Questions tagged [gas-laws]

Physical and chemical laws describing the properties and behavior of gases. This tag currently applies to properties and laws concerning both ideal and real gases.

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Why is the value of the heat capacity ratio γ the same for molecules with the same atomicity?

The heat capacity ratio is defined as the ratio of the heat capacities at constant pressure and volume respectively: $$\gamma = \frac {C_p}{C_V}\tag{1}$$ Then obviously $$\gamma = \frac{n\,C_p\,\Delta ...
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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 ...
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Can general purpose compressors be used for a specific gas without modification?

Air compressors are commonly used for all sorts of purposes related to compressing air above 1 atm. My question is, could an air compressor be used for a specific gas without modification? For example,...
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Why should the cubic equation in volume, obtained from Van Der Waals equation of state, have equal roots at the critical point?

The video Edmerls — Derive Equation for Critical Constants in terms of Vander Waal's Constants. | Physical Chemistry (YouTube) provides a derivation of the relationship between the van der Waals ...
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Balanced reaction to Cr given H+ [closed]

The troublesome nature of this post, is that I was given very little information to work with: "The metal chromium (Cr) reacts with an acid, to create Cr^+3 ions, and hydrogen gas. Show the ...
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Stratification of gasses by mass [closed]

Suppose a homogenous mixture of mutually non-reactive gases is isolated in a container so that there are no external kinetic forces (vibration or rotation) that create turbulence or other mixing ...
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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 ...
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How to prepare standard sample of benzene for gas sampling bag?

I need to make a 1 ppm gaseous standard of benzene in nitrogen gas within a Tedlar® gas sampling bag. Is this as simple as injecting 1 μL of neat benzene liquid into 1 L of nitrogen gas within the bag?...
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Why is Molar Mass of a gas twice the vapour density?

I've seen this relation at a number of places, and I can't get why. A simple Google search doesn't give me a simple answer either. Also, are there any exceptions/conditions for this relation to be ...
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What will happen in the volume occupied capacity of each gas when separator is removed? [closed]

Consider a situation where two gases occupying volumes $V_1$ and $V_2$ and having partial pressures $p_1$ and $p_2$, respectively, are kept separated in a rigid container. If the separator is removed, ...
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How to identify isochoric process from the problem's wording?

Problem 19 from NEET's Solved Paper 2013: The amount of heat energy required to raise the temperature of $\pu{1 g}$ of helium at NTP from $T_1$ to $T_2$ (in kelvin) is \begin{align} &\text{(a)}~\...
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Why are certain gases with higher molar masses less dense than the ones that have a lower one?

Neon, despite having a larger molar mass than nitrogen, oxygen and fluorine, is less dense than all of them. This also goes that fluorine (again) and chlorine are both denser than argon, even though ...
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Could an LPG gas ever become lighter than air?

Both of the LPG gases, propane ($\ce{C3H8}$) and butane ($\ce{C4H10}$) are heavier than air. Propane is $1.55$ times heavier and butane is $2.08$ times heavier. Is same-temperature air always lighter ...
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If a = 0 for a Van der Waals gas, what does that signify?

I know that if $a = 0$ for a gas at certain temperature and pressure, it means that the molecules of gas have almost no attractive forces acting between them. But does that also mean that the ...
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Can the expression be represented as a total differential?

I should determine whether the following expression represents a total differential: $$\mathrm{d}f(x,y) = (\ln y) \,\mathrm{d}x + \frac{x}{y}\,\mathrm{d}y$$ But with the following method (physical ...
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Can a vacuum on a closed system really “pull” things out of it?

So I’m learning gas discharge tube making (neon) and there’s a step where you cork one end of the tube and pull a vacuum on the other end to suck out all the impurities. The same thing was done when I ...
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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 $...
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Is it appropriate to say "solid-in-gas solution" and "liquid-in-gas solution"?

