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Questions tagged [kinetic-theory-of-gases]

Questions about the assumptions, equations, and properties of gases derived from kinetic theory. For questions pertaining to rates of reactions, please use the kinetics tag instead.

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Maxwell Boltzmann Curve two peaks

In the image, the second peak appears lower and more plateau-like. What is the chemical reasoning behind this phenomenon? While I understand the relationship between temperature and peak height (with ...
Krishna's user avatar
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-4 votes
0 answers
44 views

Doubt regarding impact of gas on the walls of the container

Assertion :the pressure of a fixed amount of an ideal gas is proportional to its temperature. Reason: frequency of collision and their impact both increases in proportion to square root of temperature....
Nandini's user avatar
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23 views

Is rate of effusion directly proportional to pressure [duplicate]

From Graham's law of effusion we know that rate of effusion is inversely proportional to square root of density of gas but if two gases are being effused at different pressures then is rate directly ...
Shaurya Gupta's user avatar
1 vote
2 answers
125 views

Bubbling air through hydrochloric acid to generate HCl gas

I am trying to build a system to generate dry HCl gas. I was wondering if you bubble air through diluted HCl will it produce a gas with mostly water vapor or HCL vapor, can we vary the proportions of ...
The Entity's user avatar
-4 votes
2 answers
151 views

When a gas is expanded, why doesn't the number of moles of a gas increase despite it's volume increasing? [closed]

This question might be elementary, but it is genuine. I realise that some users might downvote the question for being so basic, but I urge them to be a little merciful, and help out a confused high ...
Bongo Man's user avatar
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-2 votes
1 answer
249 views

Can a heated gas leave a container through downwards direction?

If I have a flask full of heated gas, with an opening at the BOTTOM of the flask and connected pipe facing downwards, can the heated gas can leave the flask through that opening? And for an alternate ...
user137670's user avatar
1 vote
1 answer
130 views

In collision theory why we multiply collision frequency by N/2?

In kinetic theory of gases we know that the average number of collisions, $N_\mathrm{col}$, is given by $$N_\mathrm{col} = \sqrt{2\pi\sigma^2 \overline{v}_\mathrm{rel}}\ N $$ where $N$ is the number ...
World Producer's user avatar
0 votes
1 answer
100 views

Kinetic energy change in reaction

If we consider a reaction occurring at constant pressure and temperature , we know that enthalpy represent the net heat released or absorbed by the system and internal energy accounts for both heat ...
Govind Prajapat's user avatar
6 votes
1 answer
233 views

Non-Arrhenius temperature dependence of bimolecular reaction rates at very high temperatures

Once I have read that in some cases bimolecular reactions can exhibit a maximum as a function of temperature due to the short lifetime of the activated complex at very high temperatures. At low ...
YoussefMabrouk's user avatar
0 votes
1 answer
185 views

RMS Speed of Gases as Standard Deviation

In kinetic molecular theory, the average velocity of gas particle is zero since the molecule move in different directions, and the overall effect is zero. Howeever, you can calculate different speeds. ...
Starlight's user avatar
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1 answer
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Validly of the equation, du= nCv dt, for an adiabatic process [duplicate]

In an adiabatic process, there is no heat exchange, hence, $Q=0$. The equation $\mathrm dU=nC_V\,\mathrm dT$ is valid for every type of process given the gas is ideal, where $C_V$ is heat at constant ...
Maddy's user avatar
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Probability distribution for the momentum of a particle undergoing a collision?

Background I haven't seen this mauver done before but let's say, I have a thermal gas and I have a molecule with momentum $\vec p$. It undergoes a collision and now has momentum $\vec P$. Now, due to ...
More Anonymous's user avatar
3 votes
1 answer
236 views

Is it Rigorous to Derive the Arrhenius Exponential Term from the Boltzmann Distribution?

