kind of solution is 110g of KNO3 at 60 degrees C? 90g. You could contrast the KNO3 curve with the NaNO3 curve, which is nearly flat, and demonstrate how sodium nitrate dug from guano deposits is converted to KNO3. If I add 125. The y-axis shows values from 3. The x-axis shows values from 0 to 90. K c = [M y+] x [A x-] y. All four substances have higher solubility at higher temperatures in the range from 0 to 100 degrees Celsius. Lead(II) nitrate's molar mass is 331. 1021/ie020260k. (a) At 10°C, 8. But KNO3 on the skin will not be a problem if washed off in a few minutes. dissolve)? 7. A saturated solution of potassium nitrate is prepared at 600C using 200 ml_ of water. Bismuth arsenate. Not all compounds have the same solubility. A saturated solution of KNO 3 was made with 200g of water at 50 degrees celsius. 34749034749035. What will happen once these solutions are mixed? A. The solubility of KNO3 is 80g/100g water at 50 degrees and 10g/100g water at 0 degrees. The saturation temperature would then be higher. unsaturated. 94g of CuSO4. 22 M in MnSO4 monohydrate is best described as a(n) _____ solution. 50 degrees Celsius and a freezing point depression constant of 4. Nitrate Of Potash White Potassium Nitrate Powder KNO3 For Dry Place Storage. 0 Degrees Celsius 40. The x-axis shows values from 0 to 90. Solubility vs Concentration - Basic Introduction, Saturated Unsaturated and Supersaturated Solutions - Duration: 13:20. Potassium Nitrate is a crystalline salt, KNO3; a strong oxidizer used especially in making gunpowder, as a fertilizer, and in medicine. At 40 degrees C approximately 42 g of KNO3 will dissolve in water and and at 50 degrees C approximately 60 g. 285% O; All three compounds have the same empirical formula, CH 2O, but different molecular formulas. I attached the solubility curve. The solubility of CuSO4 is 60g/100g water at 50 degrees and 20g/100g water at 0 degrees. Example - in air with normal composition oxygen counts for approximate 20% of the total pressure. What is the rate of increase. Solubility in water: 1g/2. A mixture contains 13. Relative Humidity-Temperature Relationships of Some Saturated Salt Solutions in the Temperature Range 0 0 to 50 0 C 1 Arnold Wexler and Saburo Hasegawa. 75 g/100 mL (0 Degree C); 4. 1 mole of NaNO 3 in 250 g of water d. If 120 grams of sodium nitrate is dissolved in 100 grams of water at 20 degrees celcius, what type of solution is created? A unsaturated B Saturated c Supersaturated 4. Which solid would give a deposit of 20 g if a saturated solution in 100 g of water at 60 °C was cooled to 20 °C? 5. A saturated solution (23% w/v) freezes at -20. I remember answering this exact question yesterday. The y-axis shows values from 3. Solubility vs Concentration - Basic Introduction, Saturated Unsaturated and Supersaturated Solutions - Duration: 13:20. 3) The solubility of NH 3 decreases. 60g at 10 degrees C C. Would all of the compound dissolve?. Use the diagram to answer the following questions. Physical Science Mixtures Worksheet 1: Solubility Curves of KNO3 and NaCl ~\ Solubility of KNO3 and NaCl J-KNO3-NaCl 10 2030 40 50 60 70 Temperature (degrees Celsius) 80 90100 1. If 120 grams of sodium nitrate is dissolved in 100 grams of water at 20 degrees celcius, what type of solution is created? A unsaturated B Saturated c Supersaturated 4. At what temperature do KNO3 and NaCl have the same solubility? 20 degrees Celsius. , Bio-Rad Laboratories. 110 grams at 60 °C. 5 ml boiling water. 4Hz0, goes through a second in value. (b) Write the expression for the solubility product constant, Ksp, and calculate its value. What explain why solids become 10. Which of these substances is the most soluble at 72 degrees Celsius? When reading this table, any amounts below the solubility point. 50 X 10^2g/ 100g H2O at 70 degrees C. The composition of all three in mass percent is also the same (within rounding differences). When 50 grams of potassium chloride, KCl, is dissolved in 100 grams of water at 50 ºC, the solution can be correctly described as: Which of these salts decreases in solubility as the temperature increases. Sodium Chloride Solubility Temperature Solubility (g of solute/100 mL of H20) 0 35. That's why we humans cannot see God until we are made pure and translated into Heaven. As per the definition of solubility temperature, the solubility increases when the temperature increases where molecules are allowed to move faster at a higher temperature. 0g of sugar to 100g water at 20°C and stir, the solution will be _unsaturated_____. 49 g/100 ml (20 Degree C) Potassium per sulphate is the inorganic compound with the formula K 2 S 2 O 8. Industrial & Engineering Chemistry Research 2002, 41 (20) , 5109-5113. Connect the data points with a smooth curve. What mass (in grams) of KNO3 will crystallize out of solution if exactly 100. If all the solute could be dissolved in 100 grams of water at the stated temperature, would the resulting solution be unsaturated, saturated, or supersaturated? 1) 60g KCl at 70°C supersaturated [above line] 2) 90g KNO 3. Potassium nitrate is a chemical compound with the chemical formula K N O 3. Using the data in the above table, graph the solubility of the compound vs temperature. Cadmium fluoride. Excess solute will either precipitate out, or remain in an unstable dissolved state until the supersaturated solution is disturbed. 7 grams per 100 milliliters of water. On the same graph, plot the actual solubility of potassium nitrate in grams KNO 3 per 100 g water using data from the internet or other source (state the source of this data). A mixture contains 13. 