A number of books mention "solid-in-gas" and "liquid-in-gas" types of gaseous solutions. However, for something to dissolve in a gas, it must be in its vapour phase. So, for ...
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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\...
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What is reversible change for ideal gas?

What are the reversible and irreversible changes for an ideal gas? Is it the change that keeps the ideal gas law during the change? Is any reversible change a sum of changes satisfying the ideal gas ...
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why can water heated to a certain temperature in microwave explode when removing cup , bowl etc to room temperature air? [closed]

Studied a lot about $\mathrm{pH}$ , molecule dipoles properties $\ce{H2O}$. never saw anything along lines of energy storage, except ice contains heat energy , ionization of water always happens. ...
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Relationship of oxygen dissolved in water with bubble time and temperature

I'm using the Winkler method to calculate oxygen dissolved in water. This is at the temperatures 20, 30, 40, and $\pu{50 ^\circ{}C}$ and I bubbled a controlled amount of oxygen in through the reaction ...
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Method of cooling a gas without liquid evaporation for Sci-fi novel

sorry for the amateur question here. I know little about science, but regardless am writing a fictional amateur novel that deals with a lot of chemistry stuff, especially gasses. My protagonist needs ...
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Dissociation of phosphorus pentachloride in gas syringe

Phosphorus pentachloride is introduced into an empty gas syringe which has a movable, tightly-f‌itting plunger. The gas is allowed to expand until equilibrium is reached at a temperature at which the ...
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Do benzene and hexane form an ideal solution?

My teacher said that benzene and hexane do not form an ideal solution (with reference to Raoult's law) but did not explain any reason for it. My approach: Cyclic hydrocarbons (benzene here) have ...
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Pressure increase in a chamber with 1 ml of water heated to 200 °C [closed]

For safety reasons I want to know how much pressure will be generated in a sealed chamber with $1~\mathrm{ml}$ of water, pure nitrogen at $1.3~\mathrm{bar}$ at $22~\mathrm{^\circ C}$. This chamber ...
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How can I calculate the density of a gas mixture using the ideal gas?

I am trying to calculate the density of the ideal gas mixture given the following data: The gases are helium and oxygen. There are $\pu{8 g}$ $\ce{He}$ and $\pu{16 g}$ $\ce{O2}$. The temperature is $\...
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How does change in temperature affect experimental calculation of molar mass

This is coming from AP Chemistry 2009 q2 f. To sum it up, a student undercalculates the molar mass of a gas that is flushed into a sealed flask of dry air using DRT/P, and you have to justify if the ...
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What gas particles are formed when diamond turns to gas?

If you heat up diamond away from oxygen (air completely) until the solid diamond is now gaseous, what are the gas particles made of? Just the element carbon without a charge?
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Reversible compression and proving relation with state function

I am currently working on a question I am having problems with. I tried to solve it, but to no avail; it states that this expression is always valid for any three-variable dependent function: It ...
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Is there a way to put helium or any other gas into food?

Kinda like pop rocks puts bubbles of carbon dioxide gas into their candy to make it pop, If someone put bubbles of helium into some sort of food light enough then would it float? And how do they even ...
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An atom moving at its root-mean-square speed at 20 °C has a wavelength of 32.8 pm. Identify the atom

An atom moving at its root-mean-square speed at $\pu{20 °C}$ has a wavelength of $\pu{3.28E-11 m}$. Identify the atom. Here's what I did: $$u_\mathrm{rms} = \sqrt{\frac{3RT}{M}}$$ and $$ \lambda = \...
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How do I find the volume of a gas when the pressure and temperature changes, given the original volume? [closed]

I am a sophomore in high school, just started honors chemistry this year, and I'm having trouble figuring out what formula to use for this question, and how exactly to do so: If a gas has an original ...
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1 vote
3 answers
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Does the amount of a gas increase with pressure? [closed]

The graph of $pV/(RT)$ shows that different gases deviate differently from ideal gas behaviour and that the value of $pV/(RT)$ changes as pressure increases. My question is, if $pV/(RT) = n$ or amount ...
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Is a/b > 1 mol/L for a and b in the van der Waals equation?