The Boltzmann distribution is a probability density function which expresses the probability of finding a particle in an energy state $\epsilon$ while in thermal equilibrium given a specific ...
ScientiaNatura's user avatar
1 vote
1 answer
312 views

Why is the isenthalpic condition required in the Joule–Thomson effect?

I have been struggling to understand how the molecules behave during the Joule–Thomson effect. I would love to get some help on this concept. Here is what I got so far. Under adiabatic and isenthalpic ...
asdfasdfasdf's user avatar
-2 votes
1 answer
366 views

Average molecular distance between hydrogen gas [closed]

The whole question goes like this: Calculate the de Broglie wavelength of hydrogen molecule at 300K (Take the translational energy to be 1.5kT) Compare this to the average intermolecular spacing for ...
Sj2704's user avatar
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2 votes
0 answers
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What is the average collision duration?

So I've been trying to figure this out: What is the average collision duration of a gas in terms of macroscopic variables? What I have figured out. Whenever two molecules collide they must reach a ...
More Anonymous's user avatar
0 votes
0 answers
49 views

What ideal gas behavior is observed by a real gas that observes Boyle's law (at Boyle's temperature)?

Boyle's temperature is a constant for a particular gas. At this temperature the real gas behaves ideally. So, does the real gas only follow Boyle's law at this temperature, or are all the gas laws ...
csebks's user avatar
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2 answers
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Why is real volume not smaller than ideal volume in the van der Waals gas equation correction terms? [duplicate]

The following equation is valid for ideal gases $$pV=nRT$$ Please mind the following notation, any parameter that is related to an ideal gas would be denoted with a subscript $i$ and anything related ...
Subhadip Kar's user avatar
8 votes
1 answer
731 views

Confusion in Van der Waals Equation

I understand that the behavior of ideal gases deviates largely from that of real gases in terms of pressure exerted by the gas molecules on the container in which it is present, space available for ...
anotherhyooman's user avatar
1 vote
1 answer
197 views

Question on Thermodynamics from a recently conducted Examination

This is a question from the recently conducted JEE Main exam (in India). I had solved it myself, but found the answer to be incorrect. Here's the question. Here is how I solved it: $\Delta H = \pu{41....
Nilabja's user avatar
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-2 votes
1 answer
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Isolation is a Consequence of Definition [closed]

Let's consider a ballon, such that it has an adiabatic wall, and there is no exchange of heat with the surroundings. Now, let the balloon wall be completely impermeable to the movement of matter ...
Solid - NMR's user avatar
0 votes
1 answer
641 views

Cubic nature of van der Waals' gas equation

$V_m^3-\dfrac{RT+bP}{P}V_m^2+\dfrac{a}{P}V_m-\dfrac{ab}{P}=0$ 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 ...
Akshaj Bansal's user avatar
0 votes
1 answer
146 views

According to Maxwell-Boltzmann distribution, what is probability distribution function proportional to?

If, according to the Maxwell-Boltzmann distribution $${f(v)}\propto\exp\left(-\frac{\varepsilon}{kT}\right),\tag{1}$$ which is the equation from which the whole final equation is derived, then why is ...
theawesomenerd's user avatar
1 vote
1 answer
145 views

Why is the value of $A$, in the expression for Boltzmann's distribution of speeds, not directly calculated?

I've read the proof for the expression for Boltzmann's distribution of speeds on this site. There, $f(v)$ is first factorized into $f(v_x)$, $f(v_y)$ and $f(v_z)$ and $A$ into $A_x$, $A_y$ and $A_z$. ...
theawesomenerd's user avatar
1 vote
1 answer
289 views

If Graham's law doesn't apply to the ammonia and hydrogen chloride diffusion in a glass tube demonstration, is there a law that does?