00 As (s alpha‐gray) 0. Which of the salts shown on the graph has the greatest increase in solubility as the temperature increases from 30 degrees. The substances are listed in alphabetical order. Express this solubility in parts per million -I know the equation is. 140g of KNO3 in 200g of water at 60°C 4. The Solubility of Potassium Nitrate Aim To investigate how the solubility of Potassium Nitrate is affected by Temperature. 14 x 10-3 M at 25 °C. 0 g/ml of water). Formula State H f 0 S0 G f 0 Am 2O 3 (s) ‐1757. slope downward c. mL of water. asked by Lauren on October 6, 2014. For insoluble substances like silver bromide (AgBr), the molar solubility can be quite small. (b) Write the expression for the solubility product constant, Ksp, and calculate its value. 8ºC, it would be saturated. How many grams of NaNo3 per 100 grams of water would produce a supersaturated solution? A. A 20 degrees Celsius, the solubility of potassium nitrate is 30g in 100g of water. Also known as potassium peroxydisulfate or KPS, it is a white solid that is highly soluble in water. 73 Based on the data table, if 15 grams of solute is dissolved in 100 grams of water at 40°C, how many more grams of. Answer to: A saturated solution of KNO3 at 70 degrees C is cooled to 10 degrees C. The salt with a solubility is least affected by a change in temperature is 8. increase, how many more grams. As temperatures increases, the solubility also increases. Ksp (at 25 o C) #N#Aluminium hydroxide. Which substance’s solubility changes the least from 0 ºC to 100 ºC? NaCl 6. From there, draw a vertical line until it meets the solubility curve of KNO₃. 20 M KNO 3,. will all the potassium nitrate dissolve at 70 degrees c? if it does. If I dissolve 80 grams of KNO3 in 100 grams of water at 70 degrees celsius, what type of solution is created? A unsaturated B saturated C supersaturated 3. At 140g of KNO3 in 200g water at 76ºC, it would be saturated. The basic method is to measure the 100 mL of pure water as accurately as you can. KNO3; a strong oxidizer why-is-pbi2-not-soluble-5194540 5 / 5 based on. Barium selenate. But God DOES appear to some people who sincerely seek Him. What mass of a solid of precipitate is formed out of the. , it is observed the solubility of KNO3 at 40 °C is 62 g per 100 g of water whereas the solubility of KNO3 at 0 °C is 12 g per 100 g of water. 43 x 10-3 gram per liter at 25 °C. For solubilities at. Why do the temperatures on the graph only go from 0º C to 100º C ? water is frozen below 0 celcus and is gaseous above 100 celcius 2. why-is-pbi2-not-soluble-5194540 5 / 5 based on 2 votes. Calculate the solubility of the solution at 50 degree Celsius. A saturated solution of KNO3 is formed in 100 g water at 75 degrees C. Here, one of the products, At 20 degrees Celsius the solubility of KI is 140-148 grams per 100 grams of water. 9 30 36 40 36. It is a potassium salt and an inorganic nitrate salt. At 20 degrees Celsius the solubility of KI is 140-148 grams per 100 grams of water. 3=> Explain how you can use a solubility curve to determine what type of solution will be formed by mixing 100 g KNO3 in 100 g of water? 4=> List the three ways we can influence the rate at which a solute dissolves in a solvent, and be able to discuss those and understand why they effect the rate. Solubility is often measured as the grams of solute per \(100 \: \text{g}$$ of solvent. 2 grams per mole, and its density is 4. The existence of solid phases of potassium nitrate and chromium(III) nitrate nonahydrate was confirmed by. If some solute precipitates as the saturated solution cools to 40 degrees C, what mass of solid KNO3 should form. O)X-axis: Temperature (Celsius) Substances: Compound being dissolved in water (H. temperature range of 0oC to 100oC. A solution of potassium chlorate, KClO 3, has 20 grams of the salt dissolved in 100 grams of water at 70 ºC. How many grams (if any) of potassium nitrate will precipitate from a solution containing 85g of KNO3 and 100g of water at 50 degrees celsius if the solution is cooled to 20 degrees?. Which of the following has a solubility that decreases as temperature increases?. Is there more KNO3 or NaCl dissolved at 5 ° C? 2. 7135% H, 53. At 25°C, gaseous SO 2 Cl 2 decomposes to SO 2 (g) and Cl 2 (g) to the extent that 14. Which of these substances is the most soluble at 72 degrees Celsius? When reading this table, any amounts below the solubility point. 7 grams per 100 milliliters of water. This process is close to or at equilibrium at 25°C. It occurs in nature as a mineral, niter. 140 g of KNO 3 in 200 g of water at 60°C 4. THE THERMODYNAMICS OF POTASSIUM NITRATE DISSOLVING IN WATER1 OBJECTIVE In this experiment, the changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) of the potassium nitrate (KNO3) dissolving reaction will be determined by measuring the equilibrium constant (K sp) at different temperatures. Redox & Coordination Kf. Use the solubility graph below to answer the following questions: a) Which substance has the greatest solubility at 30 C? NH 4 Cl b) What is the solubility of KCl at 60 C? 40 g/100 g H 2 O (40%) c) A sample of KNO 3 with a mass of 50. On the same graph, plot the actual solubility of potassium nitrate in grams KNO 3 per 100 g water using data from the internet or other source (state the source of this data). (i) Write the equation for the dissociation of AgCl(s) in water. How many grams were dissolved? How many grams could be dissolved if the temperature was raised to 100 degrees celsius? 