CHEMISTRY COMMUNITY

What determines a substance's molar heat capacity? From Cv,m = delta U/delta T, it appears that molar heat capacity would depend on the change in internal energy and temperature of a monatomic gas, but molar heat capacities are independent of temperature, so I'm unsure of what actually determines them. Thanks so much!

Molar heat capacity is the amount of heat needed to raise one mole of a substance by one degree Kelvin, and is dependent on the intermolecular forces between the particles. For example, a substance with strong intermolecular forces (such as water, which has hydrogen bonds) would have a higher heat capacity than a substance with weaker intermolecular forces.

Heat capacity is dependent on temperature, as you mentioned with C_v = ΔU/ΔT (equation for heat capacity at a constant volume).

To find the molar heat capacity at a constant volume, you take C_v and divide it by however many moles of substance you have. You're looking for the heat capacity per unit (mole) of pure substance. C_v,m = C_v /m