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

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32 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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0answers
23 views

What happens to the radius of a sphere if I double the number of atoms contained in it? [on hold]

I'll get a lot of downvotes eventually, but I've been trying to answer this questions for months. Scenario: Say I have a sphere containing helium. I've always wondered what would happen if I double ...
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1answer
24 views

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

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 ...
5
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4answers
2k views

Understanding mathematically the free expansion process of an ideal gas

I'm trying to understand mathematically that for the free expansion of an ideal gas the internal energy $E$ just depends on temperature $T$ and not volume $V$. In the free expansion process the ...
0
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0answers
31 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 ...
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0answers
20 views

Prove for ideal gas temperature being directly proportional to absolute temperature [closed]

I have some difficulties proving that the ideal gas temperature is directly proportional to absolute temperature defined by the second law of thermodynamics. The ideal gas temp. is defined by the ...
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2answers
110 views

If I double the amount of oxygen molecules, do I double the paramagnetic force?

Oxygen is well known to be paramagnetic. If I take one molecule, $O_2$, and measure its paramagnetic force due to externally applied magnetic field, and then add another molecule near the first ...
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1answer
39 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 ...
2
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1answer
159 views

Bernoulli Equation for isentropic ideal gas flow

If one derives the Bernoulli Equation for the isentropic ideal gas flow you get: $$ \frac{1}{2}v^2 + g z + \left(\frac{\kappa}{\kappa -1} \right) \frac{p}{\rho} = const. $$ Two questions: Is ...
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2answers
42 views

Gases Expanding Vacuum

Why do gasses expand in space rather than attract forming a liquid? Do some gasses attract when they are colder?
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2answers
105 views

physical meaning of pressure derivatives

Is there any physical meaning of the first and second derivatives of pressure with respect to time? If this helps, I am considering ideal gases.
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1answer
48 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?
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4answers
477 views

Conversion of ideal gas to real gas via $Z$ compression factor

The ideal gas equation $PV=nRT$ can be converted into real gas equation by compression factor $Z$ i.e $PV=Z~ nRT)$. My question is what is $Z$ and how does it arise? Is $PV/nRT$ a compression ratio of ...
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1answer
40 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 ...
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3answers
415 views

Why Earth's atmosphere behaves like an ideal gas?

In every book I found this sentence like an assumption, without explananions, somebody can help me understand it better?
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1answer
259 views

Gas compressed and cooled

If a certain amount of a gas is compressed into a cylinder by the action of a piston that reduces its volume (lets say at a low speed), the kynetic energy of the gas molecules increases, what is ...
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0answers
42 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 $PV = const$ ...
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2answers
43 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
24 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
31 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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2answers
174 views

Viscosity for steam in the Reynolds number

In calculating the Reynolds number for a flow of steam in a pipe, this is the general formula I am trying to use: $$Re=\frac{\rho d v}{\mu}$$ with density $\rho$, pipe diameter $d$, flow steam $v$ ...
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1answer
40 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
58 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') ...
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1answer
44 views

Filling of a gas in a cylinder

The problem statement is as follows: An insulated rigid vessel of volume $V$ initially contains $N_i$ moles of an ideal gas at temperature $T_i$. A pipe is now connected to the vessel and the same ...
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1answer
19 views

Understanding why 2*density of a isolated gas equals half the initial temperature

A vertical cylinder of cross-sectional area 0.050 m2 is fitted with a tight-fitting, frictionless piston of mass 5.00 kg. The cylinder contains 3.00 mol of an ideal gas at 227°C. At what temperature ...
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1answer
56 views

Statistical mechanics of ideal gas in a box with adsorption states on surface [closed]

Assume we have a cubic box of side length 1m with ideal gas particles inside. We assume the binding energy of a gas molecule to the wall is 1eV. One can make the simplifying assumption that: ...
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1answer
43 views

Adiabatic expansion of ideal gas and dependence of temperature on volume

We know that for an ideal gas $$PV=nRT,$$ where $P$ is pressure, $V$ volume, $n$ amount of substance in moles, and $T$ the temperature of the gas. We can easily derive that, for a (non-free) ...
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1answer
38 views

Thermal Energy in a pV diagram

I'm studying for an exam in thermodynamics and therefore going through old exams, but I am stuck on one assignment. One kilomole of ideal monoatomic gas under standard conditions is processed ...
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3answers
46 views

How do you calculate oxygen temperature as atm pressure changes? [closed]

I know that when gases are decompressed the atoms suddenly have a bunch of space and absorb all the heat around them thereby giving the effect that it is cool but how do you calculate this for oxygen ...
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1answer
30 views

Gasses and Gravity

I have two questions. First question. When gas is placed inside a container it fills the container evenly with constant pressure. If the container size varies the gas expands or is compressed but the ...
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2answers
55 views

Oblique collisions in classical gas

I am trying to simulate the collisions in classical gas. So the particles are point like and have identical mass. It is easy to find who collides with whom but the what happens to the particles after ...
1
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1answer
68 views

What is the difference between the Method of Characteristics being formulated in terms of theta & alpha and theta & nu?

