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# Why are people saying that the radius of the observable universe is 46.5 ly

1. Feb 28, 2010

### zeromodz

We can only see 13.7 billion years away from us in all directions. The edge of the observable universe may now be 46.5 billion light years away, but we still can't see that far currently. I thought the observable universe was only as far the light as traveled and that is only 13.7 billion years. Why are people now saying that its 46.5 billion years? The light hasn't traveled that far, its just where the edge of what we see now is 13.7 billion years ago which is 46.5 billion light years away.

2. Feb 28, 2010

### mgb_phys

The universe is expanding.
If it was stationary we could only see things appx 13.7bnlyr away, but things that were very close to us (or where we would eventually be) at the start of the universe have now moved to a point 46.5Bn lyr away while the light was on-route.

note - relativity doesn't put any limits on the speed the universe can expand, because it isn't transfering information

3. Feb 28, 2010

### map19

This is not a simple matter of travelling at c over a period of 13.7Bn years.
the Hubble factor is about 70km/s per megaparsec
that's about 20km/s per Mlightyear distant.
All objects beyond the Hubble sphere are moving away faster than the speed of light.
mgb_phys is quite correct. because there is no frame of reference for the expansion of the universe it is not limited to lightspeed.
Normally we measure the redshift of a frequency emitted by a distant star to estimate its distance from us. You would expect redshift factor (Z) to be 1 for stars moving away at c. In fact it is about 1.5. This is down to the curvature of spacetime.
We currently can receive signals from stars etc moving away at about 4c which equates to about Z = 10.

4. Mar 1, 2010

### Chronos

~46 Bly is a confusing, unnecessary and unprovable [model dependent] concept. 13.7 Bly is our observational limit.

5. Mar 1, 2010

### map19

No it's not. It's our Hubble sphere.

6. Mar 4, 2010

### Shootist

Inflation produced a Universe larger than the speed of light would allow.

So, you will never be able to "see" beyond the point where the universe re-ionized (became transparent to photons).

7. Mar 4, 2010

### magnusrobot12

So wait, you are saying that the universe is not 13 billion years old. Its 46 billion years old? What the hell. The age of the universe was one of the few things i understood about astronomy. I guess not.

8. Mar 5, 2010

### sylas

The age of the universe is not the same as the distance to the observable horizon.

The universe is expanding. We know this as well as we know just about anything in science.

The "observable universe" means everything that we can see. However, of course, we see things very far away as they were very long ago. So "observable universe" usually means all the stuff we can see, whereever it is now.

The most distant light, which is about 13.7 billion years old, is the cosmic background radiation. That light was emitted about 0.00038 billion years after the Big Bang, or about 380,000 years after the Big Bang. What we see is actually hot glowing gas, mostly hydrogen, at an enormous redshift of about 1090, so that the light is no longer hot yellow light as emitted from a hot plasma, but is now microwave radiation.

Now... how far away is what we are looking at?

Different ways to give a distance

That's going to depend on how you define distance. There are lots of ways to define distance in cosmology, and they are different, because of the consequences of expansion.

One way to define distance is light travel time. The light took 13.7 billion years (the age of the universe less a tiny fraction) to get here.

Another way is "proper" distance -- this is the distance what you could measure if all of space was full of identical rulers, and you just add up all the rulers at any given instant in "proper" time between two locations.

SO... do we mean proper distance THEN when the light was emitted, from that gas to whatever stuff we were formed from as it was at that time?

Or do we mean proper distance NOW, from wherever that hot hydrogen is now: presumably all formed up into galaxies and so on like we are?

So far, I have given three different ways of defining distance; there are others!

Note that all these definitions all give values that are "model dependent"; in the sense that obtaining a distance using observable information (like redshift) requires calculations that use the model. The age of the universe is just as model dependent as the other definitions. Everything in science depends on some kind of model, or theory. The most useful distance definition of these three is probably the "proper distance now" definition, which is what is used in the Hubble relation, and which can be calculated using the ΛCMD model of the Big Bang.

