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## Fixing LibreOffice Document Graphic File Paths

It turns out that if you put convenient symlinks in your directories, then use them to build a LibreOffice document, LO will cheerfully put those paths into the graphic file links inside its XML files. That will produce horrible breakage on a new system without those links. We’ve come to the conclusion that the only way to keep LO happy is to create a Pictures directory in whatever directory holds the document file, then put all of the document’s image files into that directory, and make sure LO stores relative paths. Of course, this leaves us with the prospect of updating a whole bunch of existing (and, alas, horribly broken) documents by hand, which is unappealing. My previous solution worked for a single file, but now it’s time for some scripting…

This would probably be easier in Python, but Bash works fine after you get the quoting straightened out. This script builds several other scripts that actually do the heavy lifting, because that way you can inspect the scripts before running them to verify that you’re not about to make a bad situation much, much worse. I recommend copying the presentations into another directory, running this script, check the output scripts, run them by hand, and then copy the fixed files and the Pictures directory back where they belong.

You must tweak the actual paths to the pictures to match your situation; for these documents, one simple change sufficed for all the image files. Those paths are not variables, because I can barely keep the quoting straight without adding another layer of indirection. Make sure all the paths match up, verify the scripts before you run them, and don’t trust anything you see.

CAUTION: It’s highly likely that the multiple levels of character escaping required to make these listings appear correctly on the screen will produce incorrect results when copied-and-pasted. You can download the script file as FixGraphics.sh.odt, which is a bare-ASCII TXT file (which you must rename to eliminate the ODT extension, then make executable as a shell script), to see how it compares.

The main FixGraphics.sh script, with some key lines highlighted:

#!/bin/bash

echo "Extract list of images from all ODP files"
rm images.txt
for f in *odp
do
unzip -p "$f" content.xml | sed 's/></>\n</g' | grep Cameras | cut -d \" -f 2 | sort -u >> images.txt done echo "Make source file name list" # strip off leading relative pathing, set actual absolute path, un-quote blanks and special characters, add quotes sed 's/..\/..\/..\/../\/mnt/' images.txt | sed 's/%20/ /g' | sed 's/&/\&/g' | sed 's/^.*/\"&\"/' > source.lst echo "Make target file name list" # set relative to current directory sed 's/\/mnt\/bulkdata\/Cameras\/MCWN/\.\/Pictures/' source.lst > target.lst echo "Make target directory list" # must add trailing quote stripped by dirname rm dirs.lst cat target.lst | while read tline ; do tdir=dirname "$tline"
echo ${tdir}\" done > dirs.lst echo "Create target directory structure script" rm mkdirs.sh sort -u dirs.lst | while read dline ; do echo mkdir --parents${dline}
done > mkdirs.sh
chmod u+x mkdirs.sh

