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

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3answers
34 views

Gas pressure within containers [on hold]

If, hypothetically, a gas had no inner pressure, and it was made to fill up a container. If, then, the pressure within the container was increased by filling it up with yet more gas, until high ...
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1answer
37 views

Why does stagnation pressure reduce across a normal shock?

I am seeking an explanation for this graph where the subscript "1" refers to the supersonic region and the subscript "2" refers to the subsonic region present beyond a normal shock. The static ...
0
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1answer
31 views

Why do molecules in a gas not generally arrange themselves at the distance of minimum potential energy (Lennard-Jones 6-12 potential)

As the title suggests, why is this? Is it because the distance of molecules in a gas is too large (compared to in liquids/solids)? Or are there other reasons for this?
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2answers
33 views

estimating deviations from ideal gas behaviour

How can one estimate the pressure at which argon atoms show deviations from ideal gas behaviour due to the finite size of the atoms? I have tried Taylor expanding the hard sphere gas equation: ...
3
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1answer
42 views

Behavior of atom's wave packets in a gas

It is my understanding that the wave packet of a free localized particle spreads with time. My question is what is the best description of the particles in a gas inside a closed container: Do they ...
0
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0answers
13 views

Kinetic gas theory: How large are rotational and vibrational energy for a linear diatomic molecule?

Let's say one has given a temperature of a simple linear diatomic gas like Hydrogen $H_2$. From the temperature one knows the energy of the gas, but how does this energy "split up" to the different ...
0
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1answer
49 views

How does pressure change over time in an open box?

Imagine that you have a 1 cubic meter metal box with two 20 mm diameter holes. One of them is connected to an air-compressor that constantly pressurizes the inside of cube. Let's say 5 atm. The other ...
-1
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1answer
64 views

Deriving Ideal Gas law from Hamiltonian Mechanics

I just don't understand the explanation in Wikipedia. Is there a nice & elegant way of arriving at the Ideal Gas Law from Hamilton's Equations?
3
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8answers
254 views

Ideal gas law: Will the piston move at all?

We have the following experimental setup: Before the experiment starts: $$p_1=p_2; \space V_1=V_2; T_1=T_2+\Delta T$$ The experiment starts and both the containers are heated so that the ...
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2answers
64 views

Intuitive explanation of the shape of the Maxwell-Boltzmann distribution

At higher temperatures (for an ideal gas), the Maxwell-Boltzmann distribution is spread more widely and has a lower maximum. At lower temperatures, the spread is much more narrow and the peak is much ...
3
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2answers
69 views

Ideal gas equation and atmosphere of Venus

I'm teaching myself some basics of the ideal gas law and working out simple density equations for atmospheric gases at various altitudes. When I applied the gas law to Venus' atmosphere at its ...
0
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2answers
36 views

Density of air using ideal gas law

I need to find the density of air using (I think) the ideal gas law. I have calculated $V$ of an ideal gas at s.t.p. to be $.0224m^3$. I am asked to find the density of air knowing it's temperature ...
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2answers
44 views

Approximating Gas Density

So this was a random thought I had that I thought would be fun to mess around with using an Arduino and some sensors, but after the difficulty I've had I'm just curious to see if it can be done at ...
0
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2answers
41 views

Does the increase of pressure of a gas also increase the energy?

It says that in adiabatic process, the heat is constant but the temperature is not. My question is, if you increase the pressure, the temperature is going to rise as pV = kT. But we know that the ...
0
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1answer
17 views

What are the assumptions made when analysing a stretched elastic string from a thermodynamic aspect?

Consider a stretched elastic string. Then conducting a thermodynamic analysis of the elastic string. The approach is very similar to that used for $(P, V, T)$ systems, with the pressure and volume ...
3
votes
1answer
36 views

Balloon of ideal gas suddenly pops in the vacuum of space - final average energy per atom?

