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.

Filter by
Sorted by
Tagged with
0 votes
3 answers
28 views

If the inclination of a cloud of oxygen in outer space is to diffuse, then how do nebulae form?

If a cruise ship-size object in outer space were surrounded by a spherical cloud of oxygen, and there were no other bodies exerting significant gravitational force in the vicinity, would the cloud of ...
user avatar
0 votes
1 answer
59 views

How comes, that my book states that internal energy is dependent on volume?

Currently I am reading in the 11 edition of Physical Chemistry, Atkins in the chapter 1st law of thermodynamics. A few pages ago I learned the following: Makes sense for now, as far as I know it ...
user avatar
  • 165
0 votes
0 answers
38 views

Cubic nature of van der Waals' gas equation [duplicate]

$V_m^3-\dfrac{RT+bP}{P}V_m^2+\dfrac{a}{P}V_m-\dfrac{ab}{P}=0$ So, At $T<T_c$ the above equation has three real roots say $V_1,V_2,V_3$, my doubt is what does this mean physically because for some ...
user avatar
0 votes
0 answers
33 views

Analogy between Curie's Law and the Ideal Gas Law

I've been trying to derive Curie's Law from the Ideal Gas Law for a while, since numerous sites on the internet state that they are analogous. However, if we apply the equivalences - $P \iff B$; $V \...
user avatar
2 votes
1 answer
49 views

Partition Function Question

I've been looking at calculating the Internal energy of a non-isothermic van de Waals gas, and in doing so have been researching the free energy and hence the partition function necessary to calculate ...
user avatar
  • 23
4 votes
5 answers
847 views

Why is there no temperature difference in the Joule expansion experiment?

The whole system is adiabatic, and no heat exchange can take place. If the volume of the gas now doubles, it should actually cool down. That's why I don't understand $dT=0$
user avatar
  • 165
0 votes
0 answers
16 views

Condensation in a mixture of gases

Say I have a cal gas of 100 ppm ethanol in a bottle at 1000 psi, balance N2. I am concerned about the ethanol condensing at low temps. The empirical Antoine eqn tells me that if ethanol partial ...
user avatar
0 votes
2 answers
33 views

Does Gas constant depend on molecular weight?

I came across the following question recently Calculate the difference between two specific heat of 1 g of helium gas at NTP. Molecular weight of helium = 4 and J = $4.186×10^7$ erg $cal^{-1}$ The ...
user avatar
  • 341
-2 votes
1 answer
26 views

Can a small amount of super-compressed gas cause much cooling upon rapid expansion and contact? [closed]

Generally, a small amount of mass in the range of $0.001$ - $0.01$ kg, even if chilled to tens of degrees below absolute zero in a hypothetical case to test extremes, even with 5000 specific heat and ...
user avatar
2 votes
1 answer
50 views

What exactly is the specific heat of a gas?

When I read that specific heat of Steam $(100 °C)$ is $2010 J/kg \cdot °C$ what exactly am I reading? What does specific heat of a gas essentially mean when it is not mentioned whether it was measured ...
user avatar
  • 21
0 votes
1 answer
45 views

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 ...
user avatar
2 votes
1 answer
31 views

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 ...
user avatar
  • 21
0 votes
1 answer
48 views

Internal Energy of Van de Waals Gas when non-isothermic

I have been looking online and at previous posts for a way of calculating the internal energy of a gas or the work done on gas due to a changing volume. The problem that I keep encountering is that ...
user avatar
  • 23
0 votes
1 answer
42 views

How do we do experiments on gases at zero Kelvin?

We say that at temperatures very close to absolute zero (nano or pico Kelvin) there is no gas, so how do we do experiments on gases at zero Kelvin, and why is Bose-Einstein described as a gas? 1995 – ...
user avatar
1 vote
1 answer
23 views

Questions about metastable van der Waals states

This is an excerpt from David Tong's Statistical Physics: My questions: Are those metastable states ("good states") taken from the Maxwell-corrected $pV$-curves (flat lines) or from the ...
user avatar
  • 177
0 votes
1 answer
42 views

How is a Carnot engine in quasi-equilibrium?

If the reversible isothermal expansion and adiabatic expansion both yield positive work (as the pv diagram indicates), it means that the gas inside the cylinder was compressed before those stages ...
user avatar
0 votes
0 answers
19 views

Why is flow more laminar in smaller tubes?

I was learning about laminar and turbulent flow in the context of breathing. This page emphasises how in larger tubes, like the trachea (main breathing tube of the body - responsible for Adam's apple) ...
user avatar
  • 2,166
3 votes
1 answer
40 views

Why is the pressure inside the bottle lower than atm pressure?

