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### Enthalpy Formula

Posted: **Sun Feb 09, 2020 6:31 pm**

by **Jasmine 2C**

In lecture, we went over 3 methods to calculate enthalpy as well as ΔH = H(products) - H(reactants). In the textbook, they have the formula ΔH = ΔU + PΔV. Are we not allowed to use this formula (alongside ΔU = q + w) to calculate the change in enthalpy?

### Re: Enthalpy Formula

Posted: **Sun Feb 09, 2020 6:42 pm**

by **Jared_Yuge**

We can definitely use that equation, cause its just a reworked 1st law equation. Under constant pressure q=delta H and w= -P deltaV

### Re: Enthalpy Formula

Posted: **Sun Feb 09, 2020 6:45 pm**

by **Angela Wu-2H**

The formula is basically derived from each other, so I believe we could use both.

qp=delta H so

delta U = q+w ------> delta U = delta H + w

w = -p*delta V -------> delta U = delta H -p*delta V

solve for delta H so...

delta H = delta U + p*delta V