## Differences in Heat Capacity

Gabriel Ordonez 2K
Posts: 113
Joined: Sat Jul 20, 2019 12:15 am

### Differences in Heat Capacity

What are the different types of heat capacities we should take into account for this class?

Ally Huang- 1F
Posts: 103
Joined: Thu Jul 25, 2019 12:16 am

### Re: Differences in Heat Capacity

Heat capacity is the heat required to raise the temperature of an object by 1 degrees celsius. Specific heat capacity is the heat required to raise temperature of 1 gram of a substance by 1 degrees celsius. Molar heat capacity is the heat required to raise the temperature of one mole of a substance by 1 degrees celsius. Gasses have a molar heat capacity specific for a gas at a constant volume and a constant pressure.

Mulin_Li_2J
Posts: 105
Joined: Sat Aug 17, 2019 12:16 am

### Re: Differences in Heat Capacity

Another two heat capacity you might want to understand is Cv,m, molar heat capacity of gas under constant volume, and Cp,m, molar heat capacity of gas under constant pressure. Using C = q/T and q(constant pressure) = ΔH and ΔH = ΔU + PV, we can derive the equation that Cp,m = Cv,m + R. Then based on equipartition theorem, we can deduce that Cv,m = (3/2)*R for monoatomic gas, thus Cp,m = (5/2)*R. There is a table somewhere in the textbook with Cv,m and Cp,m for momatomic, linear, and non-linear gas respectively.

Hope this can help!!! -_+

JasonLiu_2J
Posts: 109
Joined: Sat Aug 24, 2019 12:17 am

### Re: Differences in Heat Capacity

It might also be good to know that the heat capacity for a substance is an extensive property, as it depends on how much of the substance is present. Specific heat capacity (energy required to heat a gram by 1 degrees C) and molar heat capacity (energy required to heat a mol by 1 degrees C), are intensive properties which are constant values for specific substances. Monatomic ideal gases have a special molar heat capacity that you can calculate by using 3/2R under constant volume and 5/2R under constant pressure. This of course indicates that all monatomic ideal gases have the same molar heat capacity under constant volume or constant pressure. Hope this helps!

Aiden Metzner 2C
Posts: 104
Joined: Wed Sep 18, 2019 12:21 am

### Re: Differences in Heat Capacity

We need to know heat capacity for calorimeters, which is just the heat capacity required to raise a substance 1 degree celcius. But also specific and molar heat capacities are important to know. Specific being the amount of heat required to raise 1 gram of a substance 1 degree celcius, and molar being the amount of heat required to raise a mole of a substance 1 degree celcius