A comment below What exactly are "white fumes" and why does holding a bottle of ammonia (conc) next to a bottle of HCl (conc) make them? links to The Royal Society Of Chemistry video ...
uhoh's user avatar
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4 votes
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Why does the factor of ⅔ come in when we calculate net flux due to diffusion for an ideal gas

As per Atkins' Physical Chemistry (11E) Pg:694. We arrive at a crude estimate for the net flux through an imaginary flux plane. We find it to be $$J_{z}=-\frac{1}{2}v_{mean}\lambda(\frac{d\mathcal{N}}{...
Uranium238's user avatar
2 votes
1 answer
745 views

Relation between concentration and activation energy

Will increasing the concentration of the reactants in a chemical reaction increase the proportion of molecules with an energy greater than the activation energy $E_\mathrm{a}$? It seems to me that the ...
Greg's user avatar
  • 21
0 votes
1 answer
138 views

What is heat bath here?

At the beginning $\pu{1 mol}$ of air is compressed to $\pu{3 atm}$ at a of temperature $\pu{523 K}$. After a random process, the pressure of the air equates to $\pu{1 bar}$ at a temperature of $\pu{...
Jun Seo-He's user avatar
1 vote
1 answer
161 views

Density gradient vs. entropy of mixing

I was wondering how real gases would behave when they are released into a closed container with fixed volume. For example, suppose we use chlorine and nitrogen gas. Obviously, chlorine has a higher ...
Mäßige's user avatar
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0 votes
1 answer
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Degrees of freedom of a molecule of N atoms [closed]

Apparently a molecule of N atoms has 3N degrees of freedom. How? Shouldn't it be dependent on the structure of the molecule? How exactly do we derive this?
lazearoundallday's user avatar
3 votes
2 answers
2k views

Is air made 100% from atoms?

I know air is made up of roughly 78% nitrogen, 20% oxygen, etc.. but I would like to know what percentage of air is just space and has no atoms at all.
jon's user avatar
  • 163
0 votes
1 answer
240 views

Confusion regarding continuity of state

I was reading about Andrew's isotherms and about the continuity of state. What confused me was the continuous conversion of gaseous state to liquid state. Now my textbook says that by keeping volume ...
Anili's user avatar
  • 79
3 votes
0 answers
847 views

Formula for collision frequency and mean free path

We were studying collision frequency and mean free path today, and in it, we got the equations of collision frequency as: $$Z=\sqrt 2 \pi \sigma^2v_{rms}N$$ where $N$ is the number density, equal to $...
stonecraft bros's user avatar
0 votes
0 answers
83 views

Is the value for the Boltzmann Constant different in 2D?

So I'm simulating some hard sphere collisions and want to determine the Boltzmann constant in two dimension, using the equation $$PA=Nk_BT$$ where $A=\pi R^2_{container}$, $P=(averageImpulse/time)/(2\...
Chern-Simons's user avatar
1 vote
0 answers
195 views

Virial expansion of real gas equation and volume work

Hi I am currently working on a thermodynamics problem, and it asks me to first find the volume work done on a gas that behaves like the simplified Dieterici equation (see below) predicts on isothermal ...
maschine's user avatar
2 votes
0 answers
61 views

Is this a valid interpretation of the Mean relative speed between two (Maxwell-Boltzmann) species?

In textbooks, the collision frequency $Z_{ab}$ is always given as something like: $$Z_{ab} = n_an_b\sigma_{ab} \Bigg(\frac{8 k T}{\pi \mu}\Bigg)^{1/2}= n_an_b\sigma_{ab} \bar{C}_{rel}$$ where the ...
beans's user avatar
  • 21
3 votes
0 answers
198 views

What exactly is a photon gas?