When a balloon is placed inside a bottle (covering the entranace), it will not inflate, since the bottle is already filled with air particles with no escape route. When you punch a hole in a bottle, ...
user avatar
1 vote
1 answer
51 views

Van der waals equation why should we divide excluded volume by 2?

So been looking at the correction term $b$ for the Van Der Waals equation. I understand that we look for the excluded volume. I see it as the volume where no (center of a) particle can enter. We start ...
user avatar
0 votes
1 answer
27 views

Does radiant heat energy increase the temperature of any gases it passes through?

I am in an HVAC/R technician certification class, and the instructor taught us that radiant heat energy only increases the temperature of solid objects, and the temperature of gases are not affected ...
user avatar
  • 35
1 vote
2 answers
50 views

Free expansion of ideal gas dilemma

I have a question about free expansion of ideal gas. Firstly, we will take the entire (isolated) container to be our thermodynamic system. We know that the gas in the left-part of the container has a ...
user avatar
0 votes
0 answers
27 views

Henry's Law and Bunsen's solubility coefficient

Let's say I have a known Partial Pressure P of oxygen in mmHg or kPa in blood. Knowing the temperature, I also know the Bunsen solubility coefficient or Henry’s law constant (α) from given table: The ...
user avatar
0 votes
1 answer
61 views

Ultrarelativistic gas and microcanonical ensemble

Given the Hamiltonian of the ultrarelativstic gas $H= \sum_i^N |p_i|c$, it is known that the energy is given by $E=3Nk_BT$. Is it possible to demonstrate this relation just by using the fact that $\...
user avatar
  • 1
0 votes
2 answers
92 views

Why doesn't the temperature reduce after free expansion of a gas?

I am currently studying Thermodynamics from Khan Academy. In one of their videos, Sal explains how the free expansion of a gas doesn't change the temperature of the system because the average kinetic ...
user avatar
  • 133
1 vote
1 answer
25 views

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 ...
user avatar
0 votes
1 answer
41 views

Effective optical depth using Beer-Lambert law for non-linear attenuation?

Currently I have a gas with a density that follows and inverse square law in distance, $r$. Given that I know the mass attenuation coefficient of this gas, I wish to calculate an effective optical ...
user avatar
3 votes
1 answer
97 views

Partition function for weakly interacting gases

I'm studying the Susskind lecture on statistical mechanics. A potential energy of pairwise interactions has been defined: $$\sum_{n>m}U(|x_n -x_m|)$$ We want to calculate the partition function, ...
user avatar
0 votes
0 answers
64 views

Relationship between global and local temperature?

So let's say I sum over the time experienced by all the molecules of a gas in the following manner: $$ \sum_{i} ds_i^2 = c^2 d \tau_1^2 + c^2 d \tau_2^2 + c^2 d \tau_3^2 + \dots c^2 d \tau_N^2 $$ Now,...
user avatar
0 votes
0 answers
11 views

Extracting a mass attenuation coefficient for a dilute metallic gas for visible wavelengths

Currently, I am examining the attenuation of a visible wavelength laser with an initial intensity, $I_0$ by a metal vapor (in this case Aluminium) that has a density, $\rho_g$ of around 0.02g/cm$^3$. ...
user avatar
0 votes
2 answers
49 views

Change of state of gas

Why is it necessary to liquify a gas and then kept in container? We know gases take the shape of container they are kept in. So we take a container of our desired amount and then we can collect gas in ...
user avatar
0 votes
1 answer
20 views

What does the force equation of kinetic molecular theory actually mean?

Actually I was learning about kinetic molecular theory of gases. The equation of force exerted by molecules on the wall is $$F=N\frac{mv^{2}_{x}}{L}$$ Where N is the number of particles and L is the ...
user avatar
  • 37
-1 votes
1 answer
25 views

Why is time of contact not taken in finding rate of change of momentum in derivation of kinetic gas equation?

In derivation of kinetic gas equation, the time taken for rate of change of momentum is taken as 2l/u but the force is change of momentum divided by time of contact so why are we taking time for gas ...
user avatar
0 votes
1 answer
106 views

Non-Ideal Gas Question

I have been attempting to solve a problem involving a non-ideal gas. The gas is assumed to be non-ideal and hence modelled by the Van der Waals Equation, it is considered to be pure hydrogen gas and ...
user avatar
  • 23
3 votes
1 answer
95 views

Why does the keg temperature rise after pouring a beer?

