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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What is the formula for the rate of evaporation of methanol? [closed]

I want to increase the rate of evaporation of methanol by sucking off its vapour as it evaporates. Is it possible and can we mathematically show it? Also I want to produce a refrigeration effect so I ...
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Effect of pressure on viscosity of liquids and gases [closed]

My textbook says the following on viscosity and pressure: increase in pressure decreases the viscosity of water but for other liquids it increases. Viscosity of gases does not change much No ...
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510 views

According to KMT, is the velocity of an ideal gas always sqrt(3RT/M)?

It is a common textbook question to treat the root mean square velocities of an ideal gas as given by the following equation: $$v_{rms}=\sqrt{\frac{3RT}{M}}$$ I was wondering about the validity of ...
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Why does water vapour deviate much more from ideal gas behaviour as it is cooled compared to nitrogen gas?

My guess is that it is something to do with the difference in boiling point between the two aforementioned molecules. But I can seem to come up with a logical explanation to why this is the case.
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Comparing rates of effusion between species

I'm struggling with (i) and (ii). I understand how to do (iii) and (iv) as it is just an application of Graham's Law of Effusion twice and n times (solve for n) respectively. I am starting with rate ...
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Is kinetic energy proportional to temperature for non-gases?

If the molecules in a sample of ice at $\pu{-15 °C}$ and $\pu{1 bar}$ all have their kinetic energy doubled, then what is the final phase? The answer is gas, but I am not sure how to get this answer. ...
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26 views

How does the temperature affect the frequency factor?

I am a high school student and have been trying to learn how the temperature affects the frequency factor. I did not even understand the equation below, which is from this site. Can anyone please ...
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54 views

Determining heat capacity of gasses

I need a little help on answering a question which popped into my head while I was reading about gas laws: Suppose that I have three canisters, each holding a different gas of unknown identity [...
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45 views

Validity of Maxwell-Boltzmann distribution for solids [duplicate]

Suppose there is a solid made of avogadro number of, say, aluminium atoms. This solid is kept at 273 K. According to Maxwell-Boltzmann distribution, all the particles or atoms will not have the same ...
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53 views

Is it possible to use the laws of termodynamics for non-ideal systems?

For the reaction $$\ce{2CO(g) + O2(g) -> 2CO2(g)}\quad\Delta H = \pu{−560 kJ}$$ it is given that the reaction occurs at constant volume of $\pu{1L}$ and the initial and final pressures are $\pu{...
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Kinetic Diameter: How to calculate it? Pressure influence?

Wikipedia states: Kinetic diameter is a measure applied to atoms and molecules that expresses the likelihood that a molecule in a gas will collide with another molecule. It is an indication of the ...
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What gas would be suited best to form a density gradient in a long tube? [closed]

I want to set up an aero-optics experiment using a sealed ~5 m length of pipe with a gas inside. The gas must form a density gradient, and must be transparent enough to view a target at the other end ...
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436 views

Is oxygen above the critical point always supercritical fluid? Would it still appear to roughly follow the ideal gas law?

In this answer I've asserted (without a "Chemist's license") that as long as oxygen is above it's critical point in both temperature (154.5 K) and pressure (50.4 bar) it's going to be a supercritical ...
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Can someone walk me through this gas mixture question?

Argon $(\ce{Ar})$ and helium $(\ce{He})$ are initially in separate compartments of a container at $\pu{25 °C}.$ The $\ce{Ar}$ in compartment A which has a volume $V_\ce{A}$ of $\pu{9.00 L}$ and a ...
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1answer
85 views

What happens when a super-critical fluid is compressed?

Suppose that I have some substance with a critical temperature of 20°C. That means above that temperature, the substance exists neither as a gas nor a liquid, but instead as a super-critical fluid. ...
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1answer
118 views

Why is the rate inversely proportional to the square root of temperature in Grahams Law of Diffusion?

In my book it is given that: The general form of the Grahams Law of Diffusion can be stated as follows when one or all of the parameters are varied: $$\text{rate} \propto \frac{PA}{\sqrt{TM}},$$ ...
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179 views

How to find the temperature relationship between the isotherms in a compressibility factor (Z) vs pressure graph?