echo "Create image file copy script"
rm cpjpgs.sh
cat dirs.lst | while read dline ; do
echo cp -n -t ${dline} done > cptemp.txt paste cptemp.txt source.lst > cpjpgs.sh chmod u+x cpjpgs.sh echo "Create ODP fixup script" echo "for f in *odp ; do" > fixodp.sh echo "unzip -p \"\$f\" content.xml > raw.xml" >> fixodp.sh
echo "sed 's/..\/..\/..\/..\/bulkdata\/Cameras\/MCWN/\.\.\/Pictures/g' raw.xml > content.xml"  >> fixodp.sh
echo "zip \"\$f\" content.xml" >> fixodp.sh echo "done" >> fixodp.sh echo "rm raw.xml content.xml" >> fixodp.sh chmod u+x fixodp.sh Run mkdirs.sh, cpjpgs.sh, and fixodp.sh: then it Just Works. Some of the tricky parts: The content.xml file may be stored in unformatted mode, with everything mushed together into one huge line. To make it readable and parse-able, insert a newline between each pair of adjoining angle brackets: sed 's/></>\n</g' This burst of line noise un-escapes the file name from the way LO stores it internally. Note that the middle sed command really does have the literal escape sequence ampersand-amp-semicolon in it and the ampersand in the last one is the sed-ism for “the whole matching string”: sed 's/%20/ /g' | sed 's/&/\&/g' | sed 's/^.*/\"&\"/' The difference between these two sed strings indicates the actual relative path to the Pictures subdirectory in the filesystem and the faked relative path from the LO pseudo-subdirectory where the document stores its internal state. The string of periods in the second command shows what LO stored for the original files in our documents; your mileage will certainly differ: sed 's/\/mnt\/bulkdata\/Cameras\/MCWN/\.\/Pictures/' source.lst > target.lst sed 's/..\/..\/..\/..\/bulkdata\/Cameras\/MCWN/\.\.\/Pictures/' raw.xml > content.xml I don’t know how they could make the file linkages work better, but it’d be really nice if there were a less horrible way to fix the breakage. 1. #1 by madbodger on 2013-02-08 - 08:16 Yeah, it’s hacky, but it does the job and lets you get on with your day. Because I apparently have some odd form of brain damage, I would have used XSLT to tweak the XML. And multiple escaping in XSLT is a truly ugly beast. • #2 by Ed on 2013-02-08 - 10:29 lets you get on with your day That happened after the steam stopped coming out of my ears… • #3 by Red County Pete on 2013-02-08 - 11:12 after the steam I got that in my project to turn the old Sony Vaio back into a Linux box. I went to uninstall Microsoft Works and the install wizard wouldn’t let me do it until I found and inserted the CD. Really, Microsoft? You expect no one to uninstall your low end programs? I hate bugs, and lazy software testers… (Giving them the benefit of the doubt. Failing that, #sendinthedrones) Good luck with the storm. We’re getting a little cold snap, +7 F now, -3 F for tomorrow morning. Whee. • #4 by Ed on 2013-02-08 - 11:19 until I found and inserted the CD How very nineties! The fireproof safe in the garage has all our program distribution CDs, although I have my doubts about how many will be readable in the (decreasingly likely) event that I need them. At one point I’d ripped the CDs to ISO images on a big hard drive, but haven’t kept up with that. In fact, I recently discovered that I’m most of the way through the last spindle of the 700-odd blank CDs I’d bought back in the day. Don’t know if I should buy more, having just picked up a bunch of 4 GB USB drives for booting Linux distros and suchlike… • #5 by Frans on 2013-02-14 - 16:54 Yet Microsoft Works 2 and 3 were actually quite good. • #6 by Ed on 2013-02-14 - 18:33 If you didn’t mind having your documents trapped in a format that no other program could import… [sigh] Been there, done that, won’t get fooled again. • #7 by Frans on 2013-02-15 - 04:09 That’s true. If I can I only use ODT, HTML, and Latex — the latter of which I’m only experimenting with, but it’s looking pretty good. In Debian and derivatives what you need are texlive and an editor, like Texmaker. You can also export from ODT — or anything else Writer imports — to reasonably clean LaTeX, provided you choose a clean option. You can export from LaTeX to pretty decent HTML with hevea. And in turn you can do a decent import in Writer from that generated HTML, which works better than the straight LaTeX to ODT options I tried. • #8 by Ed on 2013-02-15 - 07:21 Latex … I’m only experimenting with, but it’s looking pretty good I highly recommend LyX as a quasi-WYSIWYG front end for LaTeX, which is what I’ve been using to produce the Trinity robot contest rules. Trying to do large documents with a word process will drive you (well, me) mad, but Lyx Just Works: the same document produces PDF (in both Letter and A4) and the HTML version for the website. Well, mostly it Just Works. There’s a lot of software stacked up between the source and PDF, so when the process falls off the rails the error messages don’t really help much at all. • #9 by Frans on 2013-02-15 - 04:16 Oh, and I suppose I should add: for printing HTML I use Prince. In fact I did a little experiment last year of adding some extra CSS to a Gutenberg book from the 1860s and within a couple dozen minutes I ended up with a fantastic looking little book, although for some reason I never did let Lulu print it. • #10 by Frans on 2013-02-15 - 09:17 Yep, that’s exactly why I’m experimenting with LaTeX. I don’t like working with Writer terribly much, although I definitely like it better than MS Word, which secretly invents new styles while you’re not looking and never manages to number tables and illustrations right without the paying the utmost attention — I might as well update the numbers myself if I have to right-click > update everything. I once even wrote a Visual Basic script to “manually” update all such automatic references, but I’ve since lost it. I looked at Lyx, but I was a bit disappointed to find that it used its own format rather than being a more straightforward LaTeX frontend, so I figured I might as well skip the effort of learning Lyx by going straight to e.g. Texmaker or Kile. I basically hoped its WYSIWYM mechanism would work much the same way as a good HTML editor. However, at least for now I find it more distracting than authoring straight HTML, so I might be giving Lyx another chance yet. Also I actually ran into a kind of LaTeX disappointment surprisingly quickly: % See http://en.wikibooks.org/wiki/LaTeX/Tables#Text_wrapping_in_tables \begin{tabular}{| p{0.5\textwidth} | p{0.5\textwidth} |} \hline Jaren ‘60 & Jaren ‘70\\\hline Welvaart, consumptie en vrije tijd & Crisis van de westerse verzorgingstaat en economische crisis\\\hline Bruisende jaren (alles was in beweging) & Matte jaren (stagnatie, uitzichtloosheid)\\\hline Geloof in de vooruitgang & Jaren van het conservatisme\\\hline Dominantie van links = Morele regels staan centraal\\\hline Idealisme en bevlogenheid = politieke Yippie & Pragmatisme = Yuppie (Young urban professional)\\\hline Engagement & Groot individualisme\\\hline Maatschappelijk werk staat centraal & Maatschappelijke desinteresse = Subject en mens staan centraal\\\hline \end{tabular} I had to figure out something seemingly fairly advanced to do something seemingly very basic. That’s not what I had in mind when people were telling me you could just write what you mean and let LaTeX worry about the looks. It looks like customizing styles may be significantly more complicated than CSS, so I’m not quite sure what I think of that yet. But like I said, the fact that I get easy export to decent-enough HTML through hevea, latex2html or eLyXer (thanks for that last one!), it’s very safe for me to experiment. • #11 by Ed on 2013-02-15 - 10:22 just write what you mean and let LaTeX worry about the looks. I had a lot of trouble letting go of the looks. You pick a template and that’s what your text will become: Lyx / LaTeX takes control and that’s just the way it is. If you can’t find a suitable template, then it’s just the wrong hammer for the job, because the amount of manual fiddling will drive you crazy. Forcing produce a particular look seems fraught with peril, although I have used packages to handle things like wrapping long URLs. I made a few feeble attempts to conjure up a package, but quickly realized that I simply don’t want to learn enough to do that. Or, perhaps, that I can’t learn enough to do that. [wince] Of course, stacking up a dozen packages makes the error messages even more impenetrable… • #12 by Frans on 2013-02-15 - 13:21 I understand it should be marginally easier to change certain aspects of the looks by using plain LaTeX than by using LyX. The thing is I also want to move up to experimenting with BibTex references, which should actually simplify certain things a lot, but there’ll be style guides to be obeyed. • #13 by Ed on 2013-02-15 - 16:17 Dunno if this sways your decision or not, but you can apparently use BibTex in LyX right out of the box. Also: “Finally, LyX now also has a wrap table float.” That’s from What’s New for 1.6, which is quite out of date; Ubuntu 12.10 has 2.0.3. • #14 by Frans on 2013-02-16 - 05:02 LyX now also has a wrap table float Good to hear. It doesn’t really matter since this was kind of one of those one-time learning experiences. Or perhaps rather one of those things I now know where to find if I run into them — I doubt I’ll remember the syntax precisely for now. However, it was completely counter to the things people had been saying. In HTML/Prince the same table would’ve been perfectly fine without any column-size settings. Now I’ll admit that in Prince obtaining quite as nice a document would require me to write some CSS and perhaps some JS, but I can do that really, really quickly and besides I can copy over past work. I think Prince also has proper kerning support and the like (better than LO Writer as far as I can tell), but I don’t think it organizes line breaking quite as efficiently, although I’d have to do some tests. In any case I’m baffled at just how bad Writer and Word are at actually making text look good on paper. • #15 by Ed on 2013-02-16 - 07:23 require me to write some CSS and perhaps some JS See, that’s the sort of craziness that leads directly downslope, ending with hand-coded Postscript: when you care enough to position every character. [grin] Using Adobe Framemaker to lay out my book burned out most of my craziness. For the Trinity rules, I admit to adding a few specialized packages to control things like URLs, but the result looks pretty much like what the standard layout prescribes… soooo, the rules look exactly like a LaTeX book. Of course, Knuth wrote TeX specifically to solve his page layout problem, so you’re part of a long tradition: folks who can’t stand ugly page layout and are crazy enough to do something about it! • #16 by Frans on 2013-02-16 - 07:58 See, that’s the sort of craziness that leads directly downslope, ending with hand-coded Postscript: when you care enough to position every character. [grin] No no, I just mean that e.g. headings in HTML don’t do automatic numbering without generated content and indexes don’t generate themselves without some simple Javascript. It is in fact also possible to implement LaTeX-like line-breaking through some JS, but I’m not sure if Prince supports advanced-enough Javascript for that. But perhaps it already does it by itself. I really should run some tests sometime. Of course, Knuth wrote TeX specifically to solve his page layout problem, so you’re part of a long tradition: folks who can’t stand ugly page layout and are crazy enough to do something about it! You’d just think that something like Microsoft Word would typeset beautifully, but instead it’s no better or perhaps even worse than what I got from Microsoft Works 3.0 back in the ’90s. It’s surprisingly similar to the situation with audio players: most don’t do it very well at all! • #17 by Frans on 2013-02-16 - 08:24 I’ll give you some examples. HTML (straight from Gutenberg with only some minor CSS tweaks for nice Prince output — you can see how simpe it all is) PDF (margins are kind of awful because more pages cost more money, hehe. Easy-peasy to play around with, of course) So if the HTML is semi-decent, which includes the output from certain LaTeX to HTML converters, I can get Prince to output a nice-looking PDF in minutes. However, LaTeX is a bit smarter in certain aspects (not tables!), plus it comes with the whole BibTex stuff. Unfortunately styling is nowhere near as easy to tweak as CSS. • #18 by Ed on 2013-02-16 - 09:14 Wow, when that guy got rolling he just couldn’t shut off a paragraph. Page 18 of the PDF presents the biggest wall of text I’ve seen in a while; even adding a bit of space between paragraphs wouldn’t salvage that one! Looks better than my simpleminded Gutenberg books. No argument about that… [wince] • #19 by Frans on 2013-02-16 - 09:41 Oh, I’ll have to take a picture of the book I’m reading right now. It’s inspired by Joyce, so it’s just a gigantic stream of consciousness. It switches around between place and time constantly, much like The Sound And The Fury, but without the helpful italics. *grins* Anyway, the really nice thing is that while it probably took me about half an hour to fix those styles up quite the way I wanted them, now the style and script can be transplanted in any Gutenberg HTML and presumably result in a proper PDF within minutes. Thus any classic is ready for Lulu reprint at roughly$10+shipping almost instantly. Except like I said, I haven’t actually tested Lulu yet.