23. This can be calculated from thermodynamics, given two constants - the enthalpy of dissolution and the entropy of dissolution. Ba (IO 3) 2 x H 2 O. A mixture contains 13. Note that for gases in combination with other gases - like oxygen in air - the partial pressure of the gas must be used. 1 g of this compound is mixed with 1. Which two substances have the same solubility at 71 degrees C? 128g. Which substance’s solubility changes the least from 0 ºC to 100 ºC? NaCl 6. From the figure 1. Will all of the potassium nitrate dissolve at 70 degrees Celsius?. (a) At 10°C, 8. Solubility curves for several salts are shown below: Make sure your graph is made following the graphing guidelines given in your lab manual. 94g of CuSO4. 28 x 10¯ 4 mol/L Comment: The value of s is the molar concentration of the carbonate ion. 7 grams per 100 milliliters of water. 0 mL of water. 53 grams per cubic centimeter. in solubility in grams per degree (in other words, for every degree of temp. Notice how NaCl's solubility is relatively constant regardless of temperature, whereas Na2SO4's solubility increases exponentially over 0-35 degrees Celsius and then abruptly begins to decrease. Using Raoult's Law, we know that the vapor pressure of pure water (P˚) multiplied by the mole fraction (X) of the solute gives the vapor pressure of the solvent above the solution (P). D) increases the boiling point. 0 Degrees Celsius 20. Commonly, solubility data is given for 25°C. O)X-axis: Temperature (Celsius) Substances: Compound being dissolved in water (H. How many grams of NaCl are dissolved at 40 °C? 4. no of moles= 29. (a) Write a balanced equation for the solubility equilibrium. 2 grams per mole, and its density is 4. Water solubility table (chart) of salts (ions) in SolubilityOFthings. At 50 °C: a saturated solution of KNO 3 or an unsaturated solution of NaNO 3. That's why we humans cannot see God until we are made pure and translated into Heaven. asked by Lauren on October 6, 2014. The thermodynamics of the solubility of borax 4. , it is observed the solubility of KNO3 at 40 °C is 62 g per 100 g of water whereas the solubility of KNO3 at 0 °C is 12 g per 100 g of water. 10) The solubility of the solution would be lower because the temperature was too low. 0 mL of water. A precipitate is an insoluble solid formed by the reaction of two or more solutions of soluble compounds. 9% Potassium Nitrate Powder 100% Water Soluble KNO3. Using the data in the above table, graph the solubility of the compound vs temperature. Is there more KNO3 or NaCl dissolved at 5 ° C? 2. Ksp and Solubility 1 1a. The table below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at 1 atmosphere pressure. Units of solubility are given in grams per 100 millilitres of water (g/100 ml), unless shown otherwise. The solubility of CuSO4 is 60g/100g water at 50 degrees and 20g/100g water at 0 degrees. Salts are usually more soluble at elevated temperatures than at lower temperatures. 9) The solubility would be higher if water from the test tube evaporated because there would be less water for the KNO3 to dissolve into. A mixture contains 13. (90-1) The solubility of iron(II) hydroxide, Fe(OH)2, is 1. ave b~en determined in air in equi hbllum with sat urated ~alt solutIOns of llthlUm chlonde, L1C[·H20 ; magnesium chloride. A saturated solution of KNO3 is formed in 100. So i know the answer to the question I just don't know how to explain it. Use Henry’s law to determine the solubility of oxygen when its partial pressure is 20. What two salts have the same degree of solubility at approximately 19oC? How many grams of potassium chlorate (KCl) must be added to 100 mL of water to produce a saturated solution at 50oC? A saturated solution of potassium nitrate (KNO3) is prepared at 60oC using 100. 6L) and I add 50g of K2CrO4 to the solution. 1) How many moles of NaI can be dissolved in 100mL of H2O at 25 degrees Celcius? 2) What would be the molarity of a saturated aqueous. ? How many grams of water are needed to prepare a saturated solution containing 80. mL of water. Define the terms precipitation and solubility. 6 g of solute/100 g of H2O in 20 Celsius. The solubility of KNO3 is 80g/100g water at 50 degrees and 10g/100g water at 0 degrees. If the temperature falls even the tiniest bit below 57°C, the water will no longer dissolve as much potassium nitrate - and so some crystallises out. Barium selenate. Solubility of Sucrose: 179 grams per 100 milliliters of water at 20 degrees Celsius. The inverse of the Henry's law constant, multiplied by the partial pressure of the gas above the solution, is the molar solubility of the gas. At what temperature do KNO3 and NaCl have the same solubility? 20 degrees Celsius. 2 grams per mole, and its density is 4. Kno3 Dissolved In Water. Use the solubility curve graph to determine if a solution is unsaturated, saturated, or supersaturated, when 80 grams of KI are dissolved in 100 grams of water at 20°C. Ba (OH) 2 x 8H 2 O. The solution will appear: solute will be completed dissolved. Solubility of solute in solvent at that temperature. Potassium nitrate is the inorganic nitrate salt of potassium. ° C: 247 g/100 g water 4. Construct a solubility curve using the mass of solute that will dissolve in 100 g of water at a specified temperature. The dissolved compound would crystallize from the solution due to the difference in solubility at high and low temperatures. Supersaturated: A solution that has an excess of solute beyond the solubility point for a given temperature. You could contrast the KNO3 curve with the NaNO3 curve, which is nearly flat, and demonstrate how sodium nitrate dug from guano deposits is converted to KNO3. Upon hitting submit, K sp (1. 