## Pressure Equation

Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

Marsenne Cabral 1A
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Joined: Fri Sep 28, 2018 12:19 am

### Pressure Equation

When would you use the -nRTln(P1/P2) equation?

Henry_Phan_4L
Posts: 68
Joined: Fri Sep 28, 2018 12:24 am

### Re: Pressure Equation

Use it when they give you a change in pressure that isn't from a volume change. For example they would say that a cylinder is filled with an ideal gas which increases its pressure from 1 to 10 atm.

Michael Torres 4I
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### Re: Pressure Equation

This equation would be most applicable when calculating the change in entropy from a pressure change.

Yvonne Du
Posts: 64
Joined: Fri Sep 28, 2018 12:23 am

### Re: Pressure Equation

When the temperature is constant, you can either use V2/V1 or P1/P2 depends on what you are given because in the formula PV=nRT, P and V has a proportional relationship.

Niveda_B_3I
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### Re: Pressure Equation

When you are calculating an entropy change due to pressure, and not volume.

Kirsty Star 2H
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Joined: Fri Sep 28, 2018 12:24 am

### Re: Pressure Equation

This equation is exactly the same if it were (v2/v1) since from the ideal gas law pv=nRT, you know that pressure and volume are inversely proportional. it just depends what the problem gives you

Posts: 38
Joined: Fri Sep 28, 2018 12:22 am

### Re: Pressure Equation

When calculating change in entropy given constant Temperature, moles, and volume

Jacqueline Duong 1H
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Joined: Fri Sep 28, 2018 12:28 am

### Re: Pressure Equation

You would use that equation when there is a change in pressure.