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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Why is the expansion of the piston and subsequent pressure drop shown as a positive mathematical term here? [closed]
My understanding is that we have an intake and pressure rise of p1*v1. The second term indicates both valves are closed and there is an expansion in volume and drop in pressure. Why is this a positive ...
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Pressure of a gas on the inside walls of a cylinder canonical ensemble
First post on here. I need some clarification on this topic. I have an ideal gas rotating with angular velocity $\omega$ in a cylinder of radius $R$ and lenght $L$. Working with the canonical ensemble,...
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How do we know the strength of interactions in degenerate matter?
I have read that when modeling degenerate matter we treat it like a gas(high-speed particles and very few collisions) but almost all states are filled up.
First of all how do we know that collisions ...
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Interpretation of the ideal gas single particle partition function
When considering an ideal gas composed of identical particles, in the semi-classical case, one can find that the single particle partition function is equal to:
$$Z(1,T,V) = \frac{V}{\Lambda^3},$$
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Brilliant's question on air pressure
I have always thought that as temperature increases the pressure does as well in an ideal gas, of course I know the air in the atmosphere isn't exactly an ideal gas but I would've thought that the ...
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Name of Pressure for real gas
Actually I was reading through the book, when I noticed this plot.
I am curious how all those isotherms pass through the same point, which leads me to wonder if there is a pressure for which the ...
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Integration bounds for the canonical ensemble's partition function
As far as I understand, when calculating the partition function we are summing over all of phase space.
So, for ideal gas for example we have
$$H =\sum\limits_i\frac{p^2_i}{2m}$$
and so
$$Z=\int\...
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Slow expansion: Work done by gas vs. Work done by environment
Suppose an ideal monoatomic gas expands and fills a container of volume $V,$ where one wall is a movable piston.
The text-book scenario of "reversible adiabatic expansion" 1 is that there is ...
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Is there a wavelength shift between sunlight observed from the ISS versus from Earth's surface?
As gasses are not ideal in transmitting sunlight. Are there differences between sunlight observed from beyond the Earth atmosphere and the one observed from the Earth surface? If so, what are they?
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Should the air specific heat ratio be included in the ideal gas law or not?
As you can see, both equations use the ideal gas low with the universal gas constant in J/kg.k
Both equations are used in published articles as follows:
"Application of dynamic programming to the ...
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Proportionality of Pressure and Temperature in defining Absolute Temperature scale
I am studying thermodynamics and came across this kind of loop:
First, an absolute temperature scale is attempted to be defined as follows
Assume that temperature is proportional to the pressure of ...
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Can ideal gas equation $PV = nRT$ be used in the intermediate stages of a irreversible and reversible process?
Suppose we have two processes, one is reversible and the other is irreversible. The ideal gas undergoes from state A to state B in both processes.
I want to know that can I apply the formula $PV = nRT$...
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During evaporation, why would we expect temperature of the gas at the interface to be lower than the temperature of the liquid?
This paper says that, from the kinetic theory of gases, we expect temperature of the gas at the interface to be lower than the temperature of the liquid. Could the experts here please explain it?
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Contribution of rotational mode in ideal gas law
The ideal gas law is very accurate for an $N_2$ gas when the temperature is around 300K and the pressure is around 1atm. At these conditions, $N_2$'s compressibility factor is 0.997, which means that ...
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Calculating partial pressures of real gases in a ternary mixture
I need some help on how to calculate the partial pressures of a ternary mixture using the Peng-Robinson equation of state (PR-EOS) instead of the ideal gas law.
I need to prepare a mixture of three ...
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Origin of ideal gas fluid dynamics equations including the adiabatic index
I was given a system of equations that supposedly describes the fluid dynamics of an ideal gas.
The equations are:
$$
\begin{align}
&\frac{\rho}{m} = \frac{p}{T} &\text{(ideal gas law)} \\\\
&...
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What exactly is the translational partition function for a single particle system?
