Questions tagged [ideal-gas]
A gas that behaves as randomly moving, non-interacting molecules. This allows a simplified equation of state.
1
vote
1answer
32 views
Thermodynamics : Pressure of a gas
While reading The kinetic Theory of gases in Feynman Lectures , i was hoping for an explanation concerning the factor (2) that shows that only half of the atoms are headed towards a piston, while the ...
0
votes
1answer
10 views
How to contain air ions inside a chamber without loosing their charge?
I would like to create an experiment where I would hold ionized air molecules. Most likely negative O2-1 ions. I am looking for the most appropriate enclosure so that the ions do lose as little of ...
0
votes
0answers
7 views
How to calculate energy stored in a hydraulic hybrid system?
My understanding is that hydraulic hybrid systems have two reservoirs - one at high pressure and one at low pressure. I also understand that the working fluid can then be pumped between these two ...
0
votes
2answers
66 views
Expansion of an ideal gas at constant pressure
I approach these expansion problems like so:
The gas and the surroundings(piston+outside) are at the same pressure at first. We heat the gas. The pressure rises inside the syringe a bit. The gas ...
0
votes
1answer
30 views
Is it possible to calculate the mass of gas remaining in a cylinder simply by measuring temperature and pressure?
Given $pV=nRT$, where;
$p$ = Pressure, $V$ = Volume, $n$ = Number of moles of gas, $R$ = Gas constant and $T$ = Temperature in Kelvin.
Also, the mass can be calculated by;
$m = nM \rightarrow n = \...
0
votes
0answers
25 views
Derivation of the wind load formula
I am trying to derive the wind load formula:
$F_d = \frac{1}{2} \rho v^2 A C_d$
in which I assume the drag coefficient to be equal to 1.
My starting point is that the momentum of a rectangular wall ...
4
votes
3answers
136 views
Partial derivative of $PV=nRT$ with respect to $T$
We all know for an ideal gas $PV=nRT$ then, if we differentiate it partially w.r.t $T$ shouldn't we get
$$\frac{\partial}{\partial T}(PV)=P\left(\frac{\partial V}{\partial T}\right)_P+V\left(\frac{\...
2
votes
4answers
52 views
How can I calculate the speed at which a gas flows from one volume to another?
Suppose that there are two rigid Volumes A and B. Each of these contains a gas with know properties (pressure, temperature, number of moles, volume, composition). Suppose also that there is a pipe ...
0
votes
0answers
27 views
Why bulk modulus of air is initial pressure?
So in the definition of bulk modulus the strain part is defined as (∆v/v) where ∆v is change in volume and v is the initial volume and while driving it for air we use the ideal gas law PV= constant ...
0
votes
1answer
46 views
Heat transfer of a monatomic ideal gas at room temperature
I have done parts a) and b) but have been stuck on c) for hours I have tried to come up with a formula but can’t come up with a reasonable one - I can’t even see how it is possible. Any help would be ...
0
votes
1answer
43 views
How was $C_p-C_v=\left(\frac{\partial P}{\partial T}\right)_{Vn}\left(\frac{\partial \:V}{\partial \:T}\right)_{Pn}$ dervied
I found the following relationship whilest on wiki reading up about heat capacity and cannot figure where the relationship has come from. Would it be possible for someone to maybe outline where it has ...
1
vote
1answer
50 views
Thermodynamics - please check my proof that $\partial C_p/\partial p$ = 0 for an ideal gas
Prove
$$\left(\frac{\partial C_p}{\partial p}\right)_T = 0$$ for an ideal gas.
All the $\partial$s are partial derivatives
Please check to see if this makes sense.
We know that
$$C_p = \left(\...
1
vote
1answer
96 views
Why does entropy of an ideal gas break the third law of thermodynamics? [duplicate]
I was recently looking at the entropy equation for an ideal gas, show below
$$S=NR\left\{\frac{5}{2}+\ln\left[\frac{V}{N}\left(\frac{2\pi mRT}{h^2}\right)^{3/2}\right]\right\}$$
And what troubles me ...
0
votes
0answers
33 views
Does thermal equilibration affect compression work for an ideal gas?
Consider compression of an ideal gas that is uniform in pressure but nonuniform in temperature, from volume $V_1$ to $V_2$. For simplicity of the problem let's say the gas is divided into 2 regions $A$...
