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### heat capacity at constant V and constant P

Posted: **Wed Feb 05, 2020 10:38 pm**

by **Michael Du 1E**

Can anyone please explain why q = delta U in the equation for the heat capacity at constant volume and why q = delta H in the equation for the heat capacity at constant pressure? Thank you

### Re: heat capacity at constant V and constant P

Posted: **Wed Feb 05, 2020 11:26 pm**

by **chemboi**

at constant volume, q = delta U because no work is being done in expansion, so w is zero. q+w = delta U, so only q is left over. If someone could clarify the second part, that would be great because I'm not sure :(

### Re: heat capacity at constant V and constant P

Posted: **Thu Feb 06, 2020 12:13 am**

by **Adriana_4F**

The definition of Enthalpy (deltaH) is the amount of heat released or absorbed at a constant pressure, so qp and deltaH can be used interchangeably.