I have a refrigerated pony keg. Inside is pressurized CO2 and beer. Connected to the bottom of this keg is a weight and temperature sensor. According to these sensors when a beer is poured from this ...
user avatar
0 votes
0 answers
32 views

On the Sum of Collisions from each coordinate

I was self-reading the gas laws stuff in this book at page $18$. In chapter two author tends to derive the formula for, $$\ P=\frac{2K.E}{3V}$$ Where $P$ is pressure and $K.E$ is kinetic energy and $V$...
user avatar
  • 390
4 votes
2 answers
91 views

How is Avogadro's law tested practically?

I was reading about Avogadro's law which states that Equal volumes of all gases under the same conditions of temperature and pressure contain equal number of molecules. My question is, how can one ...
user avatar
  • 133
4 votes
3 answers
830 views

Momentum of a gas expanding into a vacuum chamber in outer space

Consider a gas expanding adiabatically from a gas chamber through an orifice into a vacuum chamber as shown in the schematic figure. In order for significant number of gas molecules (which we refer to ...
user avatar
  • 2,340
10 votes
5 answers
2k views

Can we derive Boyle's law out of nothing?

My textbook states Boyle's law without a proof. I saw Feynman's proof of it but found it to be too handwavy and at the same time it uses Boltzmann's equipartition theorem from statistical mechanics ...
user avatar
  • 390
0 votes
1 answer
34 views

Why does the average kinetic energy of particles in water involve the gas constant?

I am reading these lecture notes on statistical mechanics. On page $10$, the author asserts that the average kinetic energy of particles floating in water is given by $$\frac{3RT}{2N_A}, $$ where $R$ ...
user avatar
1 vote
1 answer
25 views

Adding extra gas to a high velocity burner but the temperature in the vessel won't rise

So I'm doing a refractory dryout of a vessel and I'm stuck at 350°C. Normally I would add some more gas to the burner and the temperature would go up, but now it just stays at the same level. I've ...
user avatar
1 vote
2 answers
44 views

Why does steam in a teapot move to the largest opening?

This morning I was making tea, and I took my teapot off of the stove and opened the spigot (where the front / whistle clasps onto) to let it cool. When I opened the spigot, steam started coming out as ...
user avatar
  • 13
0 votes
1 answer
26 views

What is the pressure at the bottom of an open-end manometer?

How do we evaluate the pressure at the bottom? My approach is to add the atmospheric pressure, pressure of the gas and pressure due to the two columns (say of height h1 and h2 respectively h1<h2). ...
user avatar
0 votes
0 answers
26 views

Can you remove air bubbles from oil by heating it just like you do with water? Does oil even have dissolved air?

I have a flat bottle filled half with water and top half with oil. It has a impeller connected with motor which slowly swirls oil and water to create beautiful lava lamp like effect. However after ...
user avatar
0 votes
0 answers
26 views

A question concerning gas diffusion

We are discussing the one dimension diffusion in a tube. To simplify the analysis, we isolate two adjacent thin layers sharing a same surface, in which gas concentration could be assumed as even ...
user avatar
  • 65
0 votes
2 answers
43 views

How a compression of gas molecules change their velocity therefore their KE?

How can a compression of gas molecules change their velocity therefore their KE? My intuition suggest me that there should be a change of mean molecule path length and so the frequency they hit the ...
user avatar
1 vote
1 answer
23 views

Pump fluid down HPHT gas well - fluid remains at top

Working offshore on a High Pressure / High Temperature gas well. We pumped 120 barrels of organic solvent into the well. The gas density was 0.3kg/m3. The fluid was 0.8kg/m3 & a boiling point of ...
user avatar
  • 11
0 votes
1 answer
37 views

The force acting on a piston in a gas canister and the movement of the piston

I apologize if this question is too simple to ask but I'm not entirely sure about the mistake that I'm making and I honestly would appreciate the help. In the cylinder of a vehicle ($r=5$cm, resting ...
user avatar
  • 103
0 votes
3 answers
345 views

Does indoor odor smell travel up or down?

Does odor smell, let's say it's from caulk off-gasing, travel upward or downward in the air? Are all odor smell lighter than air?
user avatar
0 votes
0 answers
11 views

Why does rotational collision number in dilute gases such as N2 increases with temperature?

In the kinetic theory of dilute gases, the rotational collision number and rotational relaxation time are defined as follows- rotational relaxation time = time required for the establishment of ...
user avatar
0 votes
0 answers
22 views

How to simulate gas diffusion from a mixed gas composition to room air?

I am trying to program a pretty simplistic gas model, so you can assume the most ideal situation. I have a gas circuit that can be disconnected and leak all of its containing gases into a room. The ...
user avatar
  • 101

1
2 3 4 5
13