You may find Professor Ned Wright's cosmology tutorial to be useful. Part 2 gets into the different ways distance is defined in cosmology. This is a widely recommended resource. He also gives a Cosmology Calculator, which can be used to find the distances to things in the universe, given the observed redshift, and given a particular model. The default parameters give the current best known model of the universe.

Calculating the distance to the edge of the observable universe

Type in 1090 for "z", and look at the result for "Flat" universe, or "General" (since the initial parameters are set up for the flat case anyway).

We have:
• The age of the universe is 13.666 billion years
• The light travel time is 13.665 billion years
• The comoving radial distance, which goes into Hubble's law, is 45.648 billion light years.

That last value is the radius of the observable universe. It is the "proper distance" to all the stuff we can see, but taken out to whereever it is NOW.

The proper radial distance at the time the light was emitted is not given with the calculator, but it is 45.648/(1+z) = 41.841 million light years; the universe has expanded by a factor of 1091 since then.

Some people are confused by this, as it looks like that stuff must have been moving faster than light. Quite so... it is indeed. Or, more correctly, the distance between us and that stuff is increasing at more than 3 times the speed of light, as the universe expands. (This rate of increase of the "proper distance" is not really the speed at which anything is moving through space. It is the rate of change of a separation, which turns out to be not quite the same thing.)

The reason we can see stuff that has a cosmological recession velocity greater than light speed is because that as light crosses space, it passes into regions that are receding more and more slowly. Eventually light crosses into regions receding at less than the speed of light. From that point, the light starts to get closer with time, in the proper distance co-ordinate system, and eventually it comes right into our local region of space, and we see with it. This is very non-technical, and like any non-technical answer it's wrong on some of the details; I'm just trying to give what may be a helpful intuition around a common stumbling block.

Cheers -- sylas

PS. After some discussion with other SAs, I have reworded some of this post to replace "measured" with "defined" in a number of places. We can't "measure" distances directly. The best we can do, at present, is measure things like the frequency of light, from which we can obtain a redshift, and then from that we calculate distances or ages, using some model.

Last edited: Mar 5, 2010
9. Mar 5, 2010

### magnusrobot12

Thank you very much sylas for taking time to answer my question. I think i understand what you are saying, but i still need some time to digest it all. Best always, Magnus

10. Mar 5, 2010

### Redbelly98

Staff Emeritus
I have a followup question to the ambiguity in defining distance. Presumably all these definitions become equivalent for objects that are close enough to us. We can agree on how far the Andromeda galaxy is from the Milky Way, for example.

So my question is, at what distance do the various definitions start giving significantly different answers? Would that correspond to when the recession velocity becomes relativistic?

11. Mar 5, 2010

### sylas

I'd say it is when the redshift becomes non-negligible, but perhaps that is a detail. If there is a difference in the scale of the universe between when the light was emitted and when it is observed, then distance definitions start to diverge.

For those interested in all the technical detail, I recommend Distance measures in cosmology by David Hogg (also at arXiv:astro-ph/9905116. It is intended to be purely pedagogical; to teach about the different definitions and how to calculate them.

Ned has described his calculator in some detail in A Cosmology Calculator for the World Wide Web, also at arXiv:astro-ph/0609593.

And then there are the non-technical explanations for various definitions. People who agree about how to use and calculate these distance values will still sometimes get into ding-dong fights over how best to explain them for others. My advice is to have a look at the various intuitive explanations, remember that every non-technical explanation omits something that someone considers important, and don't worry about it. Here's my own quick attempt, aiming to be really concise and not trying to cover everything. Because it is concise, each of these descriptions is incomplete and really needs a bit of technical detail to be defined unambiguously. Those who want that should read the references. I'm using Ned's variable name conventions.