0g/100g of H2O. Thus, the solubility of KNO₃ at 50 °C is 90 g/100 g water. Is there more KNO3 or NaCl dissolved at 55 ° C? 3. Chlorfenapyr Insecticide. Solubility product constant ( Ksp) (or the solubility product) is the product of the molar concentrations of the constituent ions, each raised to the power of its stoichiometric coefficient in the equilibrium equation. Chemistry The solubility of KNO3 is 80g/100g water at 50 degrees and 10g/100g water at 0 degrees. _____ 80 °C _____ 10 x 3 = 30 g KClO 2b. This data in the table is relevant only to the temperature given for the table. Define solubility. Ba (IO 3) 2 x H 2 O. 8388879824) will be used to calculate the equilibrium concentration for all species. asked by Emily on March 20, 2011. Solubility tables (tables of solubility) usually tabulate the maximum mass in grams of the solute that can be dissolved in 100 mL of water. [2 C s] 2 [C s] = 6. C is cooled to 10 degrees C. We started with the solubility product expression for Ag 2 S. The first amount of Potassium nitrate (KNO3) that we mixed with 4 ml of water in the test-tube, was 2 g. Plot solubility in grams per 100 grams of water on the y-axis and temperature on. Solubility Curves: a. 28 degrees Celsius. Solubility slightly increases with temperature, almost linearly from 0. How many grams were dissolved? How many grams could be dissolved if the temperature was raised to 100 degrees celsius? 23. g of water. Precipitation is the act of precipitating or forming a precipitate. Solubility question from Solubilty Curve. The solubility of sodium chloride is the square root of the solubility constant, K sp. (b) Write the expression for the solubility product constant, Ksp, and calculate its value. mL of water. Kno3 Dissolved In Water. Experiment - The Solubility of Potassium Nitrate Aim To investigate how the solubility of Potassium Nitrate is affected by Temperature. 94g of CuSO4. A) increase B) decrease C) remain constant Answer: B 6. Answer the following questions relating to the solubility of the chlorides of silver and lead. A student mixes 20 g of a salt in 100 g of water at 20 degrees Celsius and obtains a homogeneous solution. enthalPy of solution of eleCtrolytes This table gives the molar enthalpy (heat) of solution at infinite dilution for some common uni-univalent electrolytes. no of moles= reacting mass. 2) The solubility of NH 3 increases, and the solubility of KCl increases. 8g of K2SO4 (potassium sulfate). This process is close to or at equilibrium at 25°C. The solubility of a solid in a solution is dependent on temperature. 90g at 30 degrees C B. Consider the reaction 2C3H6 + 9O2 6CO2 + 6H2O. , Ce2(SO4)3: When 30 grams of potassium nitrate, KNO3, is dissolved in 100 grams of water at 20 ºC, the solution can be correctly described as:, saturated: A solution of potassium chlorate, KClO3, has 20 grams of the salt dissolved in 100 grams of water at 70 ºC. Section 10: Stability and Reactivity Data. The solubility of sodium chloride is the square root of the solubility constant, K sp. 9 grams per 100 ml, and the solubility of KH2PO4 is 23 grams per 100 ml. the solubility of potassium nitrate in 70 degrees Celsius water is about 134 g KNO3 per 100 g water Asked in Chemistry , Elements and Compounds , Salt (Sodium Chloride) What is the solubility of. Water solubility table (chart) of salts (ions) in SolubilityOFthings. 225 kg solvent) = 0. , it is observed the solubility of KNO3 at 40 °C is 62 g per 100 g of water whereas the solubility of KNO3 at 0 °C is 12 g per 100 g of water. A saturated solution of KNO 3 was made with 200g of water at 50 degrees celsius. 60 g of KNO 3 in 100 g of water at 70°C c. An increase in atmospheric pressure causes an increase in the solubility of KCl. How many grams of NaNo3 per 100 grams of water would produce a supersaturated solution? A. If some solute precipitates as the saturated solution cools to 40 degrees C, what mass of solid KNO3 should form. Cadmium carbonate. This solution is supersaturated. 2×10 –20: Mercury(II) hydroxide: Hg(OH) 2: 3. Therefore, elemental analysis will give us only the empirical formula. How much KNO3 solute is saturated at 40 degrees? Solubility curves 2 DRAFT. 5 × 10-4 M in calcium ion and 2. 5 °C (5 °F). So, 400 grams can hold 20g x 4 = 80 grams of HNO3. Therefore, we will read the graph as follows: 1- Find the KBR curve which is the green one 2- Find the point on that line that corresponds to temperature. Put the following in order from most soluble to least soluble at 30 degrees C KNO3 NaNO3 SO2 KCl. SOLUBILITY CURVE WORKSHEET KEY Use your solubility curve graphs provided to answer the following questions. 9th - 12th grade. Barium chromate. 0 g of NaCl in 100 g of H2O at 20 degrees Celsius, how many grams of water are needed. , it is observed the solubility of KNO3 at 40 °C is 62 g per 100 g of water whereas the solubility of KNO3 at 0 °C is 12 g per 100 g of water. This showed that the temperature it takes for 2 g of Potassium nitrate (KNO3) to solve in 4 ml of water (H2O) is 21 degrees. 3 g KNO3 is soluble in 35 g H2O @ 20 C. 7 grams per 100 milliliters of water. All four substances have higher solubility at higher temperatures in the range from 0 to 100 degrees Celsius. 00 Acetone 0. 2 g of KNO3 will precipitate out. the solubility of lead(II) nitrate and potassium nitrate is the same at about 50°C (approximately 80 g per 100 g water, where the solubility curves of these substances cross). The solubility of micro ferts varies from chelate to chelate, and unfortunately there is little information about the solubility of Plantex CSM+B. in 35 g H2O @ 0. 