• #20 by Frans on 2013-02-16 - 10:44

Alright, here’s some information about the book and here’s a picture. It basically goes on for that the entire book, except where there’s dialog. The scribblings could be 40 years old and on this very page I found out they might’ve been have been made by a foreigner.

The annoying past reader of the book* occasionally marked when it switches from one time and place to another (sensible), but also seems to have a strange fascination with references to religion and seemingly completely random things. But on page 65 the word “zweep” (whip) is marked and they wrote “whip” in the margin. So presumably the completely random markings were words they didn’t know.

* Come on, scribble in your own books. Leave the poor library books alone!

• #21 by Frans on 2013-02-16 - 17:54

As an update, due to the conversation here I decided to figure out BibTeX today. Apparently BibLaTeX is a better alternative, so after getting BibTeX to work I went with that instead. I actually only found out about BibLaTeX after searching if there perhaps was some package that provided commands like \citetitle. Unfortunately these nice bibliographic systems seem to break the HTML converters — even the comparatively primitive BibTeX does.

Also, the biblatex and biber packages are not installed yet by the texlive metapackage in Debian and Ubuntu. In Debian Squeeze biber isn’t even packaged.

I think I’ve got most of basics figured out now.

2. #22 by Frans on 2013-02-15 - 09:19

I basically hoped its WYSIWYM mechanism would work much the same way as a good HTML editor.

Whoops, my thoughts became a bit muddled there. I meant I hoped Lyx was to LaTeX as a WYSIWYM HTML editor is to HTML.


text:
## 03 January, 2016

### Record prediction: an absurdity

In a previous post of mine I discussed the inadequacy of the logistic extrapolation for the prediction of the record evolution in athletics. I concluded that post saying that I did not believe that the logistic approximation was to blame. Thus I decided to perform the analysis of the data used in the aforementioned post using different mathematical expressions.

The first expression I am going to analyse here is the four-parameter logistic which has the form
$$L=A+{B\over 1+\exp({b-t\over c})}$$
where L is the length of the throw, t is the time and A,B,b,c are parameters. The standard, three-parameter, logistic expression corresponds to A=0, so adding this term brings an extra freedom which might improve the situation. The figure below shows the best fit of a four-parameter logistic expression to the data. Indeed a small improvement with respect to the extrapolation of the three-parameter logistic used in the previous post is obtained. While previously we found a prediction for the 2015 record of circa 83 m, with the four-parameter expression we obtain a prediction of 81 m, still way off.

Next I turn to another expression widely used in various domains of biology or finance, the Gompertz law. While the logistic expression is a symmetrical sigmoïd, the Gompertz function has a rapid initial growth and a slower approach to the final asymptote. The precise expression of the Gompertz law is
$$L=A+B\exp\left({-\exp({b-t\over c})}\right)$$
again a four parameter function. It turns out that the Gompertz law leads to a much stiffer fit and an extrapolation of the record for 2015 beyond 85 m.

What is the conclusion one can draw from this analysis? To sum it up in a catchy way: "garbage in, garbage out". It is not the mathematical tool used for the analysis that is at fault. It is the fact that we are attempting an analysis based on the past trend that is to blame. No prediction can be made unless one takes into account the reality of the discipline. In the case of women's discus the fact that the record did stagnate, with the best performances of the past decade several meters behind those of the late 80s, should essentially be attributed to the better antidoping controls introduced in the 90s. Thus it is not the mathematical analysis that is inadequate but its use with inappropriate data.

At this point I cannot resist the temptation to make a remark, based on the analysis presented in an article, co-authored with Y. Charon, and published in New Studies in Athletics  29:4 (2014) page 37. The world record, despite its absolute and gripping character, should not be used in order to assess the progression of a discipline. In the figure below we show the progression of the 50th performer for women's triple jump since 1992 (shortly after the IAAF recognised officially this event) till 2012. While the world record has remained unbeaten since 1995, the performance of the 50th performer is increasing steadily, representing faithfully the progress of the discipline.

Given the smooth progression one would be tempted to use the data on the 50th performer and extrapolate towards the future. The dashed line in the figure does just that using a three-parameter logistic formula. And, once more we obtain an absurd result. The asymptotic value we find is a mere 14.73 m, a performance I am convinced will be reached (and surpassed) by the 50th performer before the end of the decade.

The whole point of this post is that record prediction is a very subtle business and no mathematical approach will ever work even for short-term predictions. The situation is slightly better if one considers the performances not at the very top (like the first 5) of the discipline but rather those of the elite (say the 50th performer) provided one limits oneself to really short-term predictions. But this is something any competent coach can do without using any mathematics.

format: plain


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# 22.11 More applications of magnetism  (Page 3/12)

 Page 3 / 12

An image requires position information as well as the density of a nuclear type (usually protons). By varying the magnetic field slightly over the volume to be imaged, the resonant frequency of the protons is made to vary with position. Broadcast radio frequencies are swept over an appropriate range and nuclei absorb and reemit them only if the nuclei are in a magnetic field with the correct strength. The imaging receiver gathers information through the body almost point by point, building up a tissue map. The reception of reemitted radio waves as a function of frequency thus gives position information. These “slices” or cross sections through the body are only several mm thick. The intensity of the reemitted radio waves is proportional to the concentration of the nuclear type being flipped, as well as information on the chemical environment in that area of the body. Various techniques are available for enhancing contrast in images and for obtaining more information. Scans called T1, T2, or proton density scans rely on different relaxation mechanisms of nuclei. Relaxation refers to the time it takes for the protons to return to equilibrium after the external field is turned off. This time depends upon tissue type and status (such as inflammation).

While MRI images are superior to x rays for certain types of tissue and have none of the hazards of x rays, they do not completely supplant x-ray images. MRI is less effective than x rays for detecting breaks in bone, for example, and in imaging breast tissue, so the two diagnostic tools complement each other. MRI images are also expensive compared to simple x-ray images and tend to be used most often where they supply information not readily obtained from x rays. Another disadvantage of MRI is that the patient is totally enclosed with detectors close to the body for about 30 minutes or more, leading to claustrophobia. It is also difficult for the obese patient to be in the magnet tunnel. New “open-MRI” machines are now available in which the magnet does not completely surround the patient.

Over the last decade, the development of much faster scans, called “functional MRI” (fMRI), has allowed us to map the functioning of various regions in the brain responsible for thought and motor control. This technique measures the change in blood flow for activities (thought, experiences, action) in the brain. The nerve cells increase their consumption of oxygen when active. Blood hemoglobin releases oxygen to active nerve cells and has somewhat different magnetic properties when oxygenated than when deoxygenated. With MRI, we can measure this and detect a blood oxygen-dependent signal. Most of the brain scans today use fMRI.

