Questions tagged [gas]
This tag is for questions relating to "gas", one of the four fundamental states of matter (the others being solid, liquid, and plasma). Gases follow certain laws known as the gas laws. These laws tell us about the behavior of gases i.e., the values and relations of temperature, pressure and volume etc.
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$\rm N_2O$ for tire inflation [closed]
I have a car with slightly underinflated tires, and I'm seeking out an overcomplicated solution. Let's get that out of the way first!
What's happened is my car started reporting worse fuel economy, ...
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Does increasing gas solubility rate reduce the increase of pressure when adding gas to a closed system?
Whilst I have tried to put the question in a generic form in the title, this actually relates to a specific scenario (from the realm of homebrewing, of all places) and I think I should outline that ...
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What happens to entropy during compression?
I learnt that entropy in the universe can only be created, never destroyed. (And so change in entropy can never be negative, right?)
But during compression, don't we increase the order in, say, the ...
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How can the ions in intergalactic and interstellar gas held together?
The interstellar and intergalactic medium contain huge amounts of free ions (both free protons and electrons).
However, when these particles are not stabilized in an atom because they are excited, as ...
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Why don't liquid aerosols rapidly vanish by evaporation?
Liquid aerosols are known to be relatively stable.
However, given their immense surface area and tiny volume, we would expect them to rapidly vanish by evaporation.
Why are liquid aerosols ...
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Entropy for Adiabatic - Isochoric Cycle with single reservoir
Consider the following thermodynamic cycle for an ideal monoatomic ideal gas, conducted with the help of a single heat reservoir at Tres.
It can be shown that: $$\frac{T1 \times T3}{T4 \times T2} = 1$...
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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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Why diffusion of gas in water only depends on partial pressure?
I just learned that there is a type of beetle that could dive in water carrying an air-sac for breathing, and, the air-sac could be replenished by the diffusion of oxygen in water into the sac.
I have ...
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Effect of condensation pressure drop in open flow
If saturated gas flows through a tube that is being cooled, the gas will start to condense, forming droplets at some point in the tube. Looking at the individual condensation "cells", I ...
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Type of expansion process for a tank with orifice
Consider a tank filled with gas who is being discharged via an orifice. So, the gas flowing out of the tank is experiencing isenthalpic expansion and thereby a specific temperature drop, depending on ...
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Why don't disturbances/wind move at the speed of sound in air?
Why don't sound waves move at the same speed as air that has a pressure differential? Imagine you have a box that is filled with air. One half high pressure air, the other half low pressure. They are ...
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Why should the rate of evaporation of liquids depend upon the rate at which the molecules strike the surface?
This paper says:
The development of the kinetic theory of gases led to the conclusion
that the maximum rate at a particular temperature would be given by
the rate at which molecules strike the ...
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If air was the same density as water, but still a gas, could you swim in it?
I'm not talking about normal physics here, as it would be extremely hard to get such a situation to arise, this is more a hypothetical question.
If air was the same density as water, while still ...
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Were radioactive materials used in neon indicator lamps? [closed]
Were radioactive materials used in neon indicator lamps?
Old-fashioned glow starters for fluorescent lighting
[How a glowstarter works]
often contain small traces of radioactive gas (like $^{85}$Kr or ...
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How does gravity overpower a vacuum?
While watching experiments with vacuum chambers, I had a thought.
If you put a sealed box at normal atmospheric pressure inside a vacuum chamber, pumped out the air and pierced the pressurized box I'd ...
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Why can photon be treated like gas?
In Cosmology, especially when studying Cosmic Dynamic, sometime we will treat photons as gas to calculate its pressure, but according to my understanding, photon and gas are nothing alike. Why can ...
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How does ionization of gas molecule affect the translational kinetic energy of the molecule?
Some things I understand to be true:
When we raise the temperature of a gas to around 10-20,000 Kelvin, the molecules of gas start to ionize, form a plasma, according to the Saha equation.
The ...
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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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How do I create a highly conductive vapor cloud? [closed]
I'm working on a project that requires that I create an electrically conductive gas cloud that can conduct voltages as low as 1.5v from a regular double A battery. I've been looking into using mecury ...
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Static pressure vs ambient pressure
If in a real scenario, a flat surface with a flush perpendicular closed duct of small diameter is exposed to a tangential fluid flow(laminar and naturally with the presence of boundary layer effect), ...
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Modelling the number of times a gas tank can be filled
I'm currently working on a project where I need to estimate how many times a large, high-pressure gas tank can refill a smaller tank. For this purpose, I'm using a pressure regulator to manage the ...
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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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Excluded volume in van der Waals' Equation
As per my understanding, excluded volume is defined as the volume excluded to the rest of the gas molecule's centers because of its presence. During bimolecular collisions, there is some overlap in ...
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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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Finding formulas for molar internal energy and molar enthalpy of mixing fluids
There is a Y-shaped pipe connection. One fluid flows through one pipe with molar flow $\nu_1$, molar internal energy $U_1$, molar enthalpy $H_1$; through the second pipe - another fluid with molar ...
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How can I find the fundamental equation of the system?
A gas respects the following equations
$$T=\frac 32(u+\frac 1v)$$ $$P= \frac Tv -\frac1{v^2}$$
Where $T$ is a thermodynamic temperature, $P$ is the pressure, $v$ the specific volume and $u$ the ...
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Why is the number of microstates corresponding to a macrostate even finite for an ideal gas in a box? [duplicate]
I was looking at the Sackur-Tetrode equation which gives an exact formula for the entropy of an ideal gas. I tried to relate it to Boltzmann's famous $$S = k_B \ln(W)$$ where $S$ is the entropy and $W$...