2g of KNO3 (potassium nitrate) and 4. At 25°C and 101. Use the solubility data for potassium nitrate at 0 C to determine the mass of potassium nitrate that will theoretically dissolve in 15. Which of the salts shown on the graph is the least soluble in water at 10oC? 2. Commonly, solubility data is given for 25°C. At 57°C, you hit the solubility curve. The solubility of KNO3 is 80g/100g water at 50 degrees and 10g/100g water at 0 degrees. What do all of the compounds that decreased in solubility over the temperature range in the graph. 8g of K2SO4 (potassium sulfate). The solubility of CuSO4 is 60g/100g water at 50 degrees and 20g/100g water at 0 degrees. If all of the solute NaCl at 20 °C _____ 6. Correct answers: 1 question: VUICII Suvstance on the graph is least soluble at 10°C? KI NaNO3 NH3 OKNO3 NH4CI OKCI NACI OKCIO3 Ce2(SO4)3 A mass of 80 g of KNO3 is dissolved in 100 g of water at 50 °C. Chemistry The solubility of KNO3 is 80g/100g water at 50 degrees and 10g/100g water at 0 degrees. The solubility of KNO3 is 155 g per 100 g of water at 75 degrees celcius and 38. Connect the data points with a smooth curve. Circle and connect the points. 3% of the original SO 2 Cl 2 (by moles) has decomposed to reach equilibrium. -In two test tubes, put exactly 5 mL water in each. The substances are listed in alphabetical order. grams of water at 50°C to produce a saturated solution? (1)decreasing the pressure (2)increasing the pressure (3)decreasing the temperature (4)increasing the temperature 20. Is the process kno3 dissolving in water spontaneous at all temperatures studied? Answers: 1 Get Other questions on the subject: Chemistry. slope downward c. What mass of a solid of precipitate is formed out of the. 3 times NaCl, match the solubility of potassium dichromate, K 2 Cr 2 O 7? answer choices. 2 Copper Sulfate Solubility Temperature Solubility (g of solute/100 mL of H20) 0 23 10 27. Define solubility. 8g of KNO3 and 1. Low Toxicity Chlorfenapyr Insecticide 98% TC 10% EC 24% EC 36% EC. 140g of KNO3 in 200g of water at 60°C 4. Go across to the y axis and read the solubility for that salt. 8ºC, it would be saturated. As per the definition of solubility temperature, the solubility increases when the temperature increases where molecules are allowed to move faster at a higher temperature. ___ 4) According to the Solubility Curves chemistry reference table, how does a decrease in temperature from 40 DC to 20 DC affect the solubility of NH 3 and KCl? 1) The solubility of NH 3 increases, and the solubility of KCl decreases. (90-1) The solubility of iron(II) hydroxide, Fe(OH)2, is 1. Temperature (∘C) Solubility (g/100 g H2O) 20 11. 11)The solubility of MnSO4 monohydrate in water at 20 °C is 70. _____ 80 °C _____ 10 x 3 = 30 g KClO 2b. 140 g of KNO 3 in 200 g of water at 60°C 4. The molar solubility of a substance is the number of moles that dissolve per liter of solution. A mixture contains 13. But KNO3 on the skin will not be a problem if washed off in a few minutes. asked by Lauren on October 6, 2014. In a 100-mL beaker, prepare a saturated solution of borax by adding roughly 20 g of borax to 80 mL of distilled water. Solubility of pure gases like. The solubility product works as follows: In a water solution at equilibrium with a slightly soluble ionic compound, the product of the concentration of the ions, raised to the power of its coefficient in the solubility equation, is a constant. pdf), Text File (. 53 grams per cubic centimeter. Pb(NO3)2 is the formula of lead(II) nitrate, an inorganic compound whose water solubility is 52 grams per 100 milliliters at 20 degrees Celsius and 127 grams per 100 milliliters at 100 degrees Celsius. 20 g NaCl at 90 degrees Celsius Solubility of NaCl at 100°C is 384 g/L i. Therefore, solubility is the dependent variable and as such is placed on the vertical or y-axis of the graph. I have all of my data and the question is asking me to: 1) Show an example calculation of how you determined the solubility value in g/100g H2O for your mass of KClO3? This is my lab data: Mass of KClO3= 17g Trial 1 temperature= 51 degrees C Trial. increase appreciably with temperature, since at 100 °C, the solubility is 384 mg/mL. ___ 4) According to the Solubility Curves chemistry reference table, how does a decrease in temperature from 40 DC to 20 DC affect the solubility of NH 3 and KCl? 1) The solubility of NH 3 increases, and the solubility of KCl decreases. C 7H 5N 3O 6 49. A solution of potassium chlorate, KClO 3, has 20 grams of the salt dissolved in 100 grams of water at 70 ºC. Bismuth arsenate. 3=> Explain how you can use a solubility curve to determine what type of solution will be formed by mixing 100 g KNO3 in 100 g of water? 4=> List the three ways we can influence the rate at which a solute dissolves in a solvent, and be able to discuss those and understand why they effect the rate. go straight across 7. 8g of KNO3 and 1. Chemistry The solubility of KNO3 is 80g/100g water at 50 degrees and 10g/100g water at 0 degrees. Here, one of the products, At 20 degrees Celsius the solubility of KI is 140-148 grams per 100 grams of water. The formula weight of MnSO4 monohydrate is 168. At 10 °C: a saturated solution of KNO 3 or a saturated solution of CaCl 2. The value of the solubility constant depends only on. The equation is ln(K sp) = -ΔH 0 /RT +ΔS 0 /R. Question: A Student Mixes 20 G Of A Salt In 100 G Of Water At 20 Degrees Celsius And Obtains A Homogeneous Solution.
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## WeBWorK Main Forum