If you look at Hogg's paper, you'll see a few additional definitions; and some of them are in Ned's calculator as well. I'm just going to give values for co-moving distance (Dnow) and light travel time (Dltt), but here are some other definitions you may see around the place.
• The co-moving distance is just the distance out to whatever we are looking at, but measured right now as if by a whole sequence of synchronized rulers at the same time. Same thing as "proper distance now". (Dnow)
• Light travel time, or lookback time. How long the light has been traveling. (Dltt)
• Transverse co-moving distance is the same as line of sight co-moving distance in a flat universe, which is what I am considering. In general, curvature can make a difference for large distances.
• Angular size distance. The distance you would expect normally given the angular size of an object in the sky by comparison with its real size. (DA)
• Luminosity distance. The distance you would expect normally given the luminosity of the object in the sky by comparison with its real luminosity. (DL)

Here is a table of values for different redshifts that are calculated from Ned's calculator using default parameters, which give a good match to our universe (Ωm = 0.27, ΩΛ = 0.73, H0 = 71). The redshift is z, and the cosmological recession velocity (for this model) is v, given as a fraction of c. The distances are in Giga Lightyears. The universe, in this model, is about 13.666 Gyear old.
$$\begin{array}{l|lll} z & v & D_{ltt} & D_{now} \\ \hline 0 & 0 & 0 & 0 \\ 0.01 & 0.010 & 0.137 & 0.137 \\ 0.1 & 0.098 & 1.286 & 1.349 \\ 0.5 & 0.445 & 5.019 & 6.137 \\ 1.0 & 0.785 & 7.731 & 10.819 \\ 1.408 & 1.000 & 9.082 & 13.779 \\ 2 & 1.24 & 10.324 & 17.105 \\ 3 & 1.53 & 11.476 & 21.071 \\ 10 & 2.29 & 13.183 & 31.506 \\ 100 & 3.06 & 13.649 & 42.157 \\ 1000 & 3.31 & 13.665 & 45.587 \\ 100000 & 3.37 & 13.665 & 46.507 \end{array}$$

I'm not sure if that's going to help much, but there you go. I'm not even sure that the numbers are even used much for anything other than writing press releases to help people get a picture of what the universe is like. But I do think it can be worth nutting through what the numbers mean and how they are obtained to get a better appreciation of what an expanding universe is all about.

Cheers -- sylas

Last edited: Mar 5, 2010
12. Mar 6, 2010

### Redbelly98

Staff Emeritus
Last edited by a moderator: Apr 24, 2017
13. Mar 7, 2010

### Chronos

My view is redshift gives us a fairly unambiguous measure of distance to an object when the photons we now observe were emitted. It is not an ideal unit, but, more easily understood than 'distance now', IMO.

14. Mar 7, 2010

### sylas

Sure. What makes it stand out is that it is the observable quantity, and not model dependent, and you can use it as a co-ordinate. It is equivalent to using "a" (scale factor) as a co-ordinate.

It's understandable, but it isn't a "distance", and using it to identify the edge of the observable universe tells you nothing at all. The edge of the observable universe is, by definition where the redshift diverges to infinite values. The redshift can be used as a kind of "time" like co-ordinate, however, since a given scale factor, in FRW models, identifies a hypersurface with a unique proper time... at least in models with no collapse.

It is not the same thing as light travel time, of course, which is one of the various model dependent quantities that can be calculated, given redshift and a specific model.

Cheers -- sylas

15. Mar 7, 2010

### physixlover

thanks sylas that was a very good explanation

16. Mar 8, 2010

### Ich

Some additional information on the distances sylas mentioned. I'll refer to http://www.astro.ucla.edu/~wright/cosmo_02.htm" [Broken]; there are redshift-distance diagrams for different universe models at the bottom of the page.

That's an observable, and its definition is straightforward. If you choose your coordinates such that space is flat, it's clear that this distance is exactly the distance at the time of emission.
Therefore, in a flat FRW model like LCDM, it increases with redshift as we see further and further. When the source is (now) so far away that the emission time approaches the big bang, the object was actually very near then, so that the angular distance shrinks and approaches zero again for the (now) most distant objects. You can see this behaviour in the LCDM diagram to the right.
Also interesting: In an empty universe (middle diagram), FRW space is not flat, so the above reasoning is invalid. However, there is a flat space foliation of empty spacetime: the standard Minkowski metric, of course. Scroll up to the spacetime diagram in special relativistic (=Minkowski) coordinates; you see that "We also see that our past light cone crosses the worldline of the most distant galaxies at a special relativistic distance x = c*to/2.", so that the distance at the time of emission is to/2=1/(2H0). This means: H*D approaches 1/2 for the most remote objects.

