Questions tagged [ideal-gas]

For questions about the ideal gas law or gases which can be well approximated as an ideal gas.

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Finding porosity using Ideal gas law

A 1 $cm^3$ sample or reservoir rock is put in a chamber of 10 $cm^3$, where the total pressure is 750 $mmHg$. This chamber is closed, and a valve is opened such that the air can expand to another ...
67 views

Phase diagram for a mixture of substances

I have a rudimentary question about phase diagrams, my professional training is as a mechanical engineer so I don't deal with them often. I have an experiment where I need a mixture of air and CO$_2$ ...
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Question about chemical potential of a multicomponent ideal gas

Consider a pure ideal gas, i.e. only having one component. The chemical potential and free energy of this gas are as follows: $$\mu_1=\mu^\circ(T)+RT\ln\left(P\right)$$ $$G_1=n\mu_1$$ Where n is the ...
71 views

Volume of gas mixture [closed]

I have inlet to a reactor formed by equimolar CH4 and NH3, I want to find the volume of this gas mixture. First I wanted to calculate the sum of individual volumetric flow rates from V = m*rho. ...
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 ...
84 views

Volumetric flow rate ratio calculation

I'm using two tanks of nitrogen and oxygen and mixing them in different ratios to change the oxygen partial pressure in the system. System is opened to the atmosphere through the venting pipe which ...
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How to convert molar volume to volume?

This seems like a simple question that people must have asked already, but I can't find an answer online. I'm not a chemist, but need to use a code that deals with thermodynamics. I am trying to use ...
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1 vote
54 views

Deviation from ideal gas behavior

I know that gases deviate from ideal behavior at low temperature and high pressure But what if we increase the pressure of a gas by increasing the temperature keeping the volume constant. Would the ...
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Is gas solubility independent of pressure?

My physical chemistry textbook poses this question: Prove the statement that an alternative way to express Henry’s law of gas solubility is to say that the volume of gas that dissolves in a fixed ...
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212 views

How can enthalpy of an ideal gas be independent of pressure?

I know that when one applies a manipulation of the Ideal Gas Law to the Maxwell Relations the result that enthalpy is independent of pressure tumbles out of it, i.e., $(\mathrm dH/\mathrm dp)=0$. I ...
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159 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 ...
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50 views

Validity of ideal gas law for pure species or mixture

I'm currently dealing with an application involving gases. I have pure nitrogen as a pressurizer and eventually water vapour (only if condition for evaporation or boiling are met). I wanted to ask to ...
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1 vote
247 views

How do I determine temperature and pressure rise whenever mols of gases are added in a isolated room?

Let's consider a fully isolated room, no gas or heat flowing from it. We consider gases ($\ce{O2,N2,CO2}$) to follow the ideal gas law, and no chemical reaction occurs between them. Pressure $p$, ...
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1 vote
135 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 ...
205 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. ...
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How do alpha particles contribute to pressure of nuclear decay products?

A closed vessel with rigid walls contains 1 mol of $_{92}\ce{U}^{238}$ and 1 mol of air at 298K. Considering complete decay of uranium to $_{82}\ce{Pb}^{206}$, the ratio of final pressure to initial ...
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Is the change ΔG for an ideal gas unknown?

When one is introduced to the first law of thermodynamics, one learns that enthalpy is only a function of temperature, and calculating its changes is straightforward \Delta H^\pu{...
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According to PV=nRT,if we increase temp,no of moles will decrease,but no of moles is dependent on mass,mass is constant,then how can moles change?

We know the ideal gas equation is PV=nRT,then, according to this,if we keep Pressure,volume to be constant,then on increasing temperature,no of moles will reduce,this would mean that mass of matter or ...
1 vote
125 views

How do I go about calculating final temperature of tank draining at saturation?

I am working on calculating pressure in a tank where the fluid is sitting at its vapor pressure. For example, imagine a 12 in diameter 100 L tank of nitrous oxide at room temperature (745 psi vapor ...
66 views

How can Joule-Thomson inversion coefficient of ideal gas be zero? Does temperature of ideal gas not change on adiabatic expansion?

Does Joule-Thomson coefficient being zero means there will be no change in temperature? If that is the case then according to first law of thermodynamics, E = Q+W (don't know how to add delta sign). ...
64 views

Calculating percentage of Zn in a coin

Question: An old coin found in an ancient temple is composed of zinc coated with copper. In an experiment to find the percent zinc in the coin, a student determined the weight of the coin to be 3.0 g. ...
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495 views

How exactly does Boyle's law, Charles' law, and Avogadro's law combine to make the Ideal Gas Law?

My General Chemistry 1 lecturer derived the ideal gas law as follows: We have $V \propto \frac1{P}$ (Boyle's law), $V \propto T$ (Charles' law), and $V \propto n$ (Avogadro's law). Combining these ...
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76 views

Identify two hydrocarbons using volume and density [closed]

Question: A gaseous mixture with volume 16.8 dm3 contains two unsaturated neighboring hydrocarbons belonging to the same group. Density of the mixture was 14.4 times as hydrogen gas. What could be ...
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304 views

Find percentage of carbon monoxide reacted using ideal gas equation

Question A palladium or platinum catalyst was used in an automobile to convert carbon monoxide gas to carbon dioxide according to the following reaction: $$\ce{2CO(g) + O2(g) -> 2CO2(g)}$$ A ...
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370 views

My experiemental density of H2 does not match the published data. What causes this discrpenecy?