## Other medical uses of magnetic fields

Currents in nerve cells and the heart create magnetic fields like any other currents. These can be measured but with some difficulty since their strengths are about ${\text{10}}^{-6}$ to ${\text{10}}^{-8}$ less than the Earth’s magnetic field. Recording of the heart’s magnetic field as it beats is called a magnetocardiogram (MCG)    , while measurements of the brain’s magnetic field is called a magnetoencephalogram (MEG)    . Both give information that differs from that obtained by measuring the electric fields of these organs (ECGs and EEGs), but they are not yet of sufficient importance to make these difficult measurements common.

what is nuclear reaction?
In a chemical reaction, you have atoms being rearranged in different patterns, so you end up with the same atoms but different molecules. In a nuclear reaction, you go one step deeper: you rearrange protons and neutrons, do you end up with different atoms.
So, for example, stars fuse 2 Hydrogen atoms into 1 Helium atom (that's called nuclear fusion). Nuclear reactors break down heavy unstable atoms into smaller ones (that's nuclear fission)
whats drag force?
who can explain me about the connecting between energy and work? I don't understand about the equation of the formula
Energy can be defined as the ability an object has to do work. so lets say if u want to move something from one place to another you would need energy to do it. a table a certain distance, but if u dont have energy that means you will not be able to move it. Work=Force×distance.
Mario
from work-kinetic energy theorem we get that work=change in kinetic energy
Mario
what is thermo electric thermometer
Who can help me with dynamics?
can someone enumerate the First and second law of thermodynamics
radiation of phones kept amazing me
f=m(v-u)/t
why acceleration due to gravity varies from place to place
I understand light is a range of wavelenghts from em spectrum, but Where do photons come from in particular, how it is emitted from the sun?
please what is the formula for calculating Newton second law of motion?
F=ma
pierre
what is emotion
properties of transverse waves
is visible light electromagnetic wave?
Visible light is a range of wavelengths within the electro magnetic spectrum.
Robert
It is electro magnetic radiation from the sun.
Robert
please what is the formula for coefficient of kinetic friction
What is work


text:
experiment on extraction of copper

• Extracting metals with charcoal Resource RSC Education

This extraction experiment consists of two competition reactions. A metal oxide is reacted with charcoal. If the charcoal (carbon) is more reactive it will remove the oxygen from the metal oxide and leave a trace of metal in the reaction vessel. Start with an oxide of lead, then observe what happens to an oxide of copper.

• The Extraction of Copper Chemistry LibreTexts

Extracting of Copper from Other Ores. Copper can be extracted from non-sulfide ores by a different process involving three separate stages: Reaction of the ore (over quite a long time and on a huge scale) with a dilute acid such as dilute sulfuric acid to produce a very dilute copper(II) sulfate solution.

• Copper Extraction Experiment Aurania Resources

Seeing is Believing for Ecuador’s Vice-Minister of Mines. This experiment, designed to illustrate the simplicity of copper extraction from sedimentary-hosted mineralization, was recorded at Aurania’s Ecuadorean field office during a visit from Ecuador’s Vice-Minister of Mines, Fernando L. Benalcazar.

• Copper extraction Wikipedia

Copper extraction refers to the methods used to obtain copper from its ores. The conversion of copper consists of a series of physical and electrochemical processes. Methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors.

• Extracting Metal with Charcoal STEM

In this classic experiment, from the Royal Society of Chemistry, students extract metals from their metal oxides using carbon. By strongly heating a mixture of copper oxide and charcoal students will observe small amounts of copper metals produced in the mixture when cooled. The resource is set out as teachers' notes followed by the students' page which presents the task to be investigated.

• Copper Extraction Demonstration Examples

The copper extraction demonstration takes about 10 minutes of class time. It is helpful to follow the demonstration with a brief discussion of what happened, which might take as long as 20 minutes. The discussion allows time for copper to precipitate onto a nail at the end of the demonstration. This precipitate can be passed around either

• The Chemistry of Copper Electrolysis Superfund

3. Copper wire is used because copper is known for its properties as an excellent electrical conductor (it likely does not contribute significantly to the plating of copper on the dime). 4. The longer the experiment is run, the more copper plating will appear on the dime. 5. One would have to know what the content of each coin is modern

• Experiment: Preparation of Copper Sulfate from Copper

Detailed revision notes on the topic Experiment: Preparation of Copper Sulfate from Copper Oxide. Written by teachers for the Edexcel IGCSE Chemistry course.

• Carbon reduction of Copper Oxide YouTube

Jan 28, 2015· Micro scale reduction of Copper Oxide

• Author: CLEAPSS
• LIQUID-LIQUID COPPER EXTRACTION PROCESS

This experiment involves the extraction of copper from an aqueous copper sulfate solution using a solution of LIX (a copper complexing agent) in kerosine. Runs will be made at different feed and stirring rates, in some cases under conditions in which the streams leaving the mixer-settler are in equilibrium. In other cases equilibrium will not

• Acid Leaching Copper Ore Treatment Method

PREPARATION OF THE COPPER ORE. This study is limited in general to percolation leaching as it is the most widely used method to give proper contact of solvent with the ore to effect extraction of the copper. One of the important factors in percolation leaching is the size reduction necessary for copper recovery within reasonable time limits.

• Extraction of Copper QS Study

Extraction of Copper. Copper pyrites is the main ore. The method used to extract copper from its ores depends on the nature of the ore. Sulphide ores such as chalcopyrite are converted to copper by a different method from silicate, carbonate or sulphate ores.

• copper extraction and purification

Extracting copper from other ores. Copper can be extracted from non-sulphide ores by a different process involving three separate stages: Reaction of the ore (over quite a long time and on a huge scale) with a dilute acid such as dilute sulphuric acid to produce a very dilute copper(II) sulphate solution.

• Extraction of copper from copper oxide experiment

Extraction of copper from copper oxide Extraction. In experiment C1511, charcoal is the reducing agent to reduce tenorite CuO to elementary copper When heated, the mixture of tenorite and pulverised charcoal produces red copper and carbon dioxide A saturated calcium hydroxide solution is used to v.

• Solvent Extraction of Copper experiment Oresome

In this experiment students carry out an investigation similar to what is conducted within industrial laboratories. Information and directions are provided for the experiment which investigates the recovery of copper metal from ore using solvent extraction.

• Copper Lab AP Chemistry Lab Reports

After sulfuric acid was added to the beaker, copper was found as copper ions with a 2+ charge instead of the previous copper(ii) oxide form. 6. In the final step of the lab when the copper precipitate was washed, zinc ions were removed. The previous reaction that took place involved aqueous copper(ii) sulfate and solid zinc.

• Copper recovery using leach/solvent extraction

Copper recovery using leach/solvent extraction/electrowinning technology 65 (Figure 2) and a catalytic amount of LIX 63, was introduced in 19657 and in March 1968 the first commercial copper L/SX/EW operation, the Bluebird plan of Ranchers

• Copper extraction by wet chemical method ScienceDirect

In this experiment, the percentage of copper extracted using in situ extraction and the reduction method was low. The fact that some of the hydrazones acted as a ligand to extract the copper from ore into solution to make it available for reduction contributed to this fact.