My question is: is the following thinking pretty much correct? I'm interested hearing about anything here that is fundamentally wrong. Of course there is a bit of hand waving and approximation. If a ...
0
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2answers
36 views

Mixture of different gases filling their container

If I have a closed container with a mixture of two or more gases $\rho_1$ and $\rho_2$ for instance at thermal equilibrium where $\rho_1>\rho_2$ how would I determine what percentage of the ...
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1answer
41 views

Calculation of internal energy and entropy of ideal gas

I am having some trouble with calculation of entropy and internal energy for ideal gas. All sources which provide such derivations which I managed to find either assume a priori that $U$ is some ...
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2answers
36 views

Why does an ideal gas not consist of identical molecules? [closed]

since the mass , temperature , and number of particles are the same , shouldn't the molecules be the same so that the pressure of the gad is inversely proportional to the volume.
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0answers
20 views

If Earth's atmosphere would be cooled, how would its pressure change relative to its temperature?

I have a feeling it would not behave like an ideal gas? For example, if the atmosphere were to cool down at a constant 1 atm to 90 K, oxygen would liquefy. If changing of pressure would be ...
0
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2answers
94 views

Deriving the Ideal Gas Equation

Im specifically looking at how the IGE can be derived from the kinetic theory of gasses. Most textbooks and webpages I've viewed start off with a wall that the particle is hitting and then writes an ...
0
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1answer
63 views

Pressure exerted by ideal gas on walls of container

All derivations I've come across are more or less similar to this: All of them take total momentum change as $2mv_{x}$ and divide it by total time to get the force exerted on the wall. That seems to ...
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0answers
22 views

Pressure in a balloon as a function of its diameter [duplicate]

Premise #1: Balloon is a perfect sphere Premise #2: We add water in order to increase the diameter of the balloon Is there an equation allowing us to find the pressure in the balloon, as the diameter ...
0
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1answer
65 views

What height is atmospheric pressure half that at sea level?

$PV = NT$, where T is a constant $P = \rho g h$ but I don't think this equation can hold in this form as the density is most definitely not constant as we go up in the atmosphere $\rho = ...
2
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0answers
23 views

Ratio of Stagnation to Normal Flow Properties in Incompressible Flows

I know in compressible flows the ratio of stagnation to normal flow variables is a function of the Mach number and usually the specific heat ratio. Does this ratio mean anything for incompressible ...
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0answers
25 views

How do I compute mass flow rate for a compressible fluid?

Consider the vacuum chamber in the figure. If a hole with cross section area $A_{cs}$ is created, how can I approximate the maximum mass flow rate, $\dot{m}$, for a compressible fluid (e.g. air)?
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0answers
48 views

Is it possible to consider PV diagrams without the equations of state?

Suppose that we have the equations of state for a particular system, or equivalently, that we have the fundamental relation $S = S(U,V,N)$. If we want to write down a PV diagram it will be quite ...
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1answer
51 views

The average value of the electric polarization of an ideal gas

An ideal gas consisting of $N$ molecules possessing an electric dipole moment $\mathbf{d}$, placed in a constant electric field intensity $\mathbf{E}$. Need to calculate the average of magnitude of ...
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0answers
25 views

What is meant by a “change in volume of a system”?

I keep getting confused when my professor talks about the change in volume of a system. Sometimes it seems as though he's talking about the volume of the gas and at other times he might be talking ...
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1answer
50 views

Free expansion of ideal gas, transient phase (3 questions)

We all know the classic scenario of free expansion. A contained gas expands into a vaccum and in the end we have $\Delta T = \Delta U = \Delta H = 0$ and $\Delta S = R \ln \frac{V_2}{V_1}$. This is ...
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5answers
52 views

How Heat is constant in adiabatic process

Consider adiabatic cylinder with a piston attached. $Q=0$ in this case and Work done is equal to change in internal energy. If I do work on the piston then its internal energy increases and so its ...
0
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1answer
62 views

Chemical Potential in the canonical and grand canonical ensemble

I'm studying the ideal Fermi gas from "Statistical Mechanics", by R. K. Pathria. In particular, the following formula, which can be found on page 237: \begin{equation} \mu=\left(\frac{3N}{4 \pi g ...
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2answers
21 views

Would a hybrid mixed medium balloon allow you to use less helium to lift equivalent weight?