We know that the van der Waals equation for real gases is $$\left(p + \frac{an^2}{V^2}\right)(V-nb) = nRT.$$ Is $a > b$ always in this equation? In my textbook $a > b$ for gases like $\ce{He},$ $...
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PV=constant and V/T=constant then why PT is not constant? [closed]

We know that P1V1=P2V2 by Boyle's Law. Let's say this equation (i). And we know that V1/T1=V2/T2 by Charle's Law. Let this equation be (ii). Dividing (i)/(ii), we get P1T1=P2T2... But it's completely ...
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Doubts regarding Mole concept and Avogadros number [closed]

So I am really confused about simple topics like mole and Avogadro Here is my oversimplified view So mass of 1 atom of elements in grams was not in whole numbers and it was difficult using em for ...
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About Real Gas and Ideal Gas - Select the correct statement(s):

Select the correct statement(s): At Boyle's temperature a real gas behaves like an ideal gas at low pressure. Above critical conditions, a real gas behaves like an ideal gas. At high pressure van der ...
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Can different components show different deviations from Raoult's law?

Introduction: Raoult's law is used to calculate the partial pressures of the vapour phases of volatile components of a solution Given that there are two components, A and B, in the liquid-liquid ...
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8 votes
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If something is not hydrophilic, is it necessarily hydrophobic?

Is it possible to create hydrophobic water? Two species are phobic within some medium under some conditions when they don't here together (cohere if they're the same species; adhere otherwise). To be ...
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3 votes
2 answers
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Why does van der Waals' equation of state give only one P, V pair for a particular temperature here?

I came across this question which I initially ignored believing that the data was insufficient: Calculate the pressure exerted by one mole of $\ce{CO2}$ gas at $\pu{273 K}$ if the van der Waals' ...
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Effect of inert gas blanket on oxygen solubilized in wine

If applied to a volume of wine, could a blanket of argon become dense enough to remove oxygen from the wine? This is not a question of sparging the wine. Rather, could a blanket of argon over the top ...
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What unit and dimension for membrane permeability / permeation expression?

Context When studying the diffusion of gases through thin membrane, one may use the diffusion coefficient $D$ used in Fick's laws as (one dimension form): \begin{equation} J = - D \cdot\frac{d\varphi}{...
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How to calculate Kp without knowing the volume? [closed]

I have the following chemical equation: $$\ce{Sb2S3 + 3H2 <=> 2 Sb + 3H2S}$$ I have $\pu{1000 grams}$ of $\ce{Sb2S3}$ that reacts with $\pu{10 grams}$ of $\ce{H2}$ in a reactor at $\pu{713 K}$. ...
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What are chemicals that will create a similar reaction to baking soda and vinegar for my book?

I'm writing a book based on a dream I had, but after some research I can't find too much on a specific reaction I want. The main character mixes a clear liquid and yellow powder which hisses and ...
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When do repulsive forces in a gas actually become dominant?

We say that repulsive forces become dominant when Z>1 (i.e. Vobserved > Vtheoretical). But when the difference between Vobserved and Vtheoretical is less than b, shouldn't attractive forces ...
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Does the critical temperature of a gas depend on the amount of the gas taken?

Does the critical temperature of a gas depend on the amount of the gas taken? Or is it independent of it? My book does not specify this point. I think according to the gas laws, the critical ...
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Pressure of two flasks connected to each other at different temperatures [closed]

Two flasks of equal volume connected by a narrow tube (of negligible volume) are at $\pu{27 °C}$ and contain $\pu{0.7 mol}$ of $\ce{H2}$ at $\pu{0.5 atm}$. If one of the flasks is then immersed into a ...
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9 votes
3 answers
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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: $$ \...
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Dissolution of CO2 in water

The following question has troubled me for a while. For gases that are slightly soluble in water, there is a proportional relationship between the partial pressure, $P$, and the mole fraction, $x$, ...
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