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2 molar heat capacities of ideal gas

Posted: Mon Feb 11, 2019 10:24 pm
by Karina Koo 2H
Can someone explain to me why the heat capacities for gas at a constant pressure are higher than that at constant volume? Thank you!

Re: 2 molar heat capacities of ideal gas

Posted: Mon Feb 11, 2019 10:43 pm
by Matthew Tran 1H
In simple terms, at constant volume, adding heat to the gas would only raise its temperature, but at constant pressure, some of the energy supplied as heat also goes towards expansion work. Thus, it would take a greater amount of heat to raise the temperature of an ideal gas by 1 degree Celsius under conditions of constant temperature vs. constant volume. The more rigorous derivation is located in section 4C.2 in the 7th edition.