### One random seed can't generate enough comparison points

by Michael Shulman -
Number of replies: 2
It seems that for the question /Library/UCSB/Stewart5_3_4/Stewart5_3_4_28.pg in the problem library, the random seed 1157 always results in "Can't generate enough valid points for comparison". Is this a bug? The formula is defined for all positive values of x.
In reply to Michael Shulman

### Re: One random seed can't generate enough comparison points

by Michael Shulman -
If no one knows, can anyone at least give me some help for debugging? E.g. how can I find out what comparison points it is trying to generate?
In reply to Michael Shulman

### Re: One random seed can't generate enough comparison points

by Davide Cervone -
The default range of values is -2 to 2 for MathObjects (and -1 to 1 for the traditional checkers), and so it is possible for all the random points to be negative. The problem needs to be modified to restrict to positive values.

You can add diagnostics=>1 to the cmp() call in order to get debugging output about the points used and their values, but this only works when sufficient points actually are found.

In any case, these issues are better handled via the WeBWorK Bugzilla site rather than this question-answer site.


text:
Under the auspices of the Computational Complexity Foundation (CCF)

REPORTS > DETAIL:

### Paper:

TR05-113 | 12th September 2005 00:00

#### On the Hardness of Range Assignment Problems

TR05-113
Authors: Bernhard Fuchs
Publication: 9th October 2005 04:38
Keywords:

Abstract:

We investigate the computational hardness of the {\sc Connectivity},
the {\sc Strong Connectivity} and the {\sc Broadcast} type of Range
Assignment Problems in $\R^2$ and $\R^3$.
We present new reductions for the {\sc Connectivity} problem, which
are easily adapted to suit the other two problems. All reductions
are considerably simpler than the technically quite involved ones
used in earlier works on these problems. Using our constructions, we
can for the first time prove NP-hardness of these problems for
\emph{all} real distance-power gradients $\alpha > 0$ (resp.\
$\alpha > 1$ for {\sc Broadcast}) in 2-d, and give improved lower
bounds on the approximation ratios of all three problems in 3-d for
all $\alpha > 1$. In particular, we derive the overall first
APX-hardness proof for {\sc Broadcast}. This was an open problem
posed in earlier work in this area, as was the question whether {\sc
(Strong) Connectivity} remains NP-hard for $\alpha = 1$.
Additionally, we give the first hardness results for so-called


text:
## Dual-Polarimetric Descriptors From Sentinel-1 GRD SAR Data for Crop Growth Assessment

Narayanarao Bhogapurapu, Subhadip Dey, Avik Bhattacharya, Dipankar Mandal, Juan M. Lopez-Sanchez, Heather McNairn, Carlos López-Martínez, Y.S. Rao, “Dual-polarimetric descriptors from Sentinel-1 GRD SAR data for crop growth assessment,” ISPRS Journal of Photogrammetry and Remote Sensing, vol. 178, p. 20-35, Aug 2021

Summary

➲Full paper

Accurate and high-resolution spatio-temporal information about crop phenology obtained from Synthetic Aperture Radar (SAR) data is an essential component for crop management and yield estimation at a local scale. Crop growth monitoring studies seldom exploit complete polarimetric information contained in dual-pol GRD SAR data. In this study, we propose three polarimetric descriptors: the pseudo scattering-type parameter (θc), the pseudo scattering entropy parameter (Hc), and the co-pol purity parameter (mc) from dual-pol S1 GRD SAR data. We also introduce a novel unsupervised clustering framework using Hc and θc with six clustering zones to represent various scattering mechanisms. We implemented the proposed algorithm on the cloud-based Google Earth Engine (GEE) platform for Sentinel-1 SAR data. We have shown the sensitivity of these descriptors over a time series of data for wheat and canola crops at a test site in Canada. From the leaf development stage to the flowering stage for both crops, the pseudo scattering-type parameter θc changes by approximately 17°. Moreover, within the entire phenology window, both mc and Hc varies by about 0.6. The effectiveness of θc and Hc to cluster the phenological stages for the two crops is also evident from the clustering plot. During the leaf development stage, about 90% of the sampling points were clustered into the low to medium entropy scattering zone for both the crops. Throughout the flowering stage, the entire cluster shifted into the high entropy vegetation scattering zone. Finally, during the ripening stage, the clusters of sample points were split between the high entropy vegetation scattering zone and the high entropy distributed scattering zone, with >55% of the sampling points in the high entropy distributed scattering zone. This innovative clustering framework will facilitate the operational use of S1 GRD SAR data for agricultural applications.

## A Multi-Frequency SDR-Based GBSAR: System Overview and First Results

Amézaga, Adrià; López-Martínez, Carlos; Jové, Roger. 2021. “A Multi-Frequency SDR-Based GBSAR: System Overview and First Results” MDPI Remote Sens. 13, no. 9: 1613

Summary

This work describes a system-level overview of a multi-frequency GBSAR built around a high performance software defined radio (SDR). The main goal of the instrument is to be employed as a demonstrator and experimental platform for multi-frequency GBSAR campaigns. The system is capable of operating in P, L, C and X-bands, and signal generation and digital signal processing are customizable and reconfigurable through software. An overview of the software and hardware and implementations of the system are presented. The operation of the system is demonstrated with two measuring campaigns showing focused amplitude images at different frequencies. It is shown how the usage of SDR for GBSAR systems is a viable design option.