This is also an observabe, but it's not as straightforward as angular size distance: the luminosities are compared as if the emitting object were at rest wrt the observer, z=0. If the object is receding, as all distant sources are, their luminosity suffers from the http://demonstrations.wolfram.com/RelativisticHeadlightEffect/" [Broken]: they appear dimmer (=further away)than an object at rest at the same distance. Therefore, luminosity distance systematically overestimates the distance by a factor $\sqrt{1+z}$. That's the main reason for the discrepancy between Dnow and DL in Ned's diagrams.
So: For large z, luminosity distance does not correspond to any meaningful distance measure. The necessary correction for redshift is intentionally being omitted, as it would mix two observables. DL is a good observable, but a bad distance measure.

Now for the theoretical distances:

One important thing here: comoving distance is not a distance! It's rather a meaningful way of naming different members of the canonical family of observers, as it does not change with time.
[ personal opinion] Based on the unchanging comoving "distance", it is often claimed that such observers have no relative motion. In this paradigm, the increasing "actual" distance (see below) - a phenomenon normally known as "motion" - is dubbed "expansion of space". That's ok, but be warned: using every decent distance measurement you like, comoving observers actually have relative motion. Call it what you like, expansion is motion. [/ personal opinion]
If multiplied with an appropriately defined scale factor, it becomes the

"cosmological proper distance"

That's the distance you are most likely to see in a popular account (okay, maybe second rank after light travel time), on which all those statements like radius of the universe = 46 Gly or recession speed = 3.5 c are based.
It's called "proper" distance, because it can be traced back to what a suitable set of rulers would measure (see sylas' definition of "proper distance now"), and agrees to first order with any other sensible distance definition.
It is a common misconception that cosmological proper distance is as close to our common understanding of "distance" as it can get in cosmology. And that, consequently, every couterintuitive feature of those are a genuine physical conundrum, illustrating how cosmology defies common sense, rather than mere coordinate artifacts.
In reality, cosmological proper distance is measured with a set of rulers which are all in relative motion, while our intuitive (and SR-type) definition would be a set of rulers at rest wrt each other. The difference is very important when we deal with relativistic velocities, especially when the motion of the rulers changes with time (varying Hubble parameter).

Last edited by a moderator: May 4, 2017
17. Mar 8, 2010

### sylas

Thanks Ich, that was a very good explanation.

That also is precisely how I think of the matter.

That is an excellent point. I have in the past been inclined to single out "proper distance" as the one which is closest to common understanding of distance, but as you note, the fact that the rulers are all moving (co-moving, in fact) means this not true. I take note and will revise my own attempts to describe the various distance definitions in use accordingly.

Thank you very much for this -- sylas

18. Mar 10, 2010

### DrChinese

Nice post, sylas! Includes all the key ideas together in a concise and explanatory fashion. Thanks for taking the time to write this.

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# Covid19 Recovery Rate by Categorized by State at the end of October 15th 2020

The recovery rate is calculated as a total number of recovered by total number confirmed cases.   Based on the recovery rates, we have ranked the state reporting.

The states in Red represent the states that have Republican Governors and Blue are Democrat Governors. The percentage in parenthesis are recovery rate calculated.

Recovery Rate  =   (Recovered / Confirmed) * 100

Related References::   TrueFairNews Covid Dashboard, CovidTracking.com

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All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO and Advanced Virgo O3 data

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, Abbott, R., Abe, H., Acernese, F., et al. (in preparation). All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO and Advanced Virgo O3 data.

