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### Difference between delta U and delta H?

Posted: Mon Feb 11, 2019 1:16 am
What is the difference between delta U and delta H?

Delta U is the change in internal energy of a system... and delta H is the change in heat energy. What is the difference between the two in respect to a system?

### Re: Difference between delta U and delta H?

Posted: Mon Feb 11, 2019 1:22 am
Delta H refers to the change in energy/heat at constant pressure, that is exchanged between the surroundings and system. This means that if you are adding 10 J to the system, you are taking away 10 J from the surroundings (-10 J).

### Re: Difference between delta U and delta H?

Posted: Mon Feb 11, 2019 8:59 am
I agree with above post. delta U = q + w in that it includes changes in heat (or enthalpy depending on whether its a constant pressure environment). Delta U can change for the following reasons: (1) matter is being added or removed (2) change in work (3) change in heat. Enthalpy, is exclusively the heat transferred at constant pressure. So, you can think of delta U as encompassing delta H or q.

### Re: Difference between delta U and delta H?

Posted: Tue Feb 12, 2019 9:44 am
Delta H is equal to q at constant pressure, whereas delta U=q+w.