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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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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 ...
bloodybutunbowed0's user avatar
-3 votes
2 answers
62 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. ...
Laman Alipashayeva's user avatar
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0 answers
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
0 votes
1 answer
70 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 ...
Dario Mirić's user avatar
-2 votes
1 answer
88 views

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 ...
Ant's user avatar
  • 131
1 vote
0 answers
53 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 ...
Spluesh's user avatar
  • 83
3 votes
2 answers
106 views

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 ...
GMoss's user avatar
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0 votes
1 answer
162 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 ...
MattGeo's user avatar
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-4 votes
2 answers
147 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
  • 369
2 votes
0 answers
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 ...
Enrico's user avatar
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1 vote
4 answers
244 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 $p$, ...
Aya's user avatar
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1 vote
1 answer
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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
176 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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6 votes
1 answer
365 views

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 ...
AVS's user avatar
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2 votes
0 answers
111 views

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 \begin{equation} \Delta H^\pu{...
Metal Storm's user avatar
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11 votes
2 answers
1k views

Why would there be a non-zero Gibbs energy of mixing for ideal gases?

When two ideal gases $\ce{A}$ and $\ce{B}$ mix, they don't interact. The chemical potential of each gas is independent of the other, e.g. for $\ce{A}$: $$\mu_\ce{A} = \mu_\ce{A}^\circ + R T \ln \frac{...
Karsten's user avatar
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-2 votes
2 answers
117 views

How is the notion that gases expand to the containing volume fit with the concept of molar volume? [duplicate]

I have a question about the concept of molar volume of a gas, which is defined as the volume occupied per mole of molecules of the gas. I don't know details about what a gas is at a deep level, but ...
xoux's user avatar
  • 144
0 votes
4 answers
303 views

How to obtain the value of the gas constant R = 8.20574 × 10⁻² L atm K⁻¹ mol⁻¹

While reading a chemistry book, I saw a table of values of the gas constant for different units. For example, $$R=8.20574\times 10^{-2}\ \text{L}\cdot\text{atm}\cdot \text{K}^{-1}\cdot \text{mol}^{-1}\...
xoux's user avatar
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-4 votes
1 answer
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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 ...
Aakash's user avatar
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1 vote
1 answer
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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 ...
Alexander Patrus's user avatar
0 votes
0 answers
62 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). ...
expiredbiscuit's user avatar
-1 votes
1 answer
58 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. ...
Jane902's user avatar
  • 111
0 votes
2 answers
441 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 ...
Mailbox's user avatar
  • 259
0 votes
1 answer
67 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 ...
Jane902's user avatar
  • 111
0 votes
2 answers
297 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 ...
Jane902's user avatar
  • 111
3 votes
2 answers
364 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 ...
Lambda's user avatar
  • 41
5 votes
2 answers
224 views

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 ...
scmartin's user avatar
-2 votes
2 answers
129 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 ...
Bhavishya Singhal's user avatar
-4 votes
1 answer
104 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'...
Paras Gupta's user avatar
1 vote
1 answer
99 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 ...
Chad Porter's user avatar
-1 votes
1 answer
258 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 ...
Paras Gupta's user avatar
-2 votes
2 answers
681 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 ...
Subhadip Kar's user avatar
1 vote
1 answer
138 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 ...
Yona Romes's user avatar
2 votes
1 answer
277 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 ...
torque560's user avatar
8 votes
1 answer
718 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
0 votes
1 answer
382 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 ...
Tensor's user avatar
  • 264
1 vote
0 answers
66 views

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 ...
C. Taylor's user avatar
0 votes
0 answers
37 views

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 ...
gachaSalt's user avatar
1 vote
1 answer
283 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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-1 votes
1 answer
289 views

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 ...
namish's user avatar
  • 37
4 votes
0 answers
71 views

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
0 votes
0 answers
251 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 ...
scmartin's user avatar
1 vote
0 answers
215 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 ...
Srihari's user avatar
  • 11
3 votes
0 answers
779 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
1 answer
120 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 ...
Chern-Simons's user avatar
2 votes
1 answer
509 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:$$R\propto1/\sqrt T$$ ...
stonecraft bros's user avatar
-1 votes
1 answer
1k views

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 $\...
jhjhjh's user avatar
  • 1
2 votes
1 answer
301 views

Converse of ΔU = 0 for isothermal processes: is it true?

For an ideal gas undergoing an isothermal process $\Delta U = 0.$ But is the converse true? Let's say, $\Delta U$ for an ideal gas is zero. Is its temperature constant then? Can we say that it's ...
Sephin's user avatar
  • 39
1 vote
0 answers
76 views

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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