The following graph denotes the variation of the compressibility factor (Z) with pressure at different temperatures for a real gas. Simply each of the curves represents an isotherm. Now, suppose we ...
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370 views

Volume of a gas

The kinetic theory assumes that, for an ideal gas, the volume taken up by the molecules themselves is entirely negligible compared with the volume of the container. For a real gas, that assumption isn'...
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What are the limitations of the Theorem of Corresponding states?

I recently came across the theorem of corresponding states, which states that all gases exhibit the same compressibility factor, under same reduced pressure and temperature (and also the critical ...
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223 views

How to derive the compressibility factor for a van der Waals gas?

So as far as I know, $$Z=\frac{p_\mathrm{r}V_\mathrm{r}}{nRT},$$ where $\mathrm{r}$ denotes the subscript for real. Solving it for a van der Waals gas gave me the following result, $$Z=1+\frac{p_\...
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Compressibility Factor Of Gases

In the general equation of the compressibility factor $Z$, we define $Z$ as $$Z=\frac{pV}{nRT}$$ Here, what is $p$? Is it $p_\text{real}$ or $p_\text{ideal}$? Also, what is $V$? $V_\text{real}$ or $V_\...
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112 views

What happens to the pressure of gas when only one molecule of it is placed in a very large container?

We say that pressure due to gas is constant throughout the container. Pressure is created by molecules present in it. When there are many molecules I agree that they can apply the same pressure all ...
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1answer
63 views

The distance that CO2 molecules travel in the air before they collide with each other

Well the title covers most. But further at 410 ppm, 1 atm and 23 °C. I believe they call it the mean free path of CO2-CO2 collisions. So not just the mean free path of CO2 in air colliding with every ...
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1answer
322 views

Why 1 mole of H2 occupied the same volume occupied by 1 mole of O2?

I'm asking a question about the volume occupied by gasses in standard temperature and pressure. My textbook said that a mole of any gas occupies 22.4 L at standard temperature and pressure. But ...
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Finding Pressure of M in a Charge Exchange

Ar (RE = 15.5 eV) is the reagent gas in a charge exchange experiment. If Ar+ reacts with anisole with a rate constant of 2.26x10-10cm3 molecules-1/s-1 and 65% of the Ar ions react in 25 milliseconds, ...
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844 views

The respective speed of five molecules are 2, 1.5, 1.6, 1.6 and 1.2 km/s. The most probable speed in km/s will be?

The respective speed of five molecules are 2, 1.5, 1.6, 1.6 and 1.2 km/s. The most probable speed in km/s will be? 1. 2 2. 1.58 3. 1.6 4. 1.31 I think the answer should be 1.6 km/h but the ...
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1answer
75 views

What is the radius of the atoms? [closed]

In a recipient there is an unknown monoatomic gas that occupies a volume of $\pu{230 cm3}$, at $\pu{300 K}$ and $\pu{1 atm}$. It is known that the atoms occupy a volume of $2\times10^{-4}$. Find the ...
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1answer
46 views

Shape of the container and the number of possible energy states

A question came up when studying the formula for calculating the total number of possible energy states of a particle within a container. Why is the number of possible energy states independent of ...
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Feasibility of application of Boyle's law in the case of varying number of moles [closed]

While reading up on ideal gases and the Boyle's law, I encountered a question in my textbook wherein a balloon was being filled with helium (assumed to be ideal) till it was just about to burst. The ...
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66 views

How does degree of freedom work [closed]

I understand that the degree of freedom is the number of ways in which a molecule can acquire energy. I don't want you to explain the definition, but I want to see how it works. Please explain how is ...
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3answers
673 views

Equalization of pressure in heat exchanger

I was solving numericals on Kinetic Theory of Gases when I came across this question Two closed vessel of equal volume contain air at 105 kPa, 300 K and are connected through narrow tube. If one of ...
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1answer
383 views

Does the translational part of internal energy mean the kinetic energy of the gas?

Internal energy of an ideal gas consists of energy due to translational, rotational , vibrational etc. This line from WP says: In thermodynamics, the internal energy of a system is the energy ...
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1answer
214 views

Why do gases coexist as liquid and vapour?

I have having difficulty in understanding the liquefaction of gases.In the graph of isotherms of $\ce{CO2}$ I cannot understand how can gas coexist as liquid and vapour under area of $\mathrm{XCEBY}$....
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1answer
51 views

Why are moles used in the ideal gas law and not simply mass?

