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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Do we breathe less oxygen in humid air than dry air?
In rainy season, when air is fully saturated, do we get less oxygen compared to dry air when we breathe, since the volume of breathing remains the same?
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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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Why does the volume of a liquid seem to increase and then rise when you release pressure too fast in a car's cooling system?
So I was pressure testing the cooling system of my car with a kit where you fix a cap, a gauge and a hand pump to the expansion tank and then pressurize the system to 1.5 bars (mostly European cars go ...
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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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Fermi liquid vs Fermi gas, when to use either one to model a metal?
I had been taught to consider electrons as a Fermi gas in order to calculate properties (like the heat capacity for instance) of metals even near $T=0K$.
However I'm now discovering Fermi liquids on ...
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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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If liquid and gas are both chaotic states of matter, what's the difference between them on the molecular level?
I'm a laywoman in physics and recently found myself pondering about the matter reflected in the title of this post.
To make my question more precise from the mathematical standpoint, let's suppose ...
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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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What is the difference in heat transfer between liquid-solid and gas-solid?
As far as I know solids exchange heat energy on contact the best of the three states, due to density and etc. while gasses are worst at that.
Recently I found out that, when boiling eggs, it is not ...
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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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Temperature effect of rising helium balloon in air
I wanna consider some cases and make sure if im right ,
if i have fixed volume balloon filled with helium , and let balloon fly in air ,
1)
if air temperature increases , ( without increasing temp of ...
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Do gases speed up as they leave the barrel of a gun? If so why?
I am attempting to understand the exact physics behind the recoil in guns. I made an original post on reddit here specifically asking why gases exiting a barrel after the bullet leaves causes a sudden ...
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Derivation of the collision frequency of gas with the walls of container
How can one find the rate of collision per unit area with the walls of a gas container given the distribution as $$d N\left(v_{x}\right)=N\left(\frac{m}{2 \pi k T}\right)^{1 / 2} e^{-m v_{x}^{2} / 2 k ...
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Entropy for Adiabatic - Isochoric Cycle with single reservoir
Consider the following thermodynamic cycle for an ideal monoatomic ideal gas, conducted with the help of a single heat reservoir at Tres.
It can be shown that: $$\frac{T1 \times T3}{T4 \times T2} = 1$...
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If saturated vapor does not obey ideal gas laws then how is mass of the saturated vapor proportional to the saturated vapor pressure?
My textbook mentions that unsaturated vapor obeys ideal gas law but saturated vapor does not. I could understand that air/vapor are not ideal so they won't obey ideal gas laws. But how can unsaturated ...
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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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Do electrons experience wind resistance?
Electrons have a mass, as a particle with mass, they experience most effects of objects with a mass. So do they experience any sort of wind resistance? Or is that simply explained by their cross ...
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Can we have constant volume, and pressure in a system?
I was given a system where heat was added to a mass of Nitrogen gas in a canister at constant pressure? And given the volume of the canister as 1L, I assumed that the gas would expand to fill 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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What is the correct $pV$ diagram for gas expanding inside sealed cylinder covered with piston?
I am not sure about the correct $pV$ diagram for the isobaric process of gas expanding inside a sealed cylinder covered with a piston when it is heated with candle. The best I can come up is
The zig-...
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If water vapor changes its phase, how is it possible to maintain specific volume?
I was doing my thermal engineering exercises when I encountered a problem. The problem specified a fixed and rigid container with a volume $V=0.17\ m^3$, as I have a $T-S$ diagram for water, they give ...
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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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Recombination time in air
Conditions Im interested in: air, 1 atm, 300K, very low ionization percentage, electrostatic source of ionization, reduction in ionization percentage two fold. But general answer is ok too.
Data I ...
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How much air could an activated charcoal bag or baking soda box actually purify / deodorize?
Someone I know recently bought a set of small stylish and expensive cloth bags (roughly paperback book sized) filled with activated bamboo charcoal, that you place in a room and it purportedly ...
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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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Rate of change between radius and temperature in a spherical balloon with difference of pressure proportional to the radius
I have an spherical ballon filled with an ideal gas such that the difference of pressure between the interior $(P)$ and the exterior $(P_0)$ is proportional to the radius of the balloon:
$$P-P_0 = \xi ...
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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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Liquid gas phase transition: question on convexity of free/gibbs energy and maxwell construction
I am trying to understand the liq-gas transition with van der Waals model. And I am very confused by everything. Here is what I understood and I hope you will correct me.
I consider the Free energy $F(...
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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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Flow rate of gas down a pipe at low pressures
I'm trying to understand an 'approximate derivation' of the flow rate of gas down a pipe at low pressure from my book (an example problem). It uses the result that the flux of a gas is given by $\...
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Plasma directly to Solid or Liquid and vise versa
Let's forget how and go straight to the beef and potatoes. What do you scientifically call it when a plasma turns to liquid and skips recombination, and/or condensation? What about when a liquid turns ...
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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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A simple way to make liquid oxygen at home
I have an idea to make liquid oxygen at home, but without any calculations, I am not sure whether it will work at all. The idea is based on the fact that gases tend to liquefy easily in higher ...
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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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A gas absorbs heat $Q$ isobarically
I encountered a question asking "When gas absorbs heat $Q$ isobarically, what will be its work done, change in internal energy and temperature?" The work done is obviously positive, but I ...
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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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How to Model the Forces within Inflatable Tube Man
I have a CPP setup for a cloth simulation. Currently it takes in forces for wind simulation and gravity and these forces act on individual "point masses". I'm trying to figure out how to ...
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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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