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Keeping sparkling water inside a bottle as aerated as it was before opening bottle
So when you open a new bottle of sparkling water (or soda) it's very fizzy and aerated. However, when it is stored for quite a bit (no matter how tightly you close the bottle cap) it loses some gases ...
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How it is possible to vary the pressure of a gas under constant $V$ by varying $T$ while also considering the expansion or contraction of the gas?
Is it possible to vary pressure of a given quantity of a gas without changing its volume by varying only temperature in real life? Why the varying temperature does not change the volume? Why the gas ...
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How to calculate the specific heat jump for a van der Waals gas at a non-critical volume?
I am currently self-studying Statistical Physics by Professor Schwabl and encountered a problem in the book (problem 5.5) that has significantly challenged my understanding. The problem is brief but ...
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Gas and Vapour liquefaction
I am a bit confuse in the first statement.
I think the statement is implying vapour as 'former' and gas as 'latter'. Am I correct here?
But gas can be liqufied with pressure alone below the critical ...
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Helium in Uranus atmosphere
I read that in 1986 Voyager 2 measured the composition of Uranus' atmosphere, which turned out to be composed of $85 \%$ hydrogen and $15 \%$ helium.
It's not clear to me how this relevant amount of ...
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Derivation of the state equation of a van der Waals gas. Can I invert the derivative to help me?
The state equation of a van der Waals gas is
$$\left(P+\frac{a}{v^2}\right)(v-b)=RT$$
with $a,b$ and $R$ constant. Find $$\frac{\partial v}{\partial T}\bigg\rvert_P.$$
Finding $\frac{\partial v}{\...
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What is the equation for the speed of a molecule at a specific temperature?
What is the equation for the speed of a molecule at a specific temperature? I saw two equations $v = \sqrt{\frac{3 k T}{m}}$ and $v =\sqrt{\frac{3RT}{m}}$. What is the difference?
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Why $∆U=Q_v$ only at isochoric condition for real gas?
U is a state function.So, ∆U should be same if we carry out an isochoric process from state A to State B or through any other process for real gas. And as ∆U=Qv for real gas in isochoric process, so,∆...
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Different types of pressure and their sources
I’m an engineering student. So far, I’ve learned about 3 types of pressure:
Static fluid pressure ($P=\frac{F}{A}$). This wouldn't exist without gravity. I’ve solved problems related to the force ...
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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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Apparent paradox: Mass flow rate decreases when I increase nozzle diameter
I do computational fluid dynamics for a living. I have recently been working on a case in which I simulate the flow (assumed 2D) of a compressible gas from a large chamber at pressure $P_1$, through a ...
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How to calculate the flow of air that leaks out of a container?
I cannot grasp what should be a simple gas problem (last time I worked with gas formulas was 40 years ago). Values I provide here are just for the sake of explanation.
There is a thermically isolated ...
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How do I convert weight of compressed, liquid $\rm CO_2$ in canister to cubic meters at atmospheric pressure?
I need compressed $\rm CO_2$ for a project I'm working on, and am trying to figure out how much volume of gaseous $\rm CO_2$ I get from a given weight of liquid $\rm CO_2$ in canister. As far as I can ...
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Clarification regarding 'Boyle's Temperature' definition
In the Boyles law def- "The temperature at which a real gas obeys ideal gas law over an appreciable range of pressure is called Boyle temperature."
Why "over an appreciable range of ...
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Find heat capacity of Van der Waals gas
Can anyone guide me how can I find $C_P$ and $C_V$ ? There are two equations in Heat and Thermodynamics: An Intermediate Textbook Textbook by Mark Zemansky and Richard Dittman, which I think can help ...
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A question based on the kinetic theory of gases
An insulated container containing monoatomic gas of mass $m$ is moving with a velocity $v$. If the container is suddenly stopped find the change in the temperature of the gas.
I want to know why ...
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Is this a simple proof that gas pressure is a relativistic invariant?
This is a simple thought experiment that hopefully demonstrates that gas pressure is an invariant in relativity.
Consider two very long sealed rectangular boxes that contain equal gas pressure when at ...
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Is it possible to make a dual-mode, multi-band laser?
Understanding how N2 and CO2 gas lasers work,
Is it possible to make a gas laser (i.e. with the right gas mix and excitation source) that:
has more than one mode of operation,
emits light in more ...
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Vacuum Equalization
If I have two evacuated chambers each 10m on a side. Both are strong Vacuums but one is a slightly lower pressure than the other (A is the lowest pressure vacuum [ 10x-10 tor], B is the slightly ...
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Most probable velocity of a mixture of gases [closed]
We have the average, root mean square, and most probable velocities of a gas as
$v_{av}=\sqrt\frac{8KT}{\pi m}$ ; $v_{rms}=\sqrt\frac{3KT}{m}$ ; $v_{mp}=\sqrt\frac{2KT}{m}$
For a mixture of two ...
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How do steam work in micro gravity?
Imagine an astronaut spills boiling hot coffee inside the orbiting space station, where do the steam go? I mean the coffee will likely form into many many balls but they at still very hot!
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How many degrees of freedom does a diatomic and triatomic molecule have at high temperatures?
I understand that a diatomic molecule has 3 translational and 2 rotational degrees of freedom. But since there is only 1 vibrational mode associated with a diatomic molecule and 1 vibrational mode is ...
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Is the equation for degrees of freedom $f=3N-k$ valid for all cases?
Consider the example of a linear triatomic molecule. Now at low temperatures, where we can exclude vibration, quite clearly degrees of freedom, $f=5$, with 3 translational and 2 rotational degrees of ...
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