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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1answer
29 views

Would gas inside of non-compressible material be affected by pressure in the deep ocean?

I was thinking about the pressure of the deep ocean and was curious if gasses inside of a non-compressible container would experience the extreme pressures associated with great depth. I'm sort of ...
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2answers
231 views

Pressure exerted by CO2 gas vs N2O in 0.5l container

What pressure is exerted by 8g (eight grams) of N2O gas on the walls of a container that has about 0.5l (half of liter) of volume? Will the pressure be the same in case of 8g of CO2 gas? Background: ...
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What is the counter-force to suction force?

I've been thinking about air pressure and vacuums recently and a (for me at least) interesting question came to mind: If there is an area with lower pressure than the surrounding air, the air ...
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356 views

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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1answer
183 views

Is there any substance whose vapor-liquid coexistence area appears leaned?

The usual substance whose vapor-liquid coexistence area appears like that shown in following Fig.1 My question is: is there any substance whose vapor-liquid coexistence area looks leaned, i.e., $V_{...
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Is it possible to create gases with high rotational temperature and low translation temperature?

Has anyone been able to take a monoatomic gas (ex: Helium) and put it in a state where the individual atoms are moving at extremely low velocity (low "translational" temperature) but the ...
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1answer
59 views

Integral for the configurational part of the canonical partition function (classical monatomic gas)

S. Salinas, Introduction to Statistical Physics (p. 111) computes the following integral for the configurational part of the canonical partition function of a classical monatomic gas (volume $V$, ...
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2answers
235 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 ...
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0answers
17 views

Will a contained fluid and a fixed, perfectly consistent source of disturbance eventually settle into a pattern, or will it be chaotic?

Imagine you have a large room, which is completely sealed, and a cordless fan in the corner that constantly blows at a low speed. Disregarding effects like heat transfer from outside, minute physical ...
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1answer
49 views

How prioritize between conservation of angular momentum and the equipartition theorem?

In most or all description of gas equilibrium the equipartition theorem is used to motivate that energy is equally distributed between rotating and linearly oscillating modes. How can that be since ...
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176 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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1answer
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Can pre-compressed refrigerant or other gas be effectively used for air-conditioning? [closed]

Is it feasible to store a very large quantity of precompressed gas that can later be used for cooling the coils in an air-conditioner? For example, an aerosol can such as a deodorant has a cooling ...
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494 views

Why is volume of a gas in an open container assumed to be constant?

I've read this in a book When air is heated in an open vessel, pressure is always atmospheric pressure, and volume of the gas is constant. How is volume of the gas constant in this case?
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Would the relationship of pressure and volume of gas change if the gas type is changed?

Question. There is an experiment investigating how a gas's occupying volume changes when its exerting pressure alters. As a result, a graph of pressure versus volume has been plotted, which is half of ...
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2answers
258 views

Equation of motion of a gas's center of mass due to heating

So here's a pretty basic question that I don't know how to solve within standard thermodynamics. Let's say I have a container with a gas in it. I transfer heat, $Q$, to the gas from the bottom of the ...
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Latent heat and change of state

If 1kg of water at 100℃ is supplied with less amount of heat energy than the latent heat of vaporisation,what will happen to it?Does part of it undergo phase change while the rest remain same?Or the ...
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Is the van der Waals fluid viscous?

The van der Waals equation of states is well known: $$\tag{1} p(\rho) = \frac{a \rho}{1 - b \rho} - c\rho^2. $$ What is the energy-momentum tensor of this gas, considered as a fluid? Is it the simple ...
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254 views

Is a detailed absorption spectrum available for carbon dioxide from 300-1100nm?

I believe that carbon dioxide does not absorb light in the visible region, but is a spectrum available somewhere online that shows this as a fact? As in a straight horizontal line at 100% transmission?...
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How to distinguish a Continuous running Xenon lamp from a low power flash tube? How to experimentallyfind out the power rating of it?

Photos: https://www.ebay.com/itm/124318383096 https://www.ebay.com/itm/154066136022 I checked online but did not find useful information. What are some ways to know what capacitor bank voltage and ...
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40 views

Why doesn't earth have a hydrogen atmosphere if hydrogen's thermal velocity is 1.75 km/s - less than 1/6th of earth's escape velocity? [duplicate]

I have read that in order to retain a gas, a planet's escape velocity must be at least six times the thermal velocity of that gas (I understand that this is just an approximation of the Maxwell ...
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2answers
585 views

How many Degrees of Freedom do Linear Triatomic Gas Molecules Have and Why?

I read this in one of my textbooks that stated Linear Triatomic Gas Molecules like CO2, HCN, CS2 in which all the atoms are linear, the total number of degrees of freedom are Nf = NT + NR + NV where ...
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Does gas spread out equally everywhere?

An excerpt from this page: Gases can fill a container of any size or shape. It doesn't even matter how big the container is. The molecules still spread out to fill the whole space equally. That is ...
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3answers
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Modelling gas concentration in a room with exhaust fan [closed]

Asumme a ceramic kiln is placed inside a room of volume $V \ m^3$. There is an exhaust fan installed in the room to extract all the kiln fumes to the outside of the room (and building) with a constant ...
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1answer
359 views

Hydrogen & Noble Gases in a Microwave

I was watching some Youtube videos of people microwaving helium and neon in a microwave. I could not find anything showing hydrogen in a microwave. However, as I was watching the videos I noticed ...
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0answers
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The model of a free particle in a box as an approximation for the translational motion of a particle in a gas

According to the book Introduction to Physical Gas Dynamics (starting from page 120), the translational motion of a particle in a gas in thermal equilibrium may be approximated by a free particle in a ...
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542 views

Van der Waals equation of state plot limitations

When I plot the van der Waals equation of state in terms of Pressure (bar) versus density (mol/L) for propane at 400 K, $$P=\frac{RT}{\big(V_m-b\big)}-\frac{a}{V_m^2}$$ in terms of density, $$P=\...
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2answers
181 views

Is the pressure in a pipe equal the pressure in the tank?