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Abstract: We present results of an all-sky search for continuous gravitational waves which can be produced by spinning neutron stars with an asymmetry around their rotation axis, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. Four different analysis methods are used to search in a gravitational-wave frequency band from 10 to 2048 Hz and a first frequency derivative from $-10^{-8}$ to $10^{-9}$ Hz/s. No statistically-significant periodic gravitational-wave signal is observed by any of the four searches. As a result, upper limits on the gravitational-wave strain amplitude $h_0$ are calculated. The best upper limits are obtained in the frequency range of 100 to 200 Hz and they are ${\sim}1.1\times10^{-25}$ at 95\% confidence-level. The minimum upper limit of $1.10\times10^{-25}$ is achieved at a frequency 111.5 Hz. We also place constraints on the rates and abundances of nearby planetary- and asteroid-mass primordial black holes that could give rise to continuous gravitational-wave signals.

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# effect of heat on nitrates

The small cations at the top of the group polarize the nitrate ions more than the larger cations at the bottom do. The next diagram shows the delocalized electrons. In most cases, it will not relieve an attack that has already started because it works too slowly (the extended-release form releases medicine gradually over a 6-hour period to provide its effect for 8 to 10 hours). Amateur title Nitrates have a useful role in angina. Missed the LibreFest? Start studying The Effects of Heat on the Carbonates and Nitrates in Group 1. Write an equation to show the effect of heat on: i) Potassium nitrate, KNO 3 ii) silver nitrate, AgNO 3. A bigger 2+ ion has the same charge spread over a larger volume of space, so its charge density is lower; it causes less distortion to nearby negative ions. Introduction Heat storage is one of the key technologies to improve the storage capacity of renewable energy and to realize the efficient utilization of off-peak power.Molten salt is an efficient heat transfer and heat storage material. All the nitrates in this Group undergo thermal decomposition to give the metal oxide, nitrogen dioxide and oxygen. Cured meats may contain nitrates as preservatives. The carbonate ion becomes polarized. A common example of an inorganic nitrate salt is potassium nitrate (saltpeter). The inhibitory effect of sodium nitrite increased roughly ten‐fold from pH 7 to pH 6. The oxide lattice enthalpy falls faster than the carbonate one. Additional uses of commercial nitrate and nitrite include food preservation (added to processed meats like bacon) and the production of munitions and explosives. It explains how the thermal stability of the compounds changes down the group. Given the following information below: Adults with specific rare metabolic disorders may also be at risk. Legal. These compounds are white solids and brown nitrogen dioxide and oxygen gases are also given off when heated. Its molecular weight is 331.2098 grams per mole. Example 1: The effect of heat on potassium nitrate crystals If you heat potassium nitrate crystals, they melt and fizz, giving off oxygen gas. if you constructed a cycle like that further up the page, the same arguments would apply. The safety of use of nitrates during pregnancy and breastfeeding has not been established. The cycle we are interested in looks like this: You can apply Hess's Law to this, and find two routes which will have an equal enthalpy change because they start and end in the same places. Sometimes, though, conditions such as diarrhea and dehydration (not enough fluids in the body) can make nitrates change to nitrites in greater amounts. Lahvanya Raoov added • Describe the action of heat on the hydroxides and nitrates of the listed metals to To do. If this ion is placed next to a cation, such as a Group 2 ion, the cation attracts the delocalized electrons in the carbonate ion, drawing electron density toward itself. This form of nitrate is used to reduce the number of angina attacks. The effect of nitrate content of nitrocellulose on the onset temperature and peak temperature of decomposition process; sample mass 3.0 mg (the nitrate content of the samples was—sample 1: 13.9, sample 2: 13.5, sample 3: 12.9 and sample 4: 12.5% nitrogen). Determine its temperature and record it at time =0 in table I below.Answer the questions below, Place 50cm3 of 2M hydrochloric acid into a calorimeter/200cm3 plastic beaker wrapped in cotton wool/tissue paper. Remember that the reaction in