All Questions
18 questions
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Why thermodynamic equilibrium and pressure balance is considered for having a reversible process? [duplicate]
When we compare the rapid expansion of an ideal gas to a very slow expansion from an initial state to a final state, we categorize one as irreversible and the other as reversible. This distinction ...
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24
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Pressure difference between a box and the outside atmosphere
Say I have a box of volume $V$, with an ideal gas inside it with temperature $T_b$. I don't know the number of particles inside it. The box is surrounded by the room's environment, which has ...
- 143
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2
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77
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What regulates the size of our atmosphere?
Our atmosphere is only about 100km thick before the official start of space. That is a mere 1.57307% of the radius of Earth (6,357km). The difference between the gratitational force at sea level and ...
- 413
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3
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125
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Is the pressure zero in thermal equilibrium? [duplicate]
In a canonical ensemble, we have $dU=TdS-pdV$. When we are in equilibrium, the energy $U$ is minimized. This implies that $\left(\frac{dU}{dV}\right)_S=0$. Since $\left(\frac{dU}{dV}\right)_S=-p$, we ...
- 1,492
2
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1
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148
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Osmotic pressure "equilibrium"?
Consider a box with two compartments separated by a semipermeable membrane. The first compartment is initially at pressure $P_0$ and contains the solvent ; the second compartment is initially at ...
- 135
3
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1
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276
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Temperature and pressure being equal at equilibrium (from first law of thermodynamics)
I have a question in which an insulated container of gas with volume $V$ is divided into two parts $V_1$ and $V_2$ by a movable barrier through which energy can pass, and need to show that, using the ...
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1
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341
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Is the pressure always the same for each phase of a two-phase system?
I am currently reading a textbook called Engineering and Chemical Thermodynamics but I am stuck in one part about the State Postulate and the Gibbs Phase Rule. The Gibbs Phase rule says that the ...
- 97
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2
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122
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Hydrogen in soap bubble
I read somewhere that if hydrogen gas is passed through soap solution bubbles containing hydrogen are formed. My question is how these bubbles are stable! Hydrogen has much less density and mass than ...
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83
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A gas immersed in a higher-pressure gas: spherical shape?
I'm considering a bubble of gas of some arbitrary shape immersed in another gas of higher pressure. There is no gravity (and hence no buoyancy), the gases are ideal (so there are no attractive forces ...
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15
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8
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6k
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Why (does/we assume) gas exert same pressure everywhere in a closed container?
I was reading about the gaseous state when this question struck my mind: What made us assume that, at every point inside the container, a gas exerts equal pressure? When one brings a barometer, is it ...
- 522
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2
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315
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Thermodynamic equilibrium state of constant $(p,S)$ system
The internal energy as a function of its natural variables is:
$$dU=-p dV+TdS$$
where $p$ is the system pressure and $dS$ includes only changes of the entropy due to heat transfer (the "...
- 474
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2
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629
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Pressure of a system at the thermodynamic equilibrium
I'm reading a book in which it says that a system is at mechanical equilibrium if the pressure is constant in time but not necessarily uniform in space at any fixed point (for example it can be caused ...
- 768
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2
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504
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Moles of gas in a VLE mixture
I have a system in vapor-liquid equilibrium which also has some gas inside (let's say that the VLE system is Water and the gas is Air). The system looks like this:
There is some heat applied to it ...
- 564
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2
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349
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Pressure Difference affecting reversibility of a process
It is said that for a finite pressuredifference between system and the surrounding the process is irreversible. From the diagram can you please tell me how the process is irreversible ?
Does this ...
- 151
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2
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883
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Reversible processes in which mechanical or thermal equilibrium is not reached
The definition of a reversible thermodynamic process requires in any instant the mechanical equilibrium (equal pressures) and thermal equilibrium (equal temperatures) of the system in a quasi-static ...
- 2,637
1
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1
answer
217
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Gas/liquid pressure equilibrium of water in an exotic environments
So I'll preface this by saying this is not some evil homework assignment, this came about from some idle talk of colonizing the moon by a couple of software engineers when we realized we had no idea ...
- 193
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Mechanical equilibrium: thermodynamics and classical mechanics
A similar question was asked here but mine is a bit different.
In thermodynamics, a mechanical equilibrium is defined as a uniform pressure (for a fluid).
In classical mechanics, equilibrium is ...
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Calculating the amount of dissolved gases in a liquid?
The most basic situation, water at room temperature, has dissolved oxygen, CO2, and more. Why is this? How would one calculate how much gas should be dissolved in any given liquid?
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