The crux of my question is, why is just the amount of particles included in $PV=nRT$ and there is nothing to account for the mass of the individual molecules? Or is mass accounted for in temperature, ...
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286 views

Interpreting straight lines in a graph of isotherms of carbon dioxide

I am having difficulty in understanding pressure-volume graphs of $\ce{CO2}$ at different temperatures which describes liquefaction of $\ce{CO2}$. I know that at the critical temperature of $\pu{31.1^...
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3answers
1k views

What is the term used as correction for attractive forces in the Van der Waals Equation?

I have seen a question in my textbook which is little bit confusing, The term that corrects for attractive forces present in real gas in van der Waal equation is (i) ${nb}$ (ii) $\frac{an^2}...
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1answer
234 views

Dependency of rate of diffusion on mean free path and velocity of molecules? [duplicate]

What is the dependency of rate of diffusion ( Graham's law) on mean free path, molecular size , average velocity, collision frequency and pressure? I have searched everywhere on internet but just ...
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48 views

How was it possible to accurately measure the mass of gases in the 19th century?

I have seen periodic tables of Mendeleev (1834-1907) and Newland (1837-1898) in which masses of gases such as oxygen and nitrogen were shown. I don't think there were instruments to measure mass of ...
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77 views

Is there a better model than the Kinetic Theory of Gases [closed]

I'm looking for a better relationship between the Kinetic energy of a gas and it's Temperature, and also how they vary with gravity (not altitude, just gravity!). So is there a model better than the ...
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194 views

Finite probability from discrete distribution and zero probability from continuous distribution in Maxwell-Boltzmann statistics

I have difficulty understanding a certain concept with the derivation of the Maxwell-Boltzmann distribution $f(v)$ function from Boltzmann statistics. The derivation starts with the Boltzmann ...
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1answer
74 views

Does the probability function for a molecule to have energy in a certain mode depend on the minimum required quantum energy level of that mode?

I understand that the probability density for a particular velocity v+dv in one dimension for a molecule in a system is: $$f(v) = \sqrt{\frac{m}{2\pi k_B T}} \cdot e^{\frac{-mv^2}{2k_B T}}$$ I'm ...
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108 views

Effusion rate 1.4 times faster SO2(g)

How do I solve this- Which diatomic gas would effuse at a rate that is 1.4 times faster than the rate at which so2(g) effuses at any given temperature? This is high school chemistry. I did: (using ...
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1answer
269 views

van der Waals equation for deviation of gases from ideal behavior

$(P + an^2/V^2)(V - nb) = nRT$ I understand that the term $nb$ is subtracted from the volume term as the available volume for the gas molecules to move around decreases in the case of a real gas ...
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Volume of gas in containers

If gases occupy all the volume in a container then how can we define 'volume percent' as all different gases will have same volume?
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What is the relation between absolute temperature, and rates of diffusion and effusion of a gas?

According to Graham's diffusion law, rate of diffusion is directly proportional to square root of temperature but rate of effusion is inversely proportional to square root of temperature. Why is this ...
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264 views

Effect on rate of diffusion in addition of an inert gas

What will be the effect on the rate of diffusion on addition of an inert gas to the gaseous mixture? I think the rate of diffusion should increase as the addition of extra gas will increase the ...
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50 views

Is the kinetic gas equation valid for non-cubical containers?

I have seen the derivation of the following equation for a cubical container with $N$ molecules. $$PV = \frac 13 mNu^2 $$ How is this equation valid even for spherical container or any other non ...
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147 views

Why is the speed of ideal gases mass dependent while the kinetic energy is not?

The rms speed of an ideal gas is $v_{\text{rms}}$ = $\sqrt{\frac{3RT}{M} }$ and the kinetic energy is $E_\text{k} = \frac32RT$. From this, it is concluded that the speed is mass dependent, while the ...
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57 views

How to determine if pressure surpasses capacity with the van der Waals equation of state?

I have to decide whether a $\pu{20 L}$ container with $\pu{0.8 kg}$ ethane can withstand the pressure at $\pu{373.15 K}$. The following information is given: \begin{align} b &= \pu{6.448x10^-2 ...
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Is Internal Energy = (3/2)nRT for a ideal monoatomic gas?

Internal Energy is a state variable and its value at a particular state cannot be measured; only the change in internal energy can be measured. So how come we write that $$U=\frac32nRT$$ where $U$ = ...