So I'm doing an MSc thesis involving the method of characteristics in rocket nozzles. My lecture notes have the MoC formulated such that the positive characteristics are defined as: C+ = Tan ( ...
2
votes
1answer
28 views

Gauge Pressure and Bar Pressure [closed]

I ran into a problem trying to calculate the absolute pressure of an isolated system. I was given that the gauge pressure in a tire is 200kPa or 2 bars. To get the absolute pressure I would have to ...
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1answer
38 views

Ideal gas law with two types of gases

Suppose a container with volume $V$. If I put 2 different types of monoatomic ideal gas, say type $A$ and type $B$, such that there are $N_1$ particles of gas $A$ and $N_2$ particles of gas $B$, with ...
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1answer
41 views

Liquid phase is a highly compressed gaseous phase

$\mathbf{Q:}$ While teaching "Real Gases", my professor remarked last day that "Liquid phase is a highly compressed gaseous phase." But he did not explain the reason behind it and left it as food for ...
3
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1answer
65 views

Energy of classical ideal gas in the grand canonical ensemble

The canonical partition function for an ideal gas is $Z(N,V,\beta) = \frac{1}{N!} (\frac{V}{\lambda^3})^N$ where $\lambda = \sqrt{\frac{\beta h^2}{2 \pi m}}$ is the thermal De-Broglie wavelength. It ...
3
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2answers
37 views

RMS Speed of Gas Molecule for Polyatomic Molecules

Halliday in his book and also many people say that RMS speed, $v_{rms}$ is $\sqrt{\frac{3RT}{M}}$. However, he used this formula in showing that kinetic energy, $K$, is $\frac32kT$. but how about ...
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1answer
34 views

How does a gas emit radiation with temperature when it's particles motion are linear?

Particles in gas move faster with temperature in a linear motion (root mean velocity equation?) right? It explains increase in pressure and effusion proportional to temperature. Solids emit radiation ...
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19 views

hot air balloon and pv=nrt [duplicate]

[on hold] up vote-3down votefavorite A hot air balloon has a total mass 750 kg (not including the air in the balloon) and holds a volume of 2.8x10^6 L of air. Assume the density of air outside the ...
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2answers
965 views

Derive the Sackur-Tetrode equation

How do you derive the Sackur-Tetrode equation? I know that you must start off with the multiplicity of a mono-atomic ideal gas: ...
0
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1answer
61 views

Why is it not possible to use the ideal gas law to determine if the pressure changed in this situation?

I was given this question for my homework: A cylinder with a valve at the bottom is filled with an ideal gas. The vale is now opened and some of the gas escapes slowly. The valve is then closed, ...
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0answers
23 views

Thermal conductivity of a binary gas mixture

I want to estimate the thermal conductivity of binary gas mixture, say water vapor+nitrogen. I assume the mixture as ideal gas. The molar fraction and thermal conductivities of the components are ...
2
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1answer
75 views

What is the cause of this 'bump' in the heat capacity graph for a monatomic ideal gas?

I am trying to understand the heat capacity behaviour for an ideal gas as a function of temperature. The text I am learning from is Schroeder's An Introduction to Thermal Physics. This is an exercise ...
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1answer
44 views

What is a good software for Ideal Gas simulation?

I am looking for a software that simulates the microscopic behavior of an ideal gas, something like this: http://www.youtube.com/watch?v=tEFHkcx2cz0 (unfortunately this program is not openly ...
6
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1answer
94 views

Adiabatic expansion in the atmosphere

When an air parcel rises and cools adiabatically, it is said that there is no heat transfer as work is done on the surrounding atmosphere as the parcel expands. The parcel loses internal energy and ...
0
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3answers
61 views

If Gravity acts on the particles in the gas, why don't they accumulate on the lower surface and fall down?

A quantity of gas is enclosed in a metal cylinder fitted with a piston. There are very many gas molecules.The cylinder walls are thermally conducting. Now, the question...
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0answers
37 views

Thermodynamics: Deriving inner energy from ideal gas equation of state [closed]

If we know equation of state for ideal gas $ PV = NkT$ where $P$ stands for pressure, $V$ for volume, $N$ for number of particles, $k$ is Boltzmann constant and $T$ is temperature, how can one ...
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0answers
86 views

Time between two collisions in a 2D gas

I'm trying to code a simulation of a 2D gas in a box. The molecules are represented by circles of radius $R$ having elastic collisions with the walls only (for now). I read that the average time step ...
0
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1answer
68 views

Methane under pressure [closed]

A tank is filled with liquid methane. Then it is closed. It sits in an infinite room at STP (standard temperature and pressure). (Initial temperature is not important; assume density of liquid ...
2
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8answers
108 views

Visualising gas temperature and gas pressure

Gas pressure is created when gas molecules collide with the wall of the container creating a force. Gas temperature is a measure of how fast the molecules are moving / vibrating. However, they both ...