Suppose you had two balloons, one inside the other (a inside b). Would filling balloon "a" with the 80% nitrogen/20% oxygen mix you find in the surrounding air at ground level, and then filling ...
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1answer
56 views

Why does the expansion of gas into a vacuum mean that we have less information about the system? (entropy)

I'm reading through Statistical Physics by F. Mandl and in the chapter about the 2nd law of thermodynamics he states that: The basic distinction between the initial and final states in such an ...
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1answer
33 views

Calculating heat absorbed from expanding gas [closed]

I'm trying to calculate the amount of heat absorbed per kg of different types of gas, namely compressed air and carbon dioxide. Starting with carbon dioxide, I found that the Joule-Thompson ...
0
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0answers
18 views

pipette waterfountain

Place the tip of a pipette in some hot water. Cover the other end with you thumb. Invert the pipette and water sprays out nearly two metres. Is the cool air in the pipette being heated by the hot ...
1
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1answer
108 views

Compute $\langle x^2\rangle$ for gas of non-interacting particles in a quadratic potential

Consider a 3d gas of $N$ non-interacting identical particles in a quadratic potential, where the Hamiltonian $H$ is: $$ H = \sum_{i=1}^N \bigg( \frac{p_i^2}{2m} + \frac{k}{2}x_i^2 \bigg). $$ After ...
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1answer
54 views

Can't change in momentum be negative?

I was going through a derivation, of Ideal gas equation, PV=1/3 mnc2 and the book showed the following... But I know that change in momentum should be final momentum-initial momentum. But if it is so ...
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votes
1answer
33 views

Calculate the pressure in a container given moles and volume [closed]

Say there are two containers with the same volume. The first has a temperature T and pressure P and contains 1 mole of $O_2$. The second has a temperature 2T and contains 1 mole of $He_2$. I'd like to ...
0
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0answers
33 views

Acceleration of an bubble under the sea [duplicate]

An air bubble arises from the bottom of the sea. Find its acceleration if resistance force is proportional to $\rho Av$ where $\rho$ is density of water, $A$ is cross section area and $v$ is velocity ...
3
votes
1answer
89 views

Can the internal energy of an ideal gas system increase as temperature decreases?

If $\Delta U = Q + W $ Then adding $x$ moles of an ideal gas of lower temperature into a system of internal energy $U$ would increase $U$ as the kinetic energies of the molecules of the colder gas ...
3
votes
2answers
110 views

Gases Expanding and Bonding in the Vacuum? Frozen Clouds

Why do gasses expand in space rather than attract forming a liquid? Do some gasses attract or bond when they get colder and what would be the characteristics of it in space? Would it be like powder ...
2
votes
1answer
57 views

Kinetic theory of physics [closed]

$$E = (3/2) kT$$ For average kinetic energy of a molecule gas.The constant $k$ does not depend on the type of molecule. Can this result be true for both hydrogen and chlorine?
0
votes
1answer
47 views

Understanding the relation between pressure, ideal gas and, volume

I was given the following formula which is used for ideal gasses: $$pV = nRT$$ where: p:pressure V: volume n: number of moles R: gasconstant T: temperature now when speaking about vaporpressure ...
0
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0answers
60 views

When does $PV = const$ stop being true?

My problem is the following: a 15-liters cylinder contains air compressed at 370 bar. How many liter will flow out of the cylinder once uncompressed at 1 bar? I thought that I could use $PV = const$ ...
0
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2answers
48 views

Reversible expansion paradox

consider a mole of an ideal gas enclosed in a container with a mass-less piston undergoing isothermal reversible expansion. now we know that in an reversible process the system and the environment ...
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0answers
68 views

Calculate Liters Remaining in a CO2 gas cylinder/bottle [closed]

I know: The gas is CO2 (very close to 100% CO2) V - The Volume of the Cylinder (constant) P - The pressure of the Cylinder (from a sensor) T - The temperature of the Cylinder (from a sensor) I ...
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2answers
56 views

The Balloon Model for Human Ventilation

The balloon model is often used to show how ventilation works in the human lungs. You pull on the diaphragm, expanding the volume of the container, and the balloon begins to fill up. My understanding ...
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1answer
46 views

How long it takes till the gas reservoir is empty?

We have a gas reservoir of internal pressure $p$ filled with an ideal gas of volume $V$. The gas is leaking to outer atmosphere till the internal pressure equals atmospheric pressure $p_0$. The ...
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1answer
80 views

if there is Ideal Gas constant, then do we have real gas constant?

We have Ideal gas constant for ideal gases. But ideal gas is very hard to make or to be found. So we have real gases in nature. Now there is 'real gas equation' (also called 'Van Der Waal's equation') ...