## A Model-free Four Component Scattering Power Decomposition for Polarimetric SAR Data

S. Dey, A. Bhattacharya, A. C. Frery, C. López-Martínez and Y. S. Rao, “A Model-free Four Component Scattering Power Decomposition for Polarimetric SAR Data,” in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Early Access, 2021

Summary

Target decomposition methods of polarimetric Synthetic Aperture Radar (PolSAR) data explain scattering information from a target. In this regard, several conventional model-based methods utilize scattering power components to analyze polarimetric SAR data. However, the typical hierarchical process to enumerate power components uses various branching conditions, leading to several limitations. These techniques assume \textit{ad hoc} scattering models within a radar resolution cell. Therefore, the use of several models makes the computation of scattering powers ambiguous. Some common issues of model-based decompositions are related to the compensation of the orientation angle about the radar line of sight and the negative power components’ occurrence. We propose a model-free four-component scattering power decomposition that alleviates these issues. In the proposed approach, we use the non-conventional 3D Barakat degree of polarization to obtain the scattered electromagnetic wave’s polarization state. The degree of polarization is used to obtain the even-bounce, odd-bounce, and diffused scattering power components. Along with this, a measure of target scattering asymmetry is also proposed, which is then suitably utilized to obtain the helicity power. All the power components are roll-invariant, non-negative and unambiguous. In addition to this, we propose an unsupervised clustering technique that preserves the dominance of the scattering power components for different targets. This clustering technique assists in understanding the importance of diverse scattering mechanisms based on target characteristics. The technique adequately captures the clusters’ variations from one target to another according to their physical and geometrical properties.

## Second Multi-Frequency GBSAR Test Campaing, Castell de Subirats, Spain

In June 22nd, 2020, we continued the field test of our new multi-frequency GBSAR system, developed in a joint effort of Balamis and the Remote Sensing Laboratory of the Universitat Politècnica de Catalunya, as the PhD of Adrià Amézaga under the aegis of the Industrial Doctorate Programs of the Generalitat de Catalunya and the Spanish Ministry of Science, Innovation and Universities.

This time, the system was fully operational and we tested its performances for forest monitoring at X-, C-, L-band frequencies and finally P-band. The test area is located right next to the Castell de Subirats (Subirats Castle), in the outskirts of the Barcelona city.

The video below shows the four 3-hour time-series of $|S_{vv}|$ images at X-, C-, L- and P-band frequencies measured this day.  One can observe how signal stability increases as the frequency gets lower. This demonstrates that vegetation is transparent at lower frequencies, mainly L- and P-band, so we are observing the soil and the rocky structures under the vegetation.

## Coastline Detection Based on Sentinel-1 Time-Series for Ship and Flood Monitoring Applications

R. Pelich, M. Chini, R. Hostache, P. Matgen and C. López-Martínez, “Coastline Detection Based on Sentinel-1 Time Series for Ship- and Flood-Monitoring Applications,” in IEEE Geoscience and Remote Sensing Letters, Early Access, 2020

Summary

This letter addresses the use of the Sentinel-1 time series with the aim of proposing an automatic and unsupervised coastline detection method that averages the dynamical variations of coastal areas over a limited period of time, e.g., one year. First, we propose applying a temporal averaging filter that allows the temporal variations in coastal areas, e.g., due to tides or vegetation, to be encapsulated, and, at the same time, the speckle to be reduced, without decreasing the spatial resolution of the synthetic aperture radar (SAR) time series. Then, based on the distinctive backscattering values of the sea and land pixels, we will employ an iterative hierarchical tiling method in order to accurately characterize the two classes using bimodal distribution. The distribution is then segmented by a thresholding and region-growing procedure to separate the sea and land classes. A large-scale quantitative comparison between the SAR-derived and open street map (OSM) coastlines allows for a numerical evaluation of the results, i.e., an overall agreement ranging from 80% to 90%. In addition, Sentinel-2 images are used to evaluate the estimated SAR coastline qualitatively. Furthermore, the benefits of having an accurate SAR coastline are shown in the case of two well-known Earth observation-monitoring applications, ship detection, and floodwater mapping.


text:
# How do I generate a list of n unique random numbers in Ruby?

I am trying to create a randomly generated array of x numbers with no duplicates. I am choosing numbers, one at a time, then comparing each new number to the numbers already in the array.

Here is my code. At the end I should have an array of seven numbers, none that match, but sometimes I get a nil:

array = [] #DEFINES THE ARRAY

array[0] = rand(10)  #THIS CHOOSES FIRST NUMBER (FN) AND PUTS IT IN THE FIRST ARRAY SPOT
p "fn = #{array[0]}"

for i in 1..6  #START OF FOR LOOP TO GET 6 NUMBERS IN THE ARRAY - WHY 6?  THE FIRST NUMBER THAT POPPED IN MY HEAD

p "Iteration #{i} -------------------------"  # THIS IS JUST SO I KNOW WHERE I AM IN THE LOOPS