In my example, there is a tank which is holding gas under pressure. Connected to this tank is an output pipe. Assuming the pipe is the same diameter for the entirety of its length, would the pressure ...
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1answer
87 views

Does the gravitational force of a gas change with its temperature? And why?

I have read the paragraph below, somewhere- Consider a sphere filled with gas. It will generate a spherically symmetric gravitational field outside itself, of strength proportional to the total mass. ...
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6answers
2k views

Why can’t you feel the collision of each air molecule?

The molecules in a gas move very fast because of its thermal motion. But why can’t we feel the hit of each of the fast gas molecules?
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1answer
147 views

Density of states function for fermion gas (or gas in a box model): relation with degeneracy and modes

Consider a free fermion gas in a (cubic) volume $V$. The "density of states" function is $$g(p)=\frac{V}{2 \pi^2 \hbar ^3} p^2$$ This is an example of a more general type of "gas in a box" model . ...
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39 views

Principle of how refrigerator works: how is temperature dropping but pressure is not?

I'm taking "Physics of the everyday" on Brilliant. Here is the diagram of how refrigerators work: Regarding the cooling step: After exiting the compressor, this gas cools to room ...
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How does Gravity compare to the Van der Waals Forces?

Van der Waals forces' is a general term used to define the attraction of intermolecular forces between molecules. There are two kinds of Van der Waals forces: weak London Dispersion Forces and ...
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1answer
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Is steam just a combination of small waterdrops and air?

I have seen a question here about steam. It made me unsure about the nature of steam. Isn't steam a hot white cloud of water vapor? Is it just water in a gas state, so that its temperature can be ...
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1answer
444 views

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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1answer
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Question about “suction” , and overall physics, in this Whoosh Bottle Experiment

https://www.chemedx.org/blog/there-more-whoosh-bottle So this is a pretty standard "Whoosh Bottle" experiment, but with a twist, in that he covers his hand (palm) on the bottle after the ...
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2answers
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Non-popping bubbles

I used a compressed air can to clean my laptop's keyboard and speakers. After that procedure I noticed there're small bubbles in the holes of the speakers. I've tried to pop them with a thin brush and ...
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2answers
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How to dilute 5000 ppmvol of $\mathrm{CO}_2$ to obtain 250 ppm with a fluxmeter?

My problem is that I have a tank, containing $\mathrm{CO}_2$ at 5000 ppmvol, Oxygen $21\%$ vol and Nitrogen the rest, connected with a mass flow controller (flux max at $150$ ml/min). And I have a ...
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1answer
570 views

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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1answer
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What is the meaning of grain opacity and why does it affect the formation time of gas giants?

While doing research for my presentation on the formation of gas giants, more specifically the "core-accretion model", I have been stumbling across the term "grain opacity" and don'...
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3answers
66 views

How many water molecules should I put together before I can tell If it's liquid, gas or Solid?

How many water molecules should I put together before I can tell If it's liquid, gas, or Solid? I know, there isn't any clear boundary that says that you have to put $50$ molecules or $100$ ...
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3answers
369 views

Is there a number that describes a gas's departure from the ideal gas law?

When judging if relativity is important in a given phenomenon, we might examine the number $v/c$, with $v$ a typical velocity of the object. If this number is near one, relativity is important. In ...
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1answer
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Doubt about the idea of pressure exerted by a gas’ visualisation

In an educational video on derivation of the formula (3/2)PV=Kinetic energy of the gas, it was assumed that 1/3 of the particles are linearly translating along the three axes of the coordinate plane ...
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How does gravitational potential energy pertain to a single gas particle escaping the atmosphere?

What's the effective difference between a helium molecule moving at 11.18 km/s and one moving at 11.2 km/s at the edge of the atmosphere? Is the idea that, with a particle moving just below the ...
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1answer
840 views

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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Is there a gas present in the Martian atmosphere similar to hydrogen?

is there a gas present in the Martian atmosphere which could be extracted to inflate a balloon with sufficient lift to support an instrument platform for low altitude reconnaissance.
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Is there any problem in this task? (molecular formula of a gas inside a cylinder) [closed]

I got this task: A cylinder of volume V₁ = 2 L filled with gas of mass m = 7.48 g at T = 10 °C and under pressure P₁ = 2 bar Calculate the amount of gas substance in the cylinder. Infer the molecular ...
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1answer
19 views

How do turbine engines improve compression ratio?

As I have learnt from the Venturi tube that Pressure is inversely proportional to velocity. When a general aircraft is flying at say Mach 0.8 and at the same time there is a pressure decrease with ...
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1answer
42 views

What is meant by “is driven by collisions between its atoms and molecules”?" in NASA's statement?

"The behavior of a dense atmosphere is driven by collisions between its atoms and molecules." says https://www.nasa.gov/content/goddard/ladee-lunar-neon. It seems to me that a gas's behavior ...
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3answers
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What does “rarely” mean in NASA's statement: “technically referred to as an exosphere because it’s so thin, its atoms rarely collide.”?

The following statement is from this article: The behavior of a dense atmosphere is driven by collisions between its atoms and molecules. However, the moon's atmosphere is technically referred to as ...
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What is the state of the art gas concentration measurement technics, especialy for $\rm CO_2$?

Reviewing different sensors, I could find: NDIR (Nondispersive infrared sensor) is a simple spectroscopic sensor often used as a gas detector. It is non-dispersive in the fact that no dispersive ...

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