Questions tagged [ideal-gas]

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How much energy is required to liquify oxygen?

Does anyone know where I can find some documentation of a real-world liquification process, and the energy costs? I can calculate the heat that must be removed from O2 gas to get to liquid, but how ...
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1answer
50 views

How can change in Enthalpy for a reaction be written like this?

If a gas expands in a container with constant external pressure then: $W=-P_{ext}\Delta V$ Instead of $P_{ext}$ if we use $P_{int}$ then we will not get the same value because $P_{int}$ is constantly ...
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38 views

How much energy is required to operate a Sabatier Reactor?

I'm trying to model some industrial processes and having a hard time finding information about the Sabatier reaction. The sabatier reaction combines CO2 (and possibly CO) with H2 to produce H2O and ...
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1answer
67 views

Find gas pressures of injection knowing mixture pressure without knowing volume

Let's say we have a gas 1 moving inside a pipe (we don't know the geometry) at mass flow rate $Q_1$ and temperature $T_1.$ We inject a gas 2 at some point inside the pipe with gas 1 at mass flow rate $...
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3answers
70 views

Specific Heats for Non-Constant Processes

Why can the specific heat at constant Pressure ($C_p$) be used to calculate the change in enthalpy as $\text{d}H = C_p\text{d}T\newcommand{\d}{\text{d}}$ for processes that are not even at constant ...
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1answer
81 views

Volume of ideal gas molecule [closed]

Is there any reason as to why we assume the volume of ideal gas to be negligible in comparison to the container? What is the underlying reason to assume that the ideal gas molecules are point ...
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1answer
42 views

How does an irreversible process maintain internal energy while dissipating excess heat? [closed]

From my understanding, if you were to look at a pressure-volume graph of a reversible, isothermal expansion, the area under it would represent reversible work. Similarly, if you were to graph an ...
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1answer
124 views

How does one prove Avogadro's law from Gay-Lussac's?

To understand Gay-Lussac's law, Amedeo Avogadro said In equal volumes of air under constant temperature and pressure, there are equal number of atoms (or molecules). Let's take a hydrogen and an ...
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1answer
42 views

Particules speed in ideal gasses [closed]

According to Graham's law, we can calculate de average speed of gasses by using the formula $$v^2=\frac{3RT}{M}$$ I tried to use this simulation and got these data by keeping same particles amount and ...
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1answer
42 views

Work done by system of ideal gas in isobaric expansion

Consider a system of ideal gas in a container with piston and the isobaric expansion of gas takes place. As the process is isobaric, so initially the pressure of gas is equal to atmospheric pressure ...
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1answer
33 views

Consider difference of pressures as weight of piston [closed]

Let us say there is a container with two ideal gases in it divided by a piston.Volume of ideal below the piston is 2L and above is 8L.Total volume of container is 10L. n of both is 1 mole and T is 300 ...
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68 views

Volume of compressed helium gas needed for FE test on ball valves

I'm currently doing a case study to find out the exact volume of helium gas required for FE tests on ball valves regards to the valves' volume and pressure class and the number of helium tanks needed ...
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1answer
439 views

Will entropy increase in adiabatic expansion? [closed]

The formula for entropy change states that change in entropy is not possible if heat change is nil. ∆S=∆Q/T But what if we adiabatically expand a gas? Won't the molecules get more space to vibrate in, ...
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44 views

Why is the concentration term in van der Waals correction for ideal gas squared? [duplicate]

In van der Waals correction for ideal gas equation, the pressure term has a correction where concentration term is squared. I saw derivations for this and they say that the concentration is squared ...
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1answer
42 views

interconverting Van Der Waal's equation for real gases from number of molecules to density

I want to ask a question about Van Der Waal's equation for real gases. I was shown the following formula for real gases (VDW) which accounts for the liquification of water vapour which is not possible ...
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2answers
527 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 ...
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64 views

Why is vapor pressure constant at boiling point?

At non-boiling point, I understand that when you add heat, temperature increases and also the amount of gas increases, so by using $PV=nRT$ at constant volume, the increase in $n$ and $T$ would ...
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1answer
81 views

Specific Heat Ratio for a perfect gas mixture

I am reading Rocket Propulsion Elements by George P. Sutton & Oscar Biblarz, 9th Edition. In the fifth chapter, I was introduce to the specific heat ratio k for the perfect gas mixture, Eq. 5-7. ...
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1answer
50 views

describing in words a primitive heated water vapor lift

The primitive lift illustrated in the left hand side of the following figure operates using heated water vapor ("gas") that pushes on a sealed piston. During its operation, the vapor ...
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0answers
65 views

