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19 votes

Why is entropy favorable?

Thermodynamics. The second law of thermodynamics states that entropy always increases in an isolated system. This is taken as a fundamental postulate---we simply accept this statement as a fact ...
a-cyclohexane-molecule's user avatar
13 votes
Accepted

Why is entropy favorable?

It appears you're looking for an ELI5-style answer, not an elaborate definition. Entropy just happens – as long as the universe isn't frozen solid, things will always be moving around, and that ...
sk29910's user avatar
  • 248
10 votes

Why is entropy favorable?

Do not think of entropy as 'disorder' as this is misleading, better is that it is a 'measure of disorder' but this is equally vague. It is better to think of entropy as the number of ways that '...
porphyrin's user avatar
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10 votes
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How is the water escaping?

There is a general belief that plastics are impermeable, probably because many liquids are stored in plastic containers. This is, however, not correct. Plastics are permeable to water and also to ...
Raoul Kessels's user avatar
8 votes
Accepted

What determines how easily a gas can diffuse into a crystal structure?

The process of heating a crystal, transforming into a different chemical, would destroy the crystal structure, making it into many small crystals or an amorphous solid. Inevitably, this makes the ...
DrMoishe Pippik's user avatar
7 votes
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Colour composition of Bromine during diffusion?

In a tall tube set upright, the density will change with height provided that the gas is not stirred. i.e. no convection occurs, so with that condition your intuition is correct. As the density (or ...
porphyrin's user avatar
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5 votes

Is the solution isotonic, hypertonic, or hypotonic?

Osmotic pressure for non-electrolytic solutes is given by $$\pi = CRT$$ where $C$ is the effective concentration of all the solutes. In our case, with multiple solutes, we simply add all their ...
Aniruddha Deb's user avatar
5 votes

Why is the Einstein relation not valid for germanium?

Quantitative explanations seems hard to come by in textbooks. In Andy Grove's (yes, the Intel guy) Physics and Technology of Semiconductor Devices (1967) one finds Experimentally, mobilities have ...
Jon Custer's user avatar
  • 8,610
4 votes

How is the water escaping?

Are the balls exactly the same size as when purchased? Perhaps the skin of the ball has expanded by absorption of some of the contents. If this has happened, an indentation could occur even without ...
James Gaidis's user avatar
4 votes

How to make equal density pool dye without diffusion

Whole milk with food coloring solved my problem. Whole milk has a specific gravity of 1.01, which allowed it to settle to the bottom around the main drains. The diffusion rate was extremely slow ...
SouthernYankee65's user avatar
4 votes

Determine direction of mass transfer

You start from a false premise, "Diffusion occurs from low to high concentration". Within a phase the expected behavior is exactly opposite. However between phases things can get more complicated. ...
Buck Thorn's user avatar
  • 22.3k
4 votes
Accepted

Graham's Law for mixtures?

It depends on the definition of average (strictly speaking on the choice of mean), as there are many types. The expression provided can be rewritten in the form $$M_{avg}^{-1/2} = \chi_A M_A^{-1/2} + \...
Buck Thorn's user avatar
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3 votes

Diffusion across a thin film

(1) determine at which side substance A will diffuse out of the membrane should I answer at the right side or that the substance stays within the membrane? Neither, because the ...
A.K.'s user avatar
  • 12.6k
3 votes

Cause of imaginary part of Warburg element in EIS

I am sorry, this is not an answer but a comment, too long to be edited in the comments section. I don't agree with "straightforward" in the sentence : " It is relatively straightforward to ...
JJacquelin's user avatar
3 votes

how to display diffusion to a young audience?

Spray perfume in the air. Ask the people around you to raise their hands when they can smell it. The people closest to you will raise their hands first. People farther away will raise then hands ...
Gimelist's user avatar
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3 votes
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how to display diffusion to a young audience?

As you mention most colored gases (Cl2, Br2, NO2, I2) are toxic and being a gas difficult to handle. Therefore not suitable for such demonstration. Maybe, you could try two small colored smoke bombs ...
Outlander's user avatar
  • 1,603
3 votes
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Where to buy/How to build a Devanathan-Stachurski cell?

I would recommend you to do a research to find scientific articles on using DS cells. In this case if you have any specific questions you can try to contact authors directly, hopefully they will reply ...
Olena K.'s user avatar
  • 166
3 votes
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Is there a consensus on whether amber can seal in air bubbles for millions of years?

There is at least a fair degree of consensus (there will always be naysayers) that the results that were performed back in the 80s and 90s by Berner and Landis were false positives that could not be ...
Buck Thorn's user avatar
  • 22.3k
3 votes
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Is pressure equalization "diffusion"?

Its not diffusion, it's effusion. The difference is that with diffusion the particles/molecules are migrating through a permeable medium where as for effusion the particles/molecules are migrating ...
A.K.'s user avatar
  • 12.6k
3 votes

When is diffusion steady-state?

There is no set answer to your problem, it depends on the geometry of the diffusional process. I give two examples. (a) Suppose there is a volatile solute in a solvent placed in a beaker and the ...
porphyrin's user avatar
  • 30.6k
3 votes

Determine direction of mass transfer

Could anyone please explain how to determine the direction of the mass transfer [...] In order for concentrations to change (given constant volumes and no chemical reactions), there has to be mass ...
Karsten's user avatar
  • 40.7k
3 votes

Is there a known relation between the diffusion of a molecule and the diffusion of the reactants?

More a set of queries and comments than an answer. I don't understand why you make A and B vary with time irrespective of your reaction scheme. You should really analyse using Fick's diffusion ...
porphyrin's user avatar
  • 30.6k
3 votes

What is the relative rate of diffusion of ammonia to hydrogen chloride, both in gaseous states?

No answer is correct, but "A" is closest to the correct answer. Heavier molecules diffuse slower than lighter ones because the same amount of thermal energy has to move more mass. However, this ...
Oscar Lanzi's user avatar
  • 58.6k
3 votes

What is b in the Gompertz model?

I can see at Gompertz function they use the formula below. See the link for Graphs of Gompertz curves, showing the effect of varying one of a,b,c while keeping the others constant $$f(t)=a\mathrm{e}^{...
Poutnik's user avatar
  • 42.3k
3 votes
Accepted

Permeability of containers to poop smells

The problem likely is not (so much) the plastic material of your container, either solid, or bag.*) Assuming there is no contamination on the outer side of the container, most likely the smells are ...
Buttonwood's user avatar
  • 30.1k
3 votes
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What is the relation of water potential with gibbs free energy?

It is not very clear, if mechanical or chemical potential is meant. but it does not matter much, as the former is the part of the latter. At higher position in gravitational potential context, water ...
Poutnik's user avatar
  • 42.3k
3 votes

Why do different places on Earth have different concentrations of particulate matter in the atmosphere?

Particulates are not dissolved in air, but suspended. Gravity operates on them. That said, sand from Africa does reach the Americas. Also, the atmosphere is not in equilibrium -- there are sources of ...
DrMoishe Pippik's user avatar
3 votes

How do concentrations of different solutes across a cell membrane affect whether water leaves or enters the cell?

The effects of multiple solutes are often considered additive, although things may get complicated at higher concentrations. In general one considers the effect of these solutes on the "activity&...
Buck Thorn's user avatar
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