0
votes
1answer
100 views
Partition Function of an Ideal Gas
Which is the correct partition function for an ideal (bosonic) gas at high $T$:
1) Sum over the number of particles in each momentum state:
$$ z_{\vec{p}} = 1 + e^{- \varepsilon_{\vec{p}}/T} + ... = ...
1
vote
2answers
40 views
What happens to pressure when a liquid turns into a gas in a confined chamber?
I'm doing an experiment requiring immense pressures. Since I do not have access to a pump that can create these pressures I settled on something different...
Instead of using a pump I want to utilize ...
0
votes
0answers
32 views
How long does it take a gas to equilibrate with a container's temperature?
Initial Conditions in a vessel:
P~my unknown, but ~100torr, V=5000cc, T=35C, gas is 50/50 N2/He
Laser drill a hole in the initial volume of diameter=10mils through a chamber wall thickness of 0.75mm.
...
0
votes
0answers
26 views
What happens when a photon hits a particle (radiative heat transfer, photoelectric effect)?
By relating temperature to particle motion, the kinetic theory of gases gives an intuitive explanation of conductive heat transfer; faster particles collide with slower ones to transfer kinetic energy....
0
votes
0answers
52 views
Assumptions and limitations for ideal gas
Assumption: In the assumption for ideal gas law, it is stated:"The time it takes to collide is negligible compared with the time between collisions." For, this assumption, can i just say there is only ...
0
votes
1answer
27 views
Determining Gas Constant $R$ from Boyles Law?
I have done an experiment (Boyles Law experiment using Boyles Law Apparatus) in order to determine the value of the gas constant $R$. I have also taken into account the dead space volume in my ...
0
votes
0answers
8 views
Insert sensors in an aerostat with helium?
Hy is possible for you insert sensors (to calculate pressure and temperature) inside an aerostat with helium ?
I ask this because...
I have an helium balloon anchored to the ground by a rope with a ...
0
votes
0answers
22 views
Is the Ideal gas approximation still valid if I have sizeable dynamic pressure
Say, if I have a hose blowing or sucking air into/outo a bigger compartment, can I still regard the static preassure as obeying ideal gas law?
0
votes
1answer
33 views
How to calculate the specific weight of air?
First of all sorry for my bad English ...
I have to calculate the specific weight of air knowing that in the air there is actually a small percentage of water vapor.
Therefore the specific weight of ...
1
vote
0answers
27 views
Modell for the buoyancy of a hot air balloon
I was just working on a problem concerning a ballon for my introdouction to thermodynamics class. The helium ballon is emerged in air and surrounded by earths gravitational field, which shall be ...
3
votes
1answer
50 views
Why use a cube as a reference volume in the kinetic theory of gases?
In basic kinetic theory we often use cubes. For example, the derivation of the ideal gas law is done with a cubical volume. Is a cube necessary for it to work? If not, wouldn't a sphere be more ...
0
votes
3answers
60 views
Work done on a gas enclosed in a container
According to everywhere work done on system of a gas is equal to $p\,\mathrm dV$ but here $p$ is just the external pressure. Shouldn't internal forces be considered while calculating work done thus ...
0
votes
0answers
26 views
Derivation of density of states for a gas with $N$ states
I am trying to find any information on the derivation of the density of states for a system with periodic boundary conditions in 3D. I know how it works with 1 particle since I have seen the ...
2
votes
2answers
84 views
Does $PV\propto T$ apply to a photon gas?
For an ultrarelativistic ideal gas, I know that
$p=\frac{u}3$;
$TV^3 =$ constant;
$pV\propto T$.
For a photon gas, I know that the first two results apply as well. However, I am unsure if the third ...
0
votes
1answer
37 views
Bouyancy of ozone gas
If ozone is $O_3$ why is it an outer layer of the atmosphere? It seems $O_3$ would sink in a solution of $O_2$, rather than float on it.
0
votes
0answers
43 views
Ideal gas as balls in boxes in different ensembles
I have some questions about the ideal gas in different ensembles. Often boxes with moving balls are used to explain an ensemble. Now I am confused what the difference would be in the corresponding ...
0
votes
1answer
50 views
Applying ideal gas law to every day problems
Three classical examples of seeing the ideal gas law in action:
crumpled water bottle in cold car
crumpled water bottle after your flight lands
fridge door harder to open a second time after first.
...