• Chemistry of Copper Chemistry LibreTexts

The important ores of copper are copper pyrites ($$CuFeS_2$$), cuprite and copper glance. The copper ores are mostly found in the north of India. The extraction of copper also involves many steps. The ore used for extraction is copper pyrites, which is crushed,

• Experiment: Reduction of copper using carbon Free ZIMSEC

At the beginning of the experiment the copper oxide was black; The copper oxide is reduced during the experiment and it the mixture turns to copper-red/brown; The reaction is shown using the equation: \text{copper oxide+carbon}\rightarrow\text{copper+carbon dioxide} Conclusion. Copper oxide can be reduced to copper using carbon

• SOLVENT EXTRACTION IN HYDROMETALLURGICAL

diluents used for copper(II) extraction is their low extraction capacity (maximum copper concentration to obtain in loaded organic phase), which reaches from 6 to 8 g Cu(II)/dm3 (Szymanowski, 1990). According to Eq. 1, the extraction reaction of metal cations is reversible towards hydrogen ions. Equilibrium state of the reaction (Eq. 1) is

• Copper extraction by wet chemical method ScienceDirect

In this experiment, the percentage of copper extracted using in situ extraction and the reduction method was low. The fact that some of the hydrazones acted as a ligand to extract the copper from ore into solution to make it available for reduction contributed to this fact.

• PSP Report Analysis of Copper Ion extraction from water

analysis of copper ion extraction from water using coffee grounds hassan abdullah 12577918 janet mackie 12574974, ali atoui 12577920, mathew holt 12614259. Sign in Register; Hide. PSP Report Analysis of Copper Ion extraction from water using coffee grounds.

• GCSE CHEMISTRY Extraction of Copper Thermal

to extract copper from low grade ores (see below). The traditional method of extraction is to heat the copper sulfide. Copper(II) sulfide gives copper and sulfur dioxide during thermal decomposition. Thermal decomposition means that the compound breaks down into other substances when it is heated. Thermal decomposition is an endothermic reaction.

• SOLVENT EXTRACTION IN HYDROMETALLURGICAL

diluents used for copper(II) extraction is their low extraction capacity (maximum copper concentration to obtain in loaded organic phase), which reaches from 6 to 8 g Cu(II)/dm3 (Szymanowski, 1990). According to Eq. 1, the extraction reaction of metal cations is reversible towards hydrogen ions. Equilibrium state of the reaction (Eq. 1) is

• Purifying copper by electrolysis Electrolysis GCSE

Copper is purified by electrolysis. Electricity is passed through solutions containing copper compounds, such as copper(II) sulfate. The anode (positive electrode) is made from impure copper and

• Copper History: Copper through the Ages

Copper has been an essential material to man since pre-historic times. In fact, one of the major "ages" or stages of human history is named for a copper alloy, bronze. Copper and it's many alloys have played an important role in many civilizations, from the ancient Egyptians, Romans to modern day cultures around the world. Here, you will find a number of reference materials detailing the role

• chemistry of copper lab 28 Flashcards Quizlet

A 0.0194-g sample of copper metal is recycled through the series of reactions in this experiment. If 0.0169g of copper is the recovered after the series of reactions in this experiment, what is the percent recovery of the copper metal?

• Nuffield practical collection RSC Education

This extraction experiment consists of two competition reactions. A metal oxide is reacted with charcoal. If the charcoal (carbon) is more reactive it will remove the oxygen from the metal oxide and leave a trace of metal in the reaction vessel. Start with an oxide of lead, then observe what happens to an oxide of copper.

• Innovations: Introduction to Copper: Mining & Extraction

Modern methods of extraction allow economic leaching and electro-winning of copper from low-grade ores and extraction techniques are continuously being refined and developed to achieve the most efficient removal of copper from a wide variety of ores from sources around the globe.

• Practical activity Electrolysis OCR Gateway GCSE

to completely fill two small test tubes with copper(II) sulfate solution. Quickly turn each test tube upside down, keeping its mouth under the surface of the copper(II) sulfate solution.

• Copper Mining and Processing: Processing of Copper Ores

Copper processing is a complicated process that begins with mining of the ore (less than 1% copper) and ends with sheets of 99.99% pure copper called cathodes, which will ultimately be made into products for everyday use.The most common types of ore, copper oxide and copper sulfide, undergo two different processes, hydrometallurgy and pyrometallurgy, respectively, due to the different

• Lab Report on copper cycle SlideShare

Oct 29, 2013· Lab Report on copper cycle 1. Purpose: The purpose of this experiment is to demonstrate a cycle of reactions involving copper. A specific quantity of copper will be transformed through a series of reactions and then recovered as solid copper. A percent recovery will be calculated and sources of loss (or gain) will be identified.

• AN INTRODUCTION TO COPPER EXTRACTION

The copper extraction process begins at an open cut mine where Copper Ore is blasted and removed via Excavators and Tip Trucks. The ore is fed to a Crusher where it is broken down to a specified maximum size and passed through to a conveyor. When the crushed ore falls onto the AN INTRODUCTION TO COPPER EXTRACTION

• Chemical Reactions of Copper and Percent Yield

Most chemical syntheses involve separation and purification of the desired product from unwanted side products. Common methods of separation include filtration, sedimentation, extraction, decantation, and sublimation. This experiment will use chemical reactions to separate copper from copper compounds.


text:
# Is it possible to have high compression but low predictability?

Can you have a process that generates a binary sequence with high compression rate (low entropy) but impossible to predict next symbol?

'impossible to predict' - sequence cannot be predicted theoretically. But I was also asking about the real life example (no polynomial algorithm).

• Please formally define "impossible to predict". As you can see, your unclear definition results in two totally different answers. orip's answer assumes there is (possibly) no polynomial algorithm that can predict the sequence, while D.W.'s answer assumes the sequence cannot be predicted theoretically. – xskxzr Sep 14 at 3:42

No. Let $$x_1,x_2,\dots,x_n$$ be the bits of the binary sequence.

Suppose $$\Pr[x_{i+1} | x_1,\dots,x_i] = 1/2$$ for all $$i$$. Then it is impossible to predict the next bit; however, it is also easy to see that $$x_1,\dots,x_n$$ is uniformly distributed on $$\{0,1\}^n$$, so has entropy $$n$$ (high entropy; no compression possible).

Alternatively, suppose $$\Pr[x_{i+1} | x_1,\dots,x_i] \ne 1/2$$ for some $$i$$. Then it is possible to predict the next bit better than chance.

Those are the only two possible cases. In every case, either the next bit is predictable, or you can't compress.

This assumes you are talking about what is possible with infinite computing power (which isn't realistic, but is what is typically assumed in information theory).

Yes. A cryptographic stream cipher can generate an incredibly long string (e.g. ChaCha20 can generate $$256 \times 2^{128}$$ bits) from a single small key (e.g. 256 bits).

If you do not know the key that was used this stream is impossible to predict.