question is the following: $XCO_{3(s)} \rightarrow XO_{(s)} + CO_{2(g)}$. The calculated enthalpy changes (in kJ mol-1) are given in the table below (there is no available data for beryllium carbonate). More polarization requires less heat. Subject: Chemistry. If "X" represents any one of the elements, the following describes this decomposition: Down the group, the carbonates require more heating to decompose. The Thermal Stability of the Nitrates and Carbonates, [ "article:topic", "enthalpy", "lattice enthalpy", "authorname:clarkj", "carbonate ion", "showtoc:no", "Nitrates", "Thermal Stability", "Polarizing", "Carbonates", "Group 2", "enthalpy cycle" ], https://chem.libretexts.org/@app/auth/2/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FBookshelves%2FInorganic_Chemistry%2FModules_and_Websites_(Inorganic_Chemistry)%2FDescriptive_Chemistry%2FElements_Organized_by_Block%2F1_s-Block_Elements%2FGroup__2_Elements%253A_The_Alkaline_Earth_Metals%2F1Group_2%253A_Chemical_Reactions_of_Alkali_Earth_Metals%2FThe_Thermal_Stability_of_the_Nitrates_and_Carbonates, Former Head of Chemistry and Head of Science, The Solubility of the Hydroxides, Sulfates and Carbonates, Group 2: Physical Properties of Alkali Earth Metals, The effect of heat on the Group 2 carbonates, The effect of heat on the Group 2 Nitrates, Explaining the relative falls in lattice enthalpy, information contact us at info@libretexts.org, status page at https://status.libretexts.org. A shorthand structure for the carbonate ion is given below: This structure two single carbon-oxygen bonds and one double bond, with two of the oxygen atoms each carrying a negative charge. The nitrates are white solids, and the oxides produced are also white solids. In that case, the lattice enthalpy for magnesium oxide would be -3889 kJ mol-1. Country icon breaks own rule on political statements. Another study described the effects on the nitrate content of vegetables boiled in water for five or fifteen minutes. Silver nitrate is a compound. Start studying The Effects of Heat on the Carbonates and Nitrates in Group 1. The inter-ionic distances are increasing and so the attractions become weaker. A small 2+ ion has a lot of charge packed into a small volume of space. Learn vocabulary, terms, and more with flashcards, games, and other study tools. In real carbonate ions all the bonds are identical, and the charges are distributed over the whole ion, with greater density concentrated on the oxygen atoms.In other words, the charges are delocalized. View More Chemistry Questions and Answers | Return to Questions Index. The nitrates are white solids, and the oxides produced are also white solids. The smaller the positive ion is, the higher the charge density, and the greater effect it will have on the carbonate ion. Once eaten, nitrates convert to nitrite. This process is much more difficult to visualize due to interactions involving multiple nitrate ions. Usually nitrates that enter the body by eating or drinking leave the body without harm. The effect of various heating rate on heat of decomposition for nitrocellulose with 13.9% nitrate content (sample 1). The nitrates are white solids, and the oxides produced are also white solids. Describe one method used in preparation of Nitrogen. The lattice enthalpy of the oxide will again fall faster than the nitrate. Brown nitrogen dioxide gas is given off together with oxygen. Caddie's blunder costs golfer shot at U.S. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. The enthalpy changes for the decomposition of the various carbonates indicate that the reactions are strongly endothermic, implying that the reactions likely require constant heating to proceed. Brown nitrogen dioxide gas is given off together with oxygen. All Rights Reserved | Home | About Us | Contact Us | Copyright | Terms Of Use | Privacy Policy | Advertise. Subject: Chemistry. Don't waste your time looking at it. nitrate exposure that can result in serious health effects in infants. Calculate ?H for the reaction; Repeat the experiment to complete table 1.Answer the questions below, Place 20cm3 of 0.2M copper(II)sulphate (VI) solution into a calorimeter/50cm3 of plastic beaker wrapped in cotton wool/tissue paper.Record its temperature at time T= 0.Stir the solution with the thermometer carefully and continue recording the temperature after every 30 seconds .Place all the (1.5g) Zinc powder provided.Stir the solution with the thermometer carefully and continue recording the temperature after every 30 seconds for five minutes.Determine the highest temperature change to the nearest 0.5oCAnswer the questions