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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Is internal energy frame-dependent? [duplicate]

In the realm of kinetic theory of gases, the internal energy of gas is solely due to the sum of kinetic energies of all particles, since kinetic energy is frame dependent I was thinking whether a ...
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(SOLVED) Calculate the velocity of a gas inputted in pressure difference

I'm trying to make a generally simple calculation but I'm not sure if I'm approaching this correctly. So as I'm making assumptions solving this problem, please comment or correct me wherever I'm wrong ...
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On internal energy conservation in a gas system

I have seen multiple questions which talk about a tank with a partition in the middle and different ideal gases on either side at some different value of pressure,volume and temperature and then they ...
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40 views

What happens when ideal gasses are mixed?

I'm sure their temperatures will be equal, but what about their volumes and pressures?How does one approach ideal gas mixing problems?
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What happens to the pressure and the temperature of a gas compressed adiabatically?

The set-up is basic. There is a piston that goes down, reducing the volume. The process is adiabatic, so the acquired energy is kept inside the gas. The ideal gas law states that as the volume ...
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What does $C_p-C_v=R$ mean? What are its applications?

So my question is: what does $C_p-C_v=R$ actually mean? It's very straightforward to derive. But my issue is, where and what use does this have in real life applications, and why is it important? All ...
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Is it possible to calculate pressure without a barometer?

For an experiment, I need to pump air into a rocket with varying volumes of water, and thus air. However, I want to keep the pressure the same. Given the amount of air a bicycle pump can pump, the ...
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Expansion of an ideal gas in an evacuated bottle having nonconducting walls

In the free expansion of ideal gas in a vacuum $dW = 0$ as $p_{ext} = 0$ and $dU = 0$ therefore there is no change in temperature of the ideal gas also. what i want to know that can the following ...
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What volume exactly does the $V$ term in ideal gas equation represent?

According to kinetic theory of gases 'the actual volume occupied by the gas molecules are negligible in comparison to the volume of the container.' I believe that this assumption is significant ...
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Pressure in a 2D Ideal Gas simulation

I am currently creating a 2D ideal gas simulator whereby the user can determine three of the four variables (P, V, n, T) and the gas would adjust accordingly. I was wondering how I could calculate ...
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162 views

Power of thermal radiation in gases

How much thermal radiation does a given volume of gas emit? Does it go according to Stefan-Boltzmann law, i.e. as $P=A\varepsilon \sigma T^4$, with $A$ as the cross-sectional area, $\varepsilon$ as ...
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133 views

How do I simulate an ideal gas?

I wish to write a simple simulation of an ideal gas, but my maths and how I should have a model based the equation isn't quite up to it. I need some help understanding the relationship between ...
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Constant RPM of Gas Compressor

I would like to improve my understanding of gas compressors. If the compressor is moving at constant RPM, does it mean that it can only allow the same volumetric flow rate at all times? So the power ...
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Using the work-energy theorem in thermodynamics

If an $n$ moles of an ideal gas (one atomic) is heated at constant volume $V$ from temperature $T_1$ to temperature $T_2$, the amount of energy heat needed can be calculated as $$ Q = nC_V \Delta T $$...
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Ideal gas and moveable pistons

Suppose there is an ideal, monatomic gas contained in a cylinder with a moveable piston and you bring that system (system = gas only) through some process. If that process changes the volume (or ...
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Finding the temperature of a gas using the $P$-$V$ diagram [closed]

I need to know a way to relate the P-V curve of an ideal gas to its temperature.I found a similar question on stackexchange but couldn't understand how the relationship between a point and the ...
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Reason for gas constant value

I know that it's derived from experimentation and it's natural but is there a specific reason that the value is $8.31\space J\space mol^{-1}\space K^{-1}\space$?
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Find the density of air at the given temperature and pressure [closed]

Find the density of air at $99$ kPa and $322.15$ K. My attempt: Let's assume that air is $78\%$ nitrogen and $22\%$ oxygen by volume. Average molar mass of air = $0.78\times 28+0.22\times 32\approx ...
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Internal energy

Internal energy at a specific state can't be calculated, but using kinetic theory of gases and the law of equipartition of energy, average kinetic energy is directly proportional to temperature. For ...
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Ideal gas formula $PV = nRT$ in Celsius scale

I was wondering how to re-write that ideal gas formula $PV = nRT$ applicable to Celsius or Fahrenheit scale. I know $R$ has unit $\frac{\mathrm J}{\mathrm{mol\cdot K}}$ and $T$ has units in K, that ...
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How do I calculate the pressure on the walls of my MD simulation?

So I've built a simulation in vpython where I have multiple hard balls that collide with each other and with the walls of the cube I've placed them in. I then replaced the values for their radius and ...
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Confused about summing over the velocity squared term

Consider a cubical box, L on each side. The box contains N molecules of ideal gas, each of mass m. All collisions are elastic. The force exerted by one molecule when it collides with a wall of ...
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135 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 ( $\...
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Why maxwells speed distribution law doesn’t violet special theory if relativity [duplicate]

As per maxwells distribution law the molecule of gas will have speed across zero to infinity with some probability function. I want to know that why the speed above speed of light is possible (i know ...
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Calculating entropy for the surroundings the logical way doesn't work

EDIT: I was missing the entropy change due to temperature change and now everything makes sense Suppose I have $n$ mol of an ideal gas in a chamber with a piston with volume $V$ at pressure $P_{1}$ ...
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Ideal gas law when diatomic molecule is about to break into constituents

Suppose we have a diatomic molecule. Its center of mass has an average kinetic energy given by $$ \frac{1}{2} (m_1 +m_2) v_{cm}^2 = \frac{3}{2}k_BT $$ and using this we can derive the ideal gas law ...
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Derive Charles's Law from ideal gas equation

For a thermodynamics experiment I had to determine the ratio of the volumes of two tanks. The process used was isothermal. I pressurized up one tank and slowly opened the valve between the two tanks ...
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156 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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How to Convert Dimension of $R$ constant of Air (J/Kg.K)?