• will it be highly compressible? I mean low entropy. – Oleg Dats Sep 12 at 9:50
• @OlegDats Yes, the entropy is still just 256 bits - you can generate everything from just the key. – orlp Sep 12 at 10:14
• 256 bits + lenght of the code of ChaCha20 algorithm? – Oleg Dats Sep 12 at 10:26
• @OlegDats That depends on your definition of entropy, but in traditional Kolmogorov complexity that would be an upper bound for any implementation of ChaCha20, yes. It is unknown what the smallest size implementation of ChaCha20 is though. In cryptography we go by Kerckhoffs's principle and only count the bits of the secret key as our entropy. – orlp Sep 12 at 10:29
• @gnasher729 ChaCha20 is not invertible, so the first 256 bits of output probably does not give enough information even in the ideal case. And how do you define 'possible to predict'? If your prediction takes longer than the heat death of the universe, is that 'possible'? – orlp Sep 13 at 10:44

The accepted answer is plainly wrong.

It's not really low predictability. After the first 256 bits, the rest is perfectly predictable, it is just very hard. It's not impossible to predict. So the answer is wrong.

And the argument doesn't make sense. It's very hard to predict (but not impossible) without knowing the key. But it is equally very hard (but not impossible) to compress without knowing the key.

• Maybe you are right, it is impossible to compress without knowing the key. (I will de accept the current answer) – Oleg Dats Sep 13 at 7:47
• This does not answer the question. It is better to be a long comment. – xskxzr Sep 14 at 3:38


text:
Receiver sensitivity is defined as the minimum signal power (Pi,min) at which a receiver can detect a signal while providing an adequate SNR at analog receiver output (BER at digital receiver output).

This is minimum detectable signal(MDS) power. In a multi-standard receiver, the sensitivity requirements vary depending on mode of operation, band, bandwidth, etc.,
For example,

1. GSM standard requires a minimum sensitivity of -102dBm
2. LTE Band-2 minimum sensitivity requirements: -102.7dBm for 1.4MHz bandwidth mode, and -92dBm for 20MHz bandwidth mode. Sensitivity requirements vary in LTE from band-to-band and across bandwidth modes.

In this post, let us go through the receiver sensitivity calculation using kTB, noise figure, and SNR of the receiver. GSM sensitivity and WLAN sensitivity calculations are explained through examples.

The noise figure of a receiver is given by

(1)

where,
– SNR at the input receiver
– SNR at the output of receiver

The minimum SNR required at the output of receiver is obtained from system level design calculations or simulations.

SNR at the input (SNRi) of a receiver is determined by input signal power(Pi) and noise floor(NFloor).

(2)

The noise floor at the input of the receiver is mainly due to thermal noise. Available thermal noise power at temperature and an equivalent noise bandwidth of is given by . The reference temperature of 290K is utilized to calculate noise floor. At , . Therefore noise floor is given by

(3)

where is the bandwidth of receiver in Hz.

Using Eq-(1) to Eq-(3), the noise figure of a receiver is given by

(4)

From Eq-(4), knowing the noise figure and minimum SNR requirement of the receiver, we can calculate the receiver sensitivity as

(5)

From the above equation, we can observe that sensitivity depends on receiver bandwidth, receiver noise figure and SNR(or BER) at the output of receiver. Receiver bandwidth is not same as channel bandwidth. Receiver bandwidth is mainly determined by IF filter or channel selection filter, but trade-off with lot other parameters.

For circuit designers, the design variable noise figure is of interest than the receiver sensitivity. For a communication standard given the receiver sensitivity, Eq-(4) is useful to find the noise figure of receiver. Then using Friss equation, noise figure for each block in the cascaded chain can be distributed.

## Example: Sensitivity of a GSM receiver

Calculate the sensitivity of a GSM receiver whose noise figure is 10dB and minimum SNR at the output of receiver is 10dB.
Assume that input noise power is dominated by thermal noise and the bandwidth of Rx is 200kHz. Then noise floor at the input of receiver is
Then receiver sensitivity is given by

In case of digital receivers, sensitivity is defined as minimum power level at which the receiver demodulate the received data with a specified BER, FER or PER or below that. The maximum BER dictates the minimum output SNR(SNRo,min) necessary for satisfactory reproduction or demodulation of the desired signal.

The relation between SNR and BER at the output of receiver is given as,

(6)

R – Bit rate
B – Channel bandwidth
Eb/No – Energy per bit to noise power spectral density ratio

BER as a function of Eb/No is shown in Figure 1. Given the modulation scheme and BER required, pick the value of Eb/No from Figure 1 and compute the required output SNR using Eq-(6).

Figure 1. Theoretical BER over AWGN for various digital modulation techniques
Image courtesy: Gaussian Waves

## Example: Sensitivity of a WLAN receiver

Calculate the required noise figure of a WLAN receiver to detect a 64QAM signal carrying data at the rate of 54Mbps. Assume the sensitivity of the receiver as -65dBm.

IEEE standard defined the sensitivity of WLAN receiver[1]. In simple words the sensitivity of WLAN 802.11a receiver can be stated as “the minimum signal level at which the receiver detects and demodulate the signal with a PER of 10% or less than that”.

Probability of a packet received correctly()

(7)

where is the probability of a packet received in error.
is the probability that a bit is received in error and is the packet length.

For PER < 10%, , .

From BER versus Eb/No plot shown in Figure 1, for 64QAM signal corresonding to BER of 3×10-5, Eb/No is 17dB.

Each sub-carrier codes 6bits, so 48 subcarriers code 288 bits. The duration of OFDM symbol is 4sec. Therefore

Finally SNR at the output of receiver

(8)

From Eq-(4), we can compute the NF of WLAN receiver as

Table below shows the required minimum sensitivity of a WLAN 802.11a receiver at different data rates[1].

 Data rate (Mbps) 6 9 12 18 24 36 48 54 Rx Sensitivity (dBm) -82 -81 -79 -77 -74 -70 -66 -65

## References

[1] “Receiver minimum input level sensitivity, agilent technologies.” [Online; Accessed June 2014]. Available: http://www.home.agilent.com/agilent/editorial.jspx?ckey=339504&id=339504&nid=-11143.0.00&lc=eng&cc=IN


text:
My Math Forum Set notation with empty set

 Number Theory Number Theory Math Forum

 November 11th, 2017, 05:28 AM #1 Member   Joined: Oct 2017 From: Rumba Posts: 39 Thanks: 0 Set notation with empty set Let A = ∅, B = {7, 8, 9, 1, {∅}}. For each of the following, state whether the statement is True or False. (a) ∅ ∈ A = true (b) A ⊂ B = false (c) P(A) ∈ B = false (d) B ⊆ A = true (e) A ⊆ B = true (f) A ⊆ ∅ = false
November 11th, 2017, 08:48 AM   #2
Senior Member

Joined: Aug 2012

Posts: 2,357
Thanks: 740

Quote:
 Originally Posted by sita Let A = ∅, B = {7, 8, 9, 1, {∅}}. For each of the following, state whether the statement is True or False. (a) ∅ ∈ A = true
No, the empty set is empty. It does not have any elements. This is false.

Quote:
 Originally Posted by sita (b) A ⊂ B = false
No, the empty set is a subset of every set, so this is true.

Quote:
 Originally Posted by sita (c) P(A) ∈ B = false
No. What is $P(A)$? The power set of the empty set is $\{\emptyset\}$, which is an element of B. This is true.

Quote:
 Originally Posted by sita (d) B ⊆ A = true
No, this is false. It is not the case that every element of B is an element of A.

