## Constant P vs Constant V [ENDORSED]

MorganYun1H
Posts: 59
Joined: Thu Jul 13, 2017 3:00 am

### Constant P vs Constant V

I know that when P is constant, q=deltaH for the reaction. What happens when V is constant? Is there a certain relationship between these two?

Humza_Khan_2J
Posts: 56
Joined: Thu Jul 13, 2017 3:00 am

### Re: Constant P vs Constant V

From what I understand, q=cdeltaT regardless of constant V or P; however, the C constants would differ in these two distinguishable scenarios.

Chem_Mod
Posts: 18211
Joined: Thu Aug 04, 2011 1:53 pm
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### Re: Constant P vs Constant V  [ENDORSED]

I discussed this earlier today online. See previous posts.
Summary:

$\Delta U=q+w$

When volume is constant then $\Delta V=0$ and w = 0.

Therefore $\Delta U$ = qv

I will discuss all of this in detail in class next week when we start thermodynamics.

This week we are covering the 2nd half of Chapter 8 which is thermochemistry.

Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

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