Example) (P=nRT/V) in this equation P=nRT/V, The final dimension is achieved should be a function of pressure, But I can not understand this dimension in final (mol.J/Kg.Liter). when use in R ...
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172 views

Helium in an old mylar balloon

As a sealed mylar foil balloon ages, it deflates. I assume that this is mostly due to the monoatomic helium escaping through the envelope material. (In much the same manner as hydrogen can escape ...
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What is the volume occupied?

What is the volume occupied by 1 mole of gas at $10^{−10}$ torr, the pressure inside an “ultra high vacuum” (UHV) chamber. How do I solve this problem without being given the temperature?
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Two gases seperated by semi-permeable membrane

The problem is as follows: Two ideal gases are contained adiabatically and separated by an insulating, fixed piston that blocks the molecules of gas 2 but allows the molecules of gas 1 through(in both ...
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In a gravitational field, will the temperature of an ideal gas will be lower at higher altitude?

I know there are similar questions, but I have some arguments which seem to explain that temperature of an ideal gas in a gravitational field will be lower at higher altitudes. I am assuming that: 1....
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Why is the probability that the collision angle will be in the range of 0 to 60 degrees than in the range of 60 to 180 degrees

Pretty much the title. It is given that the probability that the collision angle will be in the range of 0 to 60 degrees than in the range of 60 to 180 degrees I don't remember seeing such statement ...
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Is it possible to increase the temperature of an ideal gas in an adiabatic sealed container with a frictionless piston for a lid?

As far as I understand it, if I pumped the piston repeatedly, compressing the gas, the temperature would go up for a second, but the minute I released the piston the higher pressure inside the ...
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Work done by ideal gas under a reversible process which is not isobaric, isochoric, isothermal, adiabatic

First post, sorry for the poor formatting. Question Consider a non adiabatic system closed to mass exchange where an ideal gas traverses along a reversible path from state: to . What is the work ...
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Infinite entropy in ideal gas

Does it make sense that entropy goes to infinity as temperature goes to infinity? For an ideal monoatomic 1D gas I have an expression for entropy \begin{equation} S=Nk_{B}Ln(\frac{Ve^{\frac{5}{2}}\...
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Would setting the ideal gas constant to $1$ yield an attractive natural temperature scale? [closed]

In this recent question, there was a comment 'The "zero point" of Kelvin is natural, but the scale is not'. This led me to wonder whether setting $R = 1$ in the ideal gas law would be an attractive ...
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Negative Heat Capacity of an Ideal Gas

Sign Conventions:- Work if done by system, heat given to system and Increase in Internal Energy implies $+$ change. Otherwise $-$. Ok, consider an ideal gas in a container with perfectly conducting ...
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Computing entropy for two ideal gas systems

I'm trying to show the processes in the following rows are different. On the left column there are two boxes of $12$ particles each. Both boxes are divided in three imaginary and equal rooms with $...
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What happens to temperature as volume increases (charles law)

Let us take Boyles law to start. Assumptions: Gas is perfect. In a massless piston that can be expanded with no friction Adiabatic If we were to decrease the volume of the piston, the pressure ...
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442 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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How do we find force to derive $pV=Nmv^2$?

Since momentum is not changing in time t , but instantaneously in very small time at wall B. Why do we write $F=\frac{2mv}{t}$? Where $t$ is (twice the distance AB)/ velocity. Why don't we take the ...
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Conversion of $R = 8317\ \mathrm{\frac{J}{kg\cdot mol\cdot K}} $ to $ 8317\ \mathrm{\frac{J}{kg\cdot mol\cdot {^\circ C}}}$

I'm trying to understand the unit conversions when one unit is obtained by shifting the value of another one by some constant. In particular, the unit conversions from Kelvin to Celsius scale: $$T(\...
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Why does molecular potential energy increase with constant temperature?

You heat up a liquid at its boiling point, and the temperature remains constant until all the liquid has turned into vapour. Since the temperature stays constant kinetic energy stays constant too, but ...
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Why doesn't the equipartition theorem force the rotational energy of a monoatomic molecule to be significant?

I'm reviewing the Feynman Lectures and in them he states that the rotational kinetic energy of a monoatomic molecule in a gas is insignificant due to a small moment of inertia. But wouldn't the ...
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Transfer of gas particles during pressure change

There is a room with a known volume. The temperature and pressure are known too (STP). It is given that the window is open and there will be a pressure drop outside due to wind. I need to find the ...
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Collision frequency of ideal gas and velocities of molecule

Is collision frequency of gas molecule $ = \frac{V_{RMS}}{\lambda}$ where $\lambda$ is mean free path. Shouldn't it be $\frac{V_{average}}{\lambda}$? (I often see that in theories books suggest that ...
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What does happen if I push a piston in an adiabatic cylinder containing an ideal gas?

What does happen if I push a piston in an adiabatic cylinder containing an ideal gas? According to Ideal Gas Equation: $$PV=nRT$$ Is it possible to predict what's going to happen? Will Temperature ...
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Thermodynamics problems with a cycle (insufficient data?)

I am having some troubles in solving the following problem a professor gave us, and in my opinion I think that either there are insufficient data or the solutions are infinite. We have a perfect gas,...