CHEMISTRY COMMUNITY

How do constant pressure and temperature affect calculations for internal energy?

Constant temperature (isothermal) indicates that delta U is 0. Constant pressure allows you to set q equal to delta H, and the work is -PdeltaV.

sbeall_1C wrote:Constant temperature (isothermal) indicates that delta U is 0. Constant pressure allows you to set q equal to delta H, and the work is -PdeltaV.

And internal energy=0 when the process is isothermal because internal energy is heat transfer. So if the temperature is not changing then there will be no change in internal energy and this is where we derive the equation q=-w