2
votes
0answers
32 views
Boltzmann transport equation for granular gases
I am researching about granular gases and their collisions, and have come across this Boltzmann transport equation:
$$\frac { \partial f ( v ) } { \partial t } = \iint d u _ { 1 } d u _ { 2 } f \left( ...
0
votes
2answers
51 views
Deriving pressure from particle velocity: missing 1/3 factor
Let us assume we have a perfect gas, isotropic, homogeneous, inside a cube of side a.
We want to calculate the pressure as a function of the velocities of the particles inside.
We must find the ...
1
vote
2answers
42 views
What is the criteria of trapped ideal gas to form Bose-Einstein condensate (BEC)?
If we have ideal gas of bosons in a trapped harmonic potential, is the only necessary thing for BEC is a temperature less than the transition temperature? Or is there any other things we should keep ...
-3
votes
2answers
67 views
Compression of gas [closed]
What happens when a gas kept in a metallic container is suddenly compressed via a piston and left for some time? Does the pressure increase or decrease?
0
votes
1answer
55 views
How was Maxwell able to derive velocity distribution? [closed]
Did he assume that their velocities follow some kind of statistical distribution and fit the parameters accordingly. Or did he mathematically prove it?
2
votes
2answers
131 views
Thermodynamic Entropy seems to be contradictory
For an ideal gas the entropy change with energy is inversely proportional to temperature:
This must yield:
$$S=\frac 3 2 k_B \ N ln(T)$$
For various reasons, this equation is hard to find.
...
4
votes
2answers
106 views
Does quantum gases obey ideal gas equation $ PV= nRT$?
At extremely low temperature, does an ideal gas of bosons or fermions obey the ideal gas equation, $PV= nRT$?
1
vote
2answers
64 views
Are forces of gases intensive or extensive?
What am I wrong at in here:
I read that pressure is an intensive property.
According to this and to $P=\frac{nRT}{V}$, can this be true:
$(1)$: When $V$ is constant, increasing $n$ won't increase $P$,...
0
votes
2answers
64 views
Definition of volume of a gas and Amagat's law
How would you define the volume of an (ideal) gas?
I would say it is the volume of the container holding the gas (whether it is a fixed container or a flexible one like a balloon).
However, ...
0
votes
0answers
27 views
How to find Volumetric Expansion if not given the volumetric coefficient?
I'm doing a few practice questions on thermodynamics to prepare for my exams next year and I have been stuck with this question ever since. I tried to move on to answer other questions and came back ...
1
vote
1answer
42 views
Proportionality between pressure, volume, and number of microstates for an ideal gas?
I'm pretty new to Thermodynamics, but I've been playing around with some different computations to reinforce my understanding. I came across the result $$\Omega \propto \left( PV^\gamma \right)^{fN/2},...
0
votes
1answer
25 views
What would be the total pressure in this container in accordance to the Ideal Gas Law?
If I had an apparatus such as the one below:
where each of the four blue lines represents a valve, and then I was to open the three lower valves such that the pipes connecting the three containers ...
0
votes
1answer
37 views
Does the amount/speed a balloon rises vary with the temperature of the gas inside, given a constant type and amount of gas?
I'm attempting to conduct an experiment with a balloon. I fill it up with some amount of helium. If I cool the balloon down (say with liquid nitrogen), the balloon's volume will decrease (because of ...
0
votes
1answer
51 views
Joule expansion and center of mass
This question comes from a doubt resulting from some physics forums. Similar to and related to this question, I have a doubt on Joule expansion raised by reading too much bad faith arguments.
I'm not ...
0
votes
2answers
62 views
Does Avogadro's law only apply to ideal gases?
I know the ideal gas law may change a little when for real gases or diatomic ones does Avogadro's law change too or does it stay the same?
0
votes
1answer
49 views
Limitations of converting pressure into kinetic energy
Bernoulli's principle states that an increase in the kinetic energy of a fluid occurs simultaneously with a decrease in pressure for isentropic processes. What then limits us from converting all of ...
1
vote
3answers
166 views
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 ...
0
votes
3answers
58 views
How does a gas spring work?
I read Wikipedia and do not understand the following.
If you create pressure on the gas (or any spring) it gives pressure against.
Why is the gas spring holding mass when pulled out, and while ...
0
votes
2answers
65 views
What kind of ideal gas process a positively sloped line in a $pV$-diagram represents?
I've come across an ideal gas process which can be represented by a positively sloped line in the $pV$ diagram. I found something about this on KhanAcademy, but it's simply a worked example on how to ...