I came upon this question in a JEE Advanced mock test online: The number of photons of wavelength $\lambda$ required to achieve pressure $P$ in an empty cubical box of edge length $l$ is given by $\...
Tatai's user avatar
  • 317
9 votes
3 answers
1k views

Comparing van der Waals constant for gases

How can I compare the van der Waals constant $a$ (the liquefication constant) for different compounds based on my knowledge of bonding in the compound? Let's pick the following sample set: $$ \...
Swadhin's user avatar
  • 307
0 votes
0 answers
58 views

Which formula for kinetic energy of 1 mol of a gas is universally applicable? [duplicate]

I have read 2 formulas for kinetic energy of 1 mol of gas - 3/2 RT and 1/2fRT . But if I equate them then f comes out to be 3 . But f is different of mono, di, polyatomic gases . Where am I wrong in ...
Debodit Ray's user avatar
-2 votes
1 answer
113 views

Graham's Law of Effusion when Looking at Samples with Equal Mass?

So, I had a question on a chemistry test about two gas samples, one of O2 and one of N2, that had equal masses. We were given the time of effusion for the sample of N2 and then asked to calculate the ...
Michael Douglas's user avatar
1 vote
2 answers
2k views

Change in Enthalpy in Free Expansion of Ideal and Real gas against Vacuum

By free expansion, I am referring to gas allowed to expand freely against vacuum in a Joule Expansion. If gas is ideal then change in Internal Energy '∆U' and change in Enthalpy '∆H' is zero. (By ∆H = ...
InfiniteCool23's user avatar
4 votes
1 answer
177 views

Question regarding $Z$ (Compressibility factor)

Oh! This problem has been bugging me for a long time. According to Wikipedia, the Compressibility factor $Z$ is defined as the ratio of the volume occupied by a real gas to the volume occupied by an ...
Indrasen ghosh's user avatar
8 votes
5 answers
2k views

Is the average kinetic energy of evaporating water molecules (at room temperature) equivalent to the average kinetic energy of boiling water?

Purpose: On new year's eve, after a splendid red and an assortment of sumptuous repasts, I made a bold remark which, on further consideration, may turn out to be incorrect. Unless! Unless I can ...
Jeff's user avatar
  • 83
-1 votes
2 answers
533 views

Why are some liquids hotter than room temperature gases if liquid and solid molecules move more slowly than gases? [closed]

We learned in school that state change is a matter of molecules moving faster and faster. And we learned "heat em up, speed em up, spread em out". Why then can some liquids have higher ...
suse's user avatar
  • 803
-1 votes
2 answers
2k views

Under what conditions does Real Gases show Ideal Behaviour? [closed]

MY textbook says : Real gases show Ideal Behavior under low pressure ,high temperature. So I wanted to know what happens to real gases at high pressure ,low pressure Do they also show ideal behavior ...
Universe A7's user avatar
1 vote
1 answer
239 views

Ideal gas equation derivation proportionality [duplicate]

While deriving the Ideal gas Equation using Boyle's, Charles', and Avogadro Laws, how are each of the laws, which have different proportionality constants and different quantities as constant combined?...
Chem's user avatar
  • 19
1 vote
1 answer
1k views

What gas law is involved when your ears "pop" when you are on a plane high in the air? [closed]

When you are up in the air, the air pressure decreases and the altitude increases. What gas law is involved in the situation wherein your ears "pop" because of the difference in pressure.
John smith's user avatar
1 vote
1 answer
810 views

Adiabatic expansion of gas

If a real gas is adiabatically expanded against constant pressure, then which of the following will definitely increase? Compressibility factor (Z) or Entropy (S) Correct answer: Entropy My answer: ...
Shaurya Goyal's user avatar
-1 votes
1 answer
171 views

Maxwell's distribution function for mixture of ideal gases

I came across a question demanding relations between the individual distribution functions $f_n$ for the $n$th gas, and the overall $f$ for the entire mixture. I believe there is no simple way to ...
Thenard Rinmann's user avatar
4 votes
1 answer
227 views

Rigorous reason behind internal energy change being zero while mixing

A container is divided in two parts: one part contains oxygen gas $(n_1$ moles, at temperature $T_1)$ and the other part contains helium gas $(n_2$ moles, at temperature $T_2).$ The partition ...
satan 29's user avatar
  • 379