I am recently reading Daniel V. Schroeder's book on thermal physics, and I am having trouble with the translational partition function for a single particle. Particularly since he defines the ...
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Helium balloons losing buoyancy in cold environment
I recently conducted an experiment in the mountains (approx 1700m above sea level) using a series of large tethered helium balloons to measure windspeed at different heights.
After only a few hours, ...
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Ideal Gas law and Universal gravitational constant
In a hypothetical universe with a different Universal gravitational constant $G$, will the nature of ideal gas change by any means?
i.e, will $PV = nRT$ be no longer applicable in that case?
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Has any work been done to describe the transient behaviour of a non-uniform ideal gas in an adiabatic process?
Recently, I've come across a discussion where a person believed classical thermodynamics predicted loss of energy in free expansion. After discussing for a while, I found out that that person made a ...
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Force and massa unit [closed]
why in this question did the question answer only perform the product between area*P to calculate the mass?
Question:
Answer:
Shouldn't the mass be calculated as $m = (P \times A)/g$?
Considering ...
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Why is the number of microstates corresponding to a macrostate even finite for an ideal gas in a box? [duplicate]
I was looking at the Sackur-Tetrode equation which gives an exact formula for the entropy of an ideal gas. I tried to relate it to Boltzmann's famous $$S = k_B \ln(W)$$ where $S$ is the entropy and $W$...
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Diffusion of van der waals gas
the problem is diffusion of non-ideal gas
i think, in this situationm the change of internal energy, work, and heat during process is zero because this process is free expansion(diffusion)
but, how ...
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Source of Taylor's "equation of state for a perfect gas"
What is the derivation of Taylor's "equation of state for a perfect gas (10)" in his 1941 paper?
What does it even mean?
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Dewpoint of a particular place
can dewpoint of a certain room change if I decrease the temperature or increase it? And what factors does RH,Dewpoint and Saturated cloud pressure depends on?
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What is the pressure immediately after compression of air?
Rearranging the gas law equation to Pressure = nRT/V shows that a reduction in volume by 10 should yield a 10x increase in pressure.
But compressing air also causes a rise in temperature. Immediately ...
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Why doesn't $\gamma = \frac{5}{3}$ for all adiabatic processes
For monoatomic, ideal gases, $PV^{\frac{5}{3}}$ is constant. I have been told that this does not hold for diatomic, or other non-monoatomic gases. However, I derived the relationship using only the ...
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The correct formulation of temperature resistivity in Drude model
In this link the document uses $F = ma = qE$ to get drift velocity(Eq.9.6,page10), and then to resistivity(Eq.9.8,page10). But the document also said velocity due to temperature is magnitudes larger ...
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Entropy of mixing via partial pressures
I was deriving the equations for calculating the entropy change $\Delta S_M$ of the system where ideal gases are being mixed.
The first one utilizes partial pressures via Dalton's law:
$$\Delta S_M= \...
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Internal energy of a gas under motion
Suppose, there a gas in a cylinder which itself is placed on a fast moving car, will there be any change in its internal energy due to the motion of the car? Do you think it may gain some kinetic ...
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Derivation of pressure in the kinetic theory of gases
According to Wikipedia,
The pressure exerted by the collisions of the N gas particles with the surface can then be found by adding the force contribution of every particle and dividing by the ...
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Discrepancy in the Derivation of Maxwell-Boltzmann Distribution
I am reading Maxwell-Boltzmann distribution for describing the velocities of ideal gas molecules. I went through the PSE question Derivation of the Maxwell-Boltzmann speed distribution and the ...
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The mean kinetic energy of a gas particle
I'm in undergraduate stat mech/thermo. In the context of the Maxwell-Boltzmann distribution, the mean kinetic energy of a gas particle is $\langle KE \rangle = \frac{1}{2}m \langle v^2 \rangle$.
I do ...
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Counting Microstates to get the Entropy Generation in Free Expansion of an Ideal Gas
In Elliot and Lira's Introductory Chemical Engineering Thermodynamics on p.134,
the authors derive the entropy generated from an ideal gas expanding from a volume V to 2V, by the removal of a ...