Interpreting a thermodynamics equation using a picture

Given $$ \frac{\partial \Gamma}{\partial p}\Bigg|_{t} =\frac{\partial \Gamma}{\partial p}\Bigg|_{v}+\frac{\partial v}{\partial p}\Bigg|_{t}\frac{\partial \Gamma}{\partial v}\Bigg|_{p} \tag{1}$$ where \...
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2answers
111 views

Chemical potential and gibbs free energy

I would like to ask why the $\Delta_rG_1 = -RT\ln K + RT\ln Q$ is not equal to $Δ_rG_2$ numerically as shown in the figure where I derived $\Delta_rG_2 = RT\ln Q$ using a cyclic ring since $\Delta_rG$ ...
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23 views

How do we define “volume” of the gas undergoing free expansion in vacuum? [closed]

Usually volume occupied by the gas is defined as the the volume of the container, but as it expands freely (Joule's free expansion), we can't say anything about volume in a concrete sense as we don't ...
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1answer
70 views

Are chemical treated as ideal gases when trying to figure out heat of formation using calorimetry?

At 36:48 of this video lecture, The professor says that the reaction moving from reactants to products keeping temperature of both same and under standard condition is an isothermal constant volume ...
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29 views

Why do internal energy/heat and enthalphy differ? What is the physical significance of the $PV$ term for enthalphy of an ideal gas? [duplicate]

Let it be noted that this is not a duplicate of this downvoted-to-hell question, simply because I hope to ask it better! I've been reading a thermo textbook and I've got a simple question. The ...
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1answer
433 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.
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39 views

Finding percent contamination of sulfur dioxide in air by redox reaction with iodine

I would really like some help with this problem. My work is at the bottom. I've tried multiple ways and have gotten the same answer for both, but for some reason the computer program won't accept the ...
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15 views

The interactions of the high energy gas particles

When we are talking about the idealization of the gas, why for high temperatures its particles interact less? I would say you have a bigger probability of the collisions among particles. Quantum ...
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1answer
53 views

Relationship between the partial pressure $p_J = x_J p$ and the perfect gas law $pV = nRT$

I am currently studying Atkins' Physical Chemistry, 11th edition, by Peter Atkins, Julio de Paula, and James Keeler. Chapter 1A.2 Equations of state says the following: When dealing with gaseous ...
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2answers
43 views

Calculating the molar volume of a perfect gas under standard ambient temperature and pressure [duplicate]

I am trying to calculate the molar volume of a perfect gas under standard ambient temperature and pressure, but I'm having problems with the units. $$\begin{align} V_m = \dfrac{RT}{p} &= \dfrac{(8....
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68 views

Calculating force and pressure of an ideal gas on a wall [duplicate]

The text below is from a discussion on ideal gases and the kinetic theory of gases: After the collision the molecule must travel a distance $l$ to the opposite wall, and then back across this same ...
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2answers
457 views

Pressure exerted by a particle of ideal gas

There is a step I fail to grasp in the proof that for a monatomic ideal gas, $U=\frac{3}{2}PV$, where $U$ denotes the internal energy of the gas. The proof involves considering a particle with mass $m$...
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1answer
79 views

A Curious (definitely wrong) result of Absolute Entropy [closed]

The Gibbs free energy is defined as $$G=H-TS$$ Differentiating both sides $$dG=dH-TdS-SdT$$ For an adiabatic reversible expansion of an ideal gas, we would have $dG=0$, and $dS=0$. Thus we can write, $...
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2answers
77 views

Can Gay-Lussac's law be observed in the reverse direction?

Gay-Lussac's law states that if you decrease the temperature of a gas at constant volume, the pressure decreases by a corresponding amount. This is easy to carry out experimentally. But in practice is ...
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65 views

How to convert pCO2 (uatm) in seawater to grams

I have seawater pCO2 measurements, and I need to convert them from uatm to moles or grams for around a 50m depth integration. I know the solubility coefficient and temperature among other data. For ...
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1answer
69 views

Does the property of additivity for the amounts of different substances hold up for ideal gas law?

A mixture contains $\pu{8.00 g}$ each of $\ce{O2},$ $\ce{CO2},$ and $\ce{SO2}$ at STP. Calculate the volume of this mixture. Which of the gases would exert the greatest pressure and why? Here is my ...
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1answer
62 views

Thermodynamic model of inclusion process of alpha-cyclodextrin

I have a question about thermodynamic model of inclusion process of CD, published by Tabushi (DOI: 10.1021/ja00471a043). Here, in 3rd step, action is described as: "An apolar solute (guest molecule) ...
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1answer
347 views

The connection of the “R” in the ideal gas law and osmotic pressure [closed]

I am studying chemistry and biology at the same time, and have encountered a problem. In the ideal gas law, the $R$ is the ideal gas constant, and its value is $\pu{0.0821 L atm mol-1 K-1}.$ However, ...