Quote:
 Originally Posted by sita (e) A ⊆ B = true
Yes. The empty set is a subset of every set.

Quote:
 Originally Posted by sita (f) A ⊆ ∅ = false
Yes. Every set is a subset of itself.

Last edited by Maschke; November 11th, 2017 at 08:51 AM.

 November 11th, 2017, 09:00 AM #3 Math Team     Joined: May 2013 From: The Astral plane Posts: 2,257 Thanks: 928 Math Focus: Wibbly wobbly timey-wimey stuff. I don't want to distract from the OP's problem, but I'm curious.... Don't a) and f) contradict each other? If $\displaystyle A \in \emptyset$ because every set is a subset of itself, then why isn't $\displaystyle \emptyset \in A$ by the same argument? -Dan
November 11th, 2017, 09:47 AM   #4
Senior Member

Joined: Aug 2012

Posts: 2,357
Thanks: 740

Quote:
 Originally Posted by topsquark I don't want to distract from the OP's problem, but I'm curious.... Don't a) and f) contradict each other? If $\displaystyle A \in \emptyset$ because every set is a subset of itself, then why isn't $\displaystyle \emptyset \in A$ by the same argument? -Dan
The empty set is empty, so $x \in \emptyset$ is false for every $x$.

But the empty set is a subset of every set, including itself. We say $X \subset Y$ if it is the case that $x \in X \implies x \in Y$. For any set $X$, it's vacuously true that if $x \in \emptyset$ then $x \in X$, because there is no $x$ that's an element of $X$.

In other words the statement $x \in \emptyset \implies x \in X$ is true, because the antecedent is always false. $x \in \emptyset$ is always false, making the implication true. So by definition, $\emptyset \subset X$.

So the empty set contains no elements, but the empty set is a subset of every set.

Last edited by Maschke; November 11th, 2017 at 09:57 AM.

 November 11th, 2017, 05:13 PM #5 Math Team   Joined: Jan 2015 From: Alabama Posts: 3,264 Thanks: 902 The difference between (a) and (f) is the difference between "$\displaystyle \in$" and "$\displaystyle \subset$" Thanks from Maschke and topsquark

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text:
Vector space of polynomials problem

1. Oct 29, 2007

captainjack2000

1. Consider the vector space of polynomials 1+x^3 , 1-x+x^2, 2x, 1+x^2
Are they linearly dependent or independent? dimension of vecotr space spanned by these vectors?

3. I have tried to solve this by letting
a1 = 1+x^3
a2 = 1-x+x^2
a3 = 2x
a4 = 1+x^2

Then I let
(alpha)a1 + (beta)a2 + (gamma)a3 + (delta)a4 = 0
(alpha)(1+x^3) + (beta)(1-x+x^2) + (gamma)(2x) +(delta)(1+x^2) = 0
(alpha +beta+delta) + x(2gamma - beta) + x^2(beta + delta) + x^3(alpha) = 0

So alpha + beta+ delta = 0
2gamma - beta = 0
beta + delta = 0
alpha = 0

But I can't solve for beta delta and gamma so how do I know if their independent or dependent?

2. Oct 29, 2007

Dick

There's no unique solution, so you'll have to write the solution in terms of some of your other variables. In this case it looks easy to solve for the other variables in terms of beta. Then ask yourself if there are any nonzero solutions.

3. Oct 29, 2007

captainjack2000

Vectors!

In that case beta = -delta
and gamma = beta/2
and alpha = 0

How can you tell if they are non-zero?
How do you find the dimension?

4. Oct 29, 2007

Dick

That gives you a solution for every value of beta. So putting beta=1 tells you what about linear independence?


text:
Class 9 Matter, States of matter and evaporation

### Topics to be covered

=> Matter
=> States of matter
=> Can matter change its state?
=> Effect of change of pressure
=> Evaporation

### MATTER

Anything which occupies space and has mass is called matter. For eg:chair,car,table, clouds, stars etc.

color{green}("𝐒𝐎𝐌𝐄 𝐈𝐌𝐏𝐎𝐑𝐓𝐀𝐍𝐓 𝐀𝐂𝐓𝐈𝐕𝐈𝐓𝐈𝐄𝐒")

color{red}("𝐎𝐁𝐒𝐄𝐑𝐕𝐀𝐓𝐈𝐎𝐍")

color{green}(•) Matter is made up of tiny particles.

color{green}(•) There is space between tiny particles.

color{red}("𝐎𝐁𝐒𝐄𝐑𝐕𝐀𝐓𝐈𝐎𝐍")
color{green}(•) Particles of matter are very small.

color{red}("𝐎𝐁𝐒𝐄𝐑𝐕𝐀𝐓𝐈𝐎𝐍")

color{green}(•) Particles of matter are continuously moving, that is, they possess what we call the kinetic energy.

color{green}(•) As the temperature rises, particles move faster. So, we can say that with increase in temperature the kinetic energy of the particles also increases.

color{green}(•) Particles of matter intermix on their own with each other. They do so by getting into the spaces between the particles.

This intermixing of particles of two different types of matter on their own is called color{red}("𝐝𝐢𝐟𝐟𝐮𝐬𝐢𝐨𝐧") and on heating,
diffusion becomes faster.

color{green}("𝐏𝐑𝐎𝐏𝐄𝐑𝐓𝐈𝐄𝐒 𝐎𝐅 𝐌𝐀𝐓𝐓𝐄𝐑")

color{green}(•) Matter is made up of small particles.

color{green}(•) These particles are very small in size.

color{green}(•) These particles are moving constantly( They possess what we call the kinetic energy. As the temperature rises, particles move faster. So, we can say that with increase in temperature the kinetic energy of the particles also increases.)

color{green}(•) These particles have spaces between them.

color{green}(•) Particles of matter attract each other because of force of attraction present between them.

### States of matter

Matter around us exists in three different states– solid, liquid and gas. These states of matter arise due to the variation in the characteristics of the particles of matter.

color{green}("𝐒𝐎𝐋𝐈𝐃:")

color{green}(•) They have fixed volume and shape.

color{green}(•) Particles are closely packed .

color{green}(•) They have less spacing between them.

color{green}(•) They have distinct boundaries.

color{green}(•) They have negligible compressibility.

color{green}(•) They are rigid.

color{green}(•) Example: sugar, stone, wood etc.

color{green}("𝐋𝐈𝐐𝐈𝐔𝐃:")

color{green}(•) They don’t have fixed shape.

color{green}(•) They take the shape of container in which they are kept.

color{green}(•) They have fixed volume.

color{green}(•) They are not rigid.

color{green}(•) They have tendency to flow that’s why they are called fluids.

color{green}(•) Example: milk, water, petrol etc.

color{green}("𝐆𝐀𝐒:")

color{green}(•) They have indefinite shape and volume.

color{green}(•) Particles have very large space between them and weak force of attraction.

color{green}(•) Due to high speed of particles and large space between them, gases show the property of diffusing very fast into other gases.

color{green}(•) They are highly compressible.

color{green}(•) Gases can move randomly due to which the particles hit each other and also the walls of the container. The pressure exerted by the gas is because of this force exerted by gas particles per unit area on the walls of the container.