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Does the density form of Ideal gas law hold under condition of changing mass?
I'm trying to get a deeper understanding of this particular form of the ideal gas law I have seen. That form is $P=\rho R T$. I believe this form is not valid when mass or volume is changing. Am I ...
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Could compression make gas colder not hotter?
In classical thermodynamics compression always makes gas hotter because of the mechanical work it inputs. However, if the particle density is too high, particles will become degenerate and obey the ...
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Trouble understanding why ideal gas law explains that can of compressed air gets cold when you spray it [duplicate]
I was told that a canister of compressed air gets cold because of the ideal gas law, you are lowering the pressure and since the density of air is the same, the temperature of the can gets cold. I was ...
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Determine the entropy of an ideal bosonic gas
I am struggling with this problem.
So we're told that any macroscopic state of a gas can be characterized by microscopic stated of a single particle. We divide the microscopic states into groups. So $...
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Validity of $C_p-C_v = R$
This might be a very novice question but i got confused over derivation of $C_p-C_v = R$ which is derived using $dQ= n C_p dT,$ which is valid only for isobaric process. Thus $C_p-C_v = R$ must also ...
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Why does the temperature of an ideal gas decrease when expanded? [duplicate]
I understand that when an ideal gas is compressed using a piston, the piston does work on the gas and increases the gas's kinetic energy (so temperature). However, I do not understand why a gas is ...
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When to use multivariable chain rule in thermodynamics?
If I take $U(P,V)$, I can do:
$$ \frac{dU}{dT} = \frac{\partial U }{\partial P } \frac{dP}{dT}+\frac{\partial U }{\partial V} \frac{dV}{dT} \tag1$$
But, I see the following used in books,
$ dU = ...
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What would be the pressure, temperature and density gradients with altitude of atmosphere with ideal gas?
What would be the pressure, temperature and density gradients with altitude of atmosphere with ideal gas considerations? That is no convection or radiation.
Most of the answers I have seen are ...
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Entropy change due to surroundings?
What is the entropy generated by opening up a vacuum chamber of volume $V$ to the atmosphere? (let's say with some constant ambient pressure $P_{atm}$)
I was reading about Joule expansion, but it ...
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Mass balance for gas in a fixed volume
I am trying to generate an equation that describes the mass balance of a gas in a fixed volume. The application is simulating the sweep out time of the cell in a laser-based instrument which measures ...
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Temperature increase in fixed volume due to gas injection
I have a vessel of fixed volume with adiabatic boundary which is initially filled with air at pressure of 1 atm and temperature of 300 K. Now, I inject air from an external source at a fixed flow rate ...
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Modeling of an ideal gas from a Classical Mechanics perspective
Say we have a box with a (large enough) side $L$ in which there is are $N$ indistinguishable particles, each having a speed $\vec{v}_i$. Let us also say these particles don't interact with eachother ...
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Virial Theorem for Gas Particles
My statistical mechanics professor stated the Virial Theorem as
\begin{equation}
\langle K \rangle = -\frac12 \sum_{i=1}^N \langle \mathbf{F}_i\cdot \mathbf{r}_i\rangle
\end{equation}
For an ideal gas ...
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What is the internal pressure of a tethered hot air balloon?
This question is for the review portion of a thermodynamics class:
A small hot-air balloon has a volume of $15.0 m^3$ and is open at the
bottom. The air inside the balloon is at an average ...
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Leaking gas tank
Say we have a rigid tank of nitrogen gas ($N_0$ molecules) at temperature $T$. The tank is in vacuum. If we now punch a small hole on the tank, the gas will leak. Assume the hole is small enough so ...
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Principal of maximum Entropy (Two ideal gases in mechanical contact) [duplicate]
Consider a container with Volume V. The container is seperated by a non-movable, impearable wall, which allows heat flow. Both subvolumes are filled with an ideal gas. We can obtain informations about ...
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