## Heating Capacity

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

Tiffany Cao 1D
Posts: 94
Joined: Fri Sep 29, 2017 7:03 am
Been upvoted: 1 time

### Heating Capacity

In which cases would we use 3/2*R=Cv and 5/2*R=Cp? I noticed in 9.43, the solution used the actual heating capacity of water(75.29J/Kmol), but when would we ever use the other heating capacity rules?

Curtis Wong 2D
Posts: 62
Joined: Sat Jul 22, 2017 3:00 am

### Re: Heating Capacity

In Problem 9.43, we use the molar heat capacity of water in a liquid form because we have that information to do so. We know the heating capacity of water, and we needed to find the temperature in K (which is why we used Molar heat capacity).

In regards to your other questions, the R is the ideal gas constant, so we would only use the Heat Capacity of an Ideal Gas at Constant Value (Cv) or the Heat Capacity of an Ideal Gas at a Constant Pressure (Cp) when we are working with ideal gases (also depends on whether or not they're diatomic as well).

Ivy Lu 1C
Posts: 54
Joined: Thu Jul 27, 2017 3:00 am

### Re: Heating Capacity

The heat capacities, 3/2*R=Cv and 5/2*R=Cp, relate to when there is an ideal gas at constant volume/pressure. For this problem, the water is in its liquid state, so the heat capacity of an ideal gas would not apply.

veneziaramirez 3I
Posts: 57
Joined: Fri Sep 29, 2017 7:07 am

### Re: Heating Capacity

Does it matter which equation we use to find heat capacity? Will the formula for specific heat capacity and molar heat capacity give the same thing?