### Can Matter Change its State?

color{green}(•) As the temperature of the solids is increased, their kinetic energy increases due to which the particles start vibrating with greater speed. The energy supplied by heat overcomes the forces of attraction between the particles. The particles leave their fixed positions and start moving more freely.

color{green}(•) A stage is reached when the solid melts and is converted to a liquid.

color{green}(•) The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its color{red}("𝐦𝐞𝐥𝐭𝐢𝐧𝐠 𝐩𝐨𝐢𝐧𝐭") . The melting point of ice is color{red}("273.16 K*").

color{green}(•) The process of melting, that is, change of solid state into liquid state is also known as fusion.

color{green}("𝐋𝐀𝐓𝐄𝐍𝐓 𝐇𝐄𝐀𝐓 𝐎𝐅 𝐅𝐔𝐒𝐈𝐎𝐍")

During melting, the temperature of the system does not change after the melting point is reached, till all the ice melts. This happens even though we continue to heat the beaker and heat gets used up in changing the state by overcoming the forces of attraction between the particles.

As this heat energy is absorbed by ice without showing any rise in temperature, it is considered that it gets hidden into the contents of the beaker and is known as the color{red}("𝐥𝐚𝐭𝐞𝐧𝐭 𝐡𝐞𝐚𝐭"). The word latent means hidden.

The amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point is known as the color{red}("𝐥𝐚𝐭𝐞𝐧𝐭 𝐡𝐞𝐚𝐭 𝐨𝐟 𝐟𝐮𝐬𝐢𝐨𝐧"). So, particles in water at color{red}(0^0 C (273 K)) have more energy as compared to particles in ice at the same temperature.

color{green}("𝐁𝐎𝐈𝐋𝐈𝐍𝐆 𝐏𝐎𝐈𝐍𝐓")

When we supply heat energy to water, particles start moving even faster. At a certain temperature, a point is reached when the particles have enough energy to break free from the forces of attraction of each other. At this temperature the liquid starts changing into gas.

The temperature at which a liquid starts boiling at the atmospheric pressure is known as its color{red}("𝐛𝐨𝐢𝐥𝐢𝐧𝐠 𝐩𝐨𝐢𝐧𝐭.") Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain enough energy to change into the vapour state. For water this temperature is color{red}(373 K (100^0C = 273 + 100 = 373 K)). Particles in steam, that is, water vapour at color{red}(373 K (100^0 C)) have more energy than water at the same temperature. This is because particles in steam have absorbed extra energy in the form of latent heat of vaporisation.

Substances around us change state from solid to liquid and from liquid to gas on application of heat. But there are some that change directly from solid state to gaseous state and vice versa without changing into the liquid state.

A change of state directly from solid to gas without changing into liquid state (or vice versa) is called color{red}("𝐬𝐮𝐛𝐥𝐢𝐦𝐚𝐭𝐢𝐨𝐧.")

color{red}("Solid State" underset("Cool") overset("Heat")⇄ " Liquid State" underset("Cool") overset(" Heat") ⇄ " Gaseous State")

### EFFECT OF CHANGE OF PRESSURE

When the pressure over the piston is applied the gas present inside the container starts compressing and the particles start coming close to each other. Now when the pressure is applied and temperature is reduced the gases start to liquify.

Solid carbon dioxide color{red}((CO_2)) is stored under high pressure. It gets converted directly to gaseous state on decrease of pressure to 1 atmosphere* without coming into liquid state. This is the reason that solid carbon dioxide is also known as dry ice.

𝐓𝐡𝐮𝐬, 𝐰𝐞 𝐜𝐚𝐧 𝐬𝐚𝐲 𝐭𝐡𝐚𝐭 𝐩𝐫𝐞𝐬𝐬𝐮𝐫𝐞 𝐚𝐧𝐝 𝐭𝐞𝐦𝐩𝐞𝐫𝐚𝐭𝐮𝐫𝐞 𝐝𝐞𝐭𝐞𝐫𝐦𝐢𝐧𝐞 𝐭𝐡𝐞 𝐬𝐭𝐚𝐭𝐞 𝐨𝐟 𝐚 𝐬𝐮𝐛𝐬𝐭𝐚𝐧𝐜𝐞, 𝐰𝐡𝐞𝐭𝐡𝐞𝐫 𝐢𝐭 𝐰𝐢𝐥𝐥 𝐛𝐞 𝐬𝐨𝐥𝐢𝐝, 𝐥𝐢𝐪𝐮𝐢𝐝 𝐨𝐫 𝐠𝐚𝐬.

### EVAPORATION

V
color{green}(•) The process of conversion of liquid to gas due to escaping of particles from liquid surface is called evaporation.

color{green}(•) It takes place only at the surface of liquid.

color{green}(•) It can take place at room temperature also.

color{green}("𝐅𝐀𝐂𝐓𝐎𝐑𝐒 𝐀𝐅𝐅𝐄𝐂𝐓𝐈𝐍𝐆 𝐑𝐀𝐓𝐄 𝐎𝐅 𝐄𝐕𝐀𝐏𝐎𝐑𝐀𝐓𝐈𝐎𝐍:")

color{red}("𝟏 𝐒𝐔𝐑𝐅𝐀𝐂𝐄 𝐀𝐑𝐄𝐀")
Evaporation being the surface phenomena increases with increase in surface area.For eg: wet clothes are spread out so that with increase in surface area evaporation takes place faster and clothes become dry up quickly.

color{red}("𝟐 𝐓𝐄𝐌𝐏𝐄𝐑𝐀𝐓𝐔𝐑𝐄")
Evaporation increases with increase in temperature. This is because as the temperature is increased the particles present at the surface get the required kinetic energy so that they can overcome the force of attraction and escape quickly in air

color{red}("𝟑 𝐇𝐔𝐌𝐈𝐃𝐈𝐓𝐘")
Humidity is the amount of water vapour present in air. The air around us cannot hold more than a definite amount of water vapour at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases. Therefore evaporation decreases with increase in humidity in surroundings.

color{red}("𝟒 𝐖𝐈𝐍𝐃 𝐒𝐏𝐄𝐄𝐃")

With the increase in wind speed, the particles of water vapour move away with the wind, decreasing the amount of water vapour in the surrounding. Therefore evaporation increases with wind speed.

color{green}("𝐂𝐎𝐎𝐋𝐈𝐍𝐆 𝐄𝐅𝐅𝐄𝐂𝐓𝐒 𝐎𝐅 𝐄𝐕𝐀𝐏𝐎𝐑𝐀𝐓𝐈𝐎𝐍:")

color{green}(•) In an open vessel, the liquid keeps on evaporating. The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation. This absorption of energy from the surroundings make the surroundings cold.

color{green}(•) When we pour some acetone over our palm then the particles gain energy from our palm or surroundings and evaporate causing the palm to feel cool.

color{green}(•) After a hot sunny day, people sprinkle water on the roof or open ground because the large latent heat of vaporisation of water helps to cool the hot surface.

color{green}(•) During evaporation, the particles at the surface of the liquid gain energy from the surroundings or body surface and change into vapour. The heat energy equal to the latent heat of vaporisation is absorbed from the body leaving the body cool. Cotton, being a good absorber of water helps in absorbing the sweat and exposing it to the atmosphere for easy evaporation.

color{green}(•) Let us take some ice-cold water in a tumbler droplets of water are seen on the outer surface of the tumbler. This is because the water vapour present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which can be seen as water droplets.