@x = rand(10)  #THIS CHOOSES THE NEXT NUMBER AND ALL NUMBERS AFTER

array.each do |uc|  # THIS IS THE LOOP THAT COMPARES ALL NUMBERS

@type = @x == uc ? "yes" : "no"  #DOES THE CHOSEN NUMBER EQUAL ANY NUMBER IN THE ARRAY

p "does #{uc} = #{@x}? #{@type}"
if @type == "yes"  # IF THE COMPARE IS TRUE, I DON'T WANT ANYTHING DONE.  IT WILL CYCLE THRU AND GET A NEW NUMBER

i = 1
p "YES #{@x} = #{uc}"
break
end  #END OF IF YES
end  #END OF ARRAY EACH

if @type == "no"  #IF NO, PUT NEXT NUMBER (@X) INTO THE NEXT ARRAY SPOT.

p "in last if type= #{@type}"  #THESE STATEMENTS JUST PRINT OUT THE DIFFERENT VARIABLES SO I KNOW I AM GETTING WHAT I EXPECT

p "in last if x = #{@x}"
p "in last if i = #{i}"
@x = array[i]  #THIS "SHOULD" FILL THE NEXT ARRAY SPOT - BUT DOESN'T SEEM TO

p "#{array[i]} is in the array"  #THIS PRINT OUT IS BLANK - STATEMENT ABOVE DID NOT WORK.

p array[i]
end  #END OF IF NO

end  #END OF FOR LOOP

p array #PRINTS OUT THE CONTENTS OF THE ARRAY

I know there are probably quicker and easier ways to do this, but I am starting out with what I know, and building up.

-

I don't understand what you really want, but this simple one-liner generates an array of ten elements (from 1 to 10) with a random order. Tweak it to meet your needs:

(1..10).to_a.shuffle
#=> [4, 10, 1, 7, 3, 5, 8, 2, 9, 6]

-
This is great, and I thank you. – Kyzer Jan 15 '13 at 17:09
Actually it had to be (0...10).to_a.shuffle.take(7). – Nakilon Jan 15 '13 at 18:54
+1 "zen-like". Nicely done. – the Tin Man Jan 16 '13 at 3:56
Why did u append @steenslag answer? – Nakilon May 22 '13 at 14:10
@Nakilon. Ok, deleted. – tokland May 22 '13 at 18:01

The sample method does what you want:

(1..10).to_a.sample(7) #=> [2, 9, 1, 6, 8, 10, 4]

-
1. Why do you put empty lines everywhere? They don't make your code more readable.
2. If you used @ not because you are writing classes, but just to fix scope problems, you may try either use $ instead or even better define type variable outside the nested loop (before array.each do |uc|). 3. And the main thing. Ruby's loops are more highlevel, than in, for example, C. And you can't directly change the i value. So you should use keyword redo to repeat the iteration. http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_containers.html 4. You may use puts instead of p to get rid of "", but it may need STDOUT.sync = true fix under Windows. 5. Also you need array[i] = x instead of x = array[i]. If you aren't experienced in programming, I would recommend to start with C/C++. So here is your program. Not refactored yet, but fixed. array = [] array[0] = rand 10 puts "fn = #{array[0]}" for i in 1..6 puts "Iteration #{i} -------------------------" x = rand 10 array.each do |uc|$type = x == uc ? "yes" : "no"
puts "does #{uc} = #{x}? #{$type}" if$type == "yes"
puts "YES #{x} = #{uc}"
break
end
end
if $type == "no" puts "in last if type= #{$type}"
puts "in last if x = #{x}"
puts "in last if i = #{i}"
array[i] = x
puts "#{array[i]} is in the array"
p array[i]
else
redo
end
end
p array

### Now refactoring:

You need to know, that Ruby arrays have a method #include?, which you may use instead of loop. We will lose debugging ability a bit, but it makes program more pretty, and now we don't need to make type variable global.

array = []
array[0] = rand 10
puts "fn = #{array[0]}"
for i in 1..6
puts "Iteration #{i} -------------------------"
x = rand 10
type = array.include?(x) ? "yes" : "no"
puts "does array include #{x}? #{type}"
if type == "no"
puts "in last if type=#{type}, x=#{x}, i=#{i}"
array[i] = x
puts "#{array[i]} is in the array"
else
redo
end
end
p array

Then get rid of "yes" and "no", and use native Ruby true and false. And you may add tap to any object for debugging purposes - this universal method returns the object itself after execution, so you will be able to comment it later via putting # before .tap (when you don't need debug output) without breaking the program.

array = []
array[0] = rand 10
puts "fn = #{array[0]}"
for i in 1..6
puts "Iteration #{i} -------------------------"
x = rand 10
if (type = array.include? x).tap{ puts "does array include #{x}? #{type : "yes" : "no"}" }
redo
else
puts "in last if type=#{type}, x=#{x}, i=#{i}"
array[i] = x
puts "#{array[i]} is in the array"
end
end
p array

But actually you print the type the second time only when it is false, so don't do it. Also we don't need else in this case, because redo will throw us away from this iteration. And actually we can start from iteration 0 and then change for to times. But we will lose the puts "fn=" (I don't know, whether you really need it).

array = []
7.times do |i|
puts "Iteration #{i} -------------------------"
x = rand 10
redo if array.include?(x).tap{ |type| puts "does array include #{x}? #{type ? "yes" : "no"}" }
puts "x=#{x}, i=#{i}"
array[i] = x
puts "#{array[i]} is in the array"
end
p array

-
Outstanding. Thank you very much for showing me how my code was wrong in the first place, and then going farther by simplifying it in easy to understand steps. I learned much, and I greatly appreciate it. – Kyzer Jan 15 '13 at 17:12