I placed 1 gram of NaBH4 in a balloon and placed it over a glass round bottle filled with water and acetic acid. While secured, I emptied the balloon into the bottle and made sure to wash the inside ...
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Dalton's law clarification

I'm looking at Elements of Physical Chemistry by Atkins and de Paula. In section 1A.3, they state Dalton's law as The pressure exerted by a mixture of perfect gases is the sum of the pressures that ...
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174 views

How to define percentage by volume for ideal gas and Why percentage by volume is equal to percentage by mole? [closed]

Why do we define percentage by volume for an ideal gas in a closed container in spite of that we know the ideal gas will occupy the volume of the whole container? I have seen many people who prove ...
106 views

What is the Volume occupied by gas at extreme or limiting conditions of volume? [closed]

We know that 1 Mole of an Ideal Gas occupies 22.4 L at STP. [real gases also are also close to this volume , even tho there might be deviation, for this experiment let's take both to be same] But it'...
1 vote
132 views

Henry’s Law Pressure Limitations

I’m trying to decide if I can I expect Henry’s Law to be an effective way to estimate how the solubility of a gas in a liquid solution will change if I decrease the pressure. I know Henry’s is best ...
273 views

Can we calculate final temperature of two gases in thermal contact? [closed]

This is a question from IIT-JEE - ADVANCE 2018 A closed tank has two compartments A and B, both filled with oxygen (assumed to be ideal gas). The partition separating the two compartments is fixed ...
752 views

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 ...
1 vote
141 views

Use the first law of thermodynamics to derive the pressure as a function of T, U, V and N

I am struggling with a thermodynamics question given $$S(U,V,N)=C_VNK_\mathrm b\ln U/U_0+NK_\mathrm b\ln V/V_0$$ (where $U_0$ and $V_0$ are the reference energies and volumes) and the first law of ...
297 views

Molecular collisions in an ideal gas

(The equation of ideal gas is $pV=NRT$. If p = 1 atm, N = 1 mole, T = 0°K, and R = gas constant, then volume = V = zero. Hence, the volume of an individual molecule of ideal gas is zero). An ...
756 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 ...
428 views

Gibbs Free Energy of Ideal Gas in Carnot Cycle

Let's just say we have 2 moles of monoatomic (maybe helium) ideal gas that is doing a Carnot Cycle with reservoir temperature of 300 and 750 K. Now, here's a simple question, what is the Gibb Free ...
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1 vote
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What is the necessary and sufficient condition for a mixture to be ideal?

I am trying to understand some concepts from solution thermodynamics related to ideal mixtures and fugacity. My main question is what is the necessary and sufficient condition for a mixture to be an ...
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How do I calculate the temperature change in a gaseous reaction?

So, with $\pu{3 mol}$ of $\ce{H2}$ and $\pu{3 mol}$ of $\ce{Cl2}$ and given the reaction $\ce{H2(g) + Cl2(g) -> 2 HCl(g)}$ with $\Delta H=\pu{-184.6 kJ/mol}$, I am supposed to calculate the work ...
1 vote
295 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 ...
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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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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 $$J_{z}=-\frac{1}{2}v_{mean}\lambda(\frac{d\mathcal{N}}{... 0 votes 0 answers 262 views Energy change of isentropic expansion of ideal gas I'm trying to get a better grasp on dealing with different processes thermodynamic, and this one is giving me trouble. The differential of energy is given by$$dU= \delta Q + \delta W~.$$I'm ... • 93 1 vote 0 answers 229 views Why 3 and not 6 in U = 3/2RT from the equation for the internal energy of an ideal gas? Internal energy of an ideal monatomic gas is$$U=\frac{3}{2}RT.\tag{1}$$While I understand the derivation, I do not understand why we multiply by 3 rather than by 6. According to Khan Academy ... • 11 3 votes 0 answers 901 views Formula for collision frequency and mean free path We were studying collision frequency and mean free path today, and in it, we got the equations of collision frequency as:$$Z=\sqrt 2 \pi \sigma^2v_{rms}N$$where N is the number density, equal to ... 0 votes 0 answers 85 views Is the value for the Boltzmann Constant different in 2D? So I'm simulating some hard sphere collisions and want to determine the Boltzmann constant in two dimension, using the equation$$PA=Nk_BT$$where A=\pi R^2_{container}, P=(averageImpulse/time)/(2\... • 139 1 vote 1 answer 126 views What happens when V=Nb in the Van der Waals equation (divergent)? The VdW equation:$$\left(P+a\left(\frac{N^2}{V^2}\right) \right)\left(V-Nb\right)=Nk_BT$$when the intermolecular forces are zero a=0, so P=\frac{Nk_BT}{V-Nb} which diverges at V=Nb for fixed ... • 139 2 votes 1 answer 553 views Relation of temperature to effusion and diffusion [duplicate] We were studying Graham's Law today and its dependence on Temperature, Pressure, Area, etc. However, our teacher said that, for diffusion:$$R \propto \sqrt T$$and for effusion:$$R\propto1/\sqrt T ...
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 \$\...