below, © 2008-2021 by KenyaPlex.com. The carbonates become more thermally stable down the group. The Effect of Heat on the Group 2 Nitrates. Email info@curriculum-press.co.uk Phone 01952 271 318 Resources The oxide ion is relatively small for a negative ion (0.140 nm), whereas the carbonate ion is large (no figure available). For example, for magnesium oxide, it is the heat needed to carry out 1 mole of this change: $MgO_{(s)} \rightarrow Mg^{2+}_{(g)} + O^{2-}_{(g)}$. Next: Write a summary on comparison between oxides of nitrogen.Previous: Describe the preparation of ammonium solution. a. The amount of heating required depends on the degree to which the ion is polarized. When you’re studying about effect of heat on nitrates you are looking on the outcome of heating nitrates. August 2020 16:52:09 Download New comment(s) added. On that basis, the oxide lattice enthalpies are bound to fall faster than those of the carbonates. List of known side effects. The effect of heat on the Group 2 Nitrates The Group 2 nitrates undergo thermal decomposition to the metal oxide, nitrogen dioxide and oxygen gas. The nitrate ion is bigger than an oxide ion, and so its radius tends to dominate the inter-ionic distance. This page examines at the effect of heat on the carbonates and nitrates of the Group 2 elements (beryllium, magnesium, calcium, strontium and barium). This is one reason vegetables and fruits, though high in nitrates, are never as harmful as they are not exposed to such high temperatures. on Chemistry Level 10. Lattice enthalpy is more usually defined as the heat evolved when 1 mole of crystal is formed from its gaseous ions. The effect of heat on the Group 2 nitrates All the nitrates in this Group undergo thermal decomposition to give the metal oxide, nitrogen dioxide and oxygen. Although they are potent coronary vasodilators, their principal benefit follows from a reduction in venous return which reduces left ventricular work. In other words, the carbonates become more thermally stable down the group. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. brand names, dosage, and … Rinse the bulb of the thermometer in distilled water. These compounds are white solids and brown nitrogen dioxide and oxygen gases are also given off when heated. Write an equation to show the effect of heat on silver nitrate? All the Group 2 carbonates and their resulting oxides exist as white solids. Purpose: This study investigated whether reported improvements in blood flow distribution, and the possible related effects on thermoregulation during exercise following supplementation with beetroot juice (BR), a rich source of dietary nitrate (NO 3-), are mitigated in the heat. Almost all inorganic nitrate salts are soluble in water at standard temperature and pressure. But they don't fall at the same rate. Summary The ability of aerobic and anaerobic spores, after various degrees of heating, to produce macrocolonies in media containing different concentrations of sodium chloride, potassium nitrate and sodium nitrite has been examined. The inter-ionic distances in the two cases we are talking about would increase from 0.365 nm to 0.399 nm - an increase of only about 9%. Record its temperature T1.Using a clean measuring cylinder, measure another 50cm3 of 2M sodium hydroxide. This is an AS Chemistry PowerPoint Presentation on the effects of heat on s-Block carbonates and nitrates. Side effects include nausea, headache, and hot flashes. Forces of attraction are greatest if the distances between the ions are small. on Chemistry Level 10. The goal of this study is to understand and quantify the effect of temperature on nitrate removal and production efficiency in bed form‐induced hyporheic zones. Nitrates (drugs or medications) are prescription drugs used to treat and prevent angina (heart pain, chest pain). The balanced chemical equation for this reaction is 2 Pb (NO 3) 2 (s) produces 2 PbO (s) + 4NO 2 + O 2 (g). State the observation made in the combustion tube during preparation of ammonia, Date posted: February 21, 2019. Nitrosamines can form if you cook nitrates or nitrites at high heat. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. Topic: Nitrogen and its Compounds. Unwanted effects such as flushing, headache, and postural hypotension may limit therapy, especially when angina is severe or when patients are unusually sensitive to the effects of nitrates. Determine the temperature of the sodium hydroxide T2.Average T2 andT1 to get the initial temperature of the mixtureT3.Carefully add all the alkali into the calorimeter/200cm3 plastic beaker wrapped in cotton wool/tissue paper containing the acid. By using aqueous sodium chloride, describe how a student can distinguish calcium ions from lead ions. Nitrates may make you feel dizzy. The argument is exactly the same for the Group 2 nitrates. Negative health effects of nitrates in drinking water. Number of times cited according to CrossRef: 61. CuSO, Calculate the molar enthalpy of formation of carbon(II)oxide (CO) given : ?H?c of carbon-graphite = -393.5kJmole, Calculate the molar enthalpy of formation of methane (CH4) given that ?H?c of carbon-graphite is -393.5kJmole, Primary and High School Exams in Kenya With Marking Schemes. The lattice enthalpies of both carbonates and oxides fall as you go down the Group because the positive ions are getting bigger. Lead (II) nitrate is also called lead nitrate or plumbous nitrate. 2. Most metal nitrates decompose to produce a metal oxide, nitrogen dioxide and oxygen. Here's where things start to get difficult! All the carbonates in this group undergo thermal decomposition to the metal oxide and carbon dioxide gas. Again, if "X" represents any one of the elements: $2X(NO_3)_2(s) \rightarrow 2XO(s) + 4NO_2(g) + O_2 (g)$. in To do. Nitrate consists of nitrogen and oxygen. This video is an experiment to show the effect of heat on lead nitrate. If you aren't familiar with Hess's Law cycles (or with Born-Haber cycles) and with lattice enthalpies (lattice energies), you aren't going to understand the next bit. Write an equation to show the effect of heat on: i) Potassium nitrate, KNO 3 ii) silver nitrate, AgNO 3 brand names, dosage, and drug interactions are provided. Explaining the trend in terms of the polarizing ability of the positive ion. The effect of heat on the Group 2 nitrates. Using an energy level diagram calculate the ?Hs of ammonium chloride crystals given that. Brown nitrogen dioxide gas is given off together with oxygen. Detailed explanations are given for the carbonates because the diagrams are easier to draw, and their equations are also easier. Unfortunately, this book can't be printed from the OpenBook. Brown nitrogen dioxide gas is given off together with oxygen. Lesson Summary. The term "thermal decomposition" describes splitting up a compound by heating it. When lead (II) nitrate is heated, it decomposes into lead (II) oxide, nitrogen dioxide and oxygen. Trump left speechless over question about lies. Ascorbic acid must be added to foods in the United States that use sodium nitrate, because it decreases nitrosamine formation. Nitrites can combine with amines, products of protein breakdown in meats, to form nitrosamines, potentially harmful substances. Watch Queue Queue. You can dig around to find the underlying causes of the increasingly endothermic changes as you go down the Group by drawing an enthalpy cycle involving the lattice enthalpies of the metal carbonates and the metal oxides. Nitrosamines can form if you cook nitrates or nitrites at high heat.25 If the attractions are large, then a lot of energy will have to be used to separate the ions - the lattice enthalpy will be large. Both carbonates and nitrates of Group 2 elements become more thermally stable down the group. Group 2 nitrates also become more thermally stable down the group. Lattice enthalpy is the heat needed to split one mole of crystal in its standard state into its separate gaseous ions. In the carbonates, the inter-ionic distance is dominated by the much larger carbonate ion. High levels of nitrate can pose a risk to babies less than six months who are formula fed and the unborn foetus of pregnant women. Action of Heat on Nitrate Salts Nitrate salts also undergo decomposition on heating. Write a summary on comparison between oxides of nitrogen. None of the primary stresses had any significant impact on the nitrate reducer community. Sodium nitrate and potassium nitrate decompose to produce nitrite salts and oxygen. Read chapter ECOLOGICAL EFFECTS OF NITRATES, NITRITE, AND NITROSAMINES: Nitrates: An Environmental Assessment... Login Register Cart Help. Watch the recordings here on Youtube! Write a equation to show an effect of heat on silver nitrate….. Continue to order Get a quote. My Friends and I doing some experiments on adding heat to carbonates, nitrates and, hydroxides , games, and other study tools effect of heat on nitrates density, and their resulting exist. Ions are small electron density around the oxygen atoms than near the carbon free. And analyzed the pertinent coupled processes of fluid flow and temperature‐dependent biogeochemical reactions eating or drinking leave the oxide. 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