# Questions tagged [ideal-gas]

A gas that behaves as randomly moving, non-interacting molecules. This allows a simplified equation of state.

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### In ideal gas $\partial_V(PdV)_T=P$

First $\partial_V(PdV)_T=\partial_V(PV)_T=P$ However, if write it by chain rule and $P=nRT/V$ $\partial_V(PdV)_T=P\partial_V(dV)_T+\partial_V(P)_TdV=P\cdot 1+\partial_V(P)_TdV=P+P=2P$. What's wrong ...
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### Is RMS velocity of gas particles always larger than the average velocity?

Is the root-mean-square velocity of gas particles always faster than the average velocity? I've done a couple of calculations with both and that seems to be the case; however can you make a formal ...
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### Why does frequency of collision increase as volume decreases?

Today I was presented with the following scenario: A syringe with one end sealed and with a frictionless piston is dipped into cold water. What is the change in frequency of collision(ie, more or ...
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### Ideal gas assumption for the Temperature Jump Distance calculation

I want to calculate the contact conductance between two surfaces that have a thin layer of air (on the order of micrometers) between them. A quick literature review shows that the heat transfer ...
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### Why does $H_2$ have $C_V$=$7/2 R$ at high temperatures, while the total number of degrees of freedom is 6?

The two hydrogen atoms have 6 degrees of freedom in total. Of them, $3$ contribute to translation, $2$contribute to rotation and $1$ contribute to the vibration. I know that the vibrations motion is ...
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### How do I calculate the height of a given that a bubble rises from the bottom of the lake to the top of the lake? [closed]

I am stuck on a physics problem which involves calculating the depth of a lake given that a bubble increases two times in volume as it rises from the bottom of a lake to the top of the lake. The ...
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### Ideal gas in piston with resistor, isothermal expansion, calculate velocity

I have this problem from Resnick's Physics, 5th ed, problem 31-15, sorry I only have the Spanish version (i'll translate): A resistor R=550 ohm, connected to an external battery, is inside an ...
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### Feynman Lectures I 40: Is the homogeneity of the Maxwell-Boltzmann distribution a result of, or a pre-requisite for its derivation?

I refer to hand-waving a lot in this post. That is not to say that it was in appropriate. Feynman pretty much said at the outset that his treatment of thermal physics was going to be less than ...
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### Does the saturated vapor pressure depend on the external pressure or just only temperature?

So far I understand that the saturated vapor pressure is the pressure exerted by a substance in liquid (or solid) vapor equilibrium, and that this pressure depends on the temperature of the system. ...
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### Difference between ideal gas law and saturated vapor pressure

Little bit confused on what each of these concepts are. So far i understand that the ideal gas law tells us how much pressure an amount of gas exerts on the walls of a container. I also understand ...
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### Why the force is equal to minus the variation of the momentum for a gas particle hitting the wall?

Why when one calculates the force exerted by a gas on the wall we say that the force is equal to (for a single particle ): F = - $\Delta p$ . But to me , it should be : $F = (p$f $- p$i ) $= -p$i - \$...