## Calculating Heat [ENDORSED]

$\Delta U=q+w$

Taylor_Lam_1E
Posts: 9
Joined: Wed Sep 21, 2016 2:58 pm

### Calculating Heat

For question 8.41 in the text book, q1 = mCΔT, but for q2 it was mCΔT + nΔHf. Just wondering what the "nΔHf" added to it is for, and why it was needed for this problem as opposed to others.

Theresa Dinh 3F
Posts: 26
Joined: Fri Jul 22, 2016 3:00 am

### Re: Calculating Heat  [ENDORSED]

It sounds like it's referring to calculating the energy it takes to convert between states of matter.

Mihika Sridhar 3H
Posts: 11
Joined: Wed Sep 21, 2016 2:58 pm

### Re: Calculating Heat

Yes, it's definitely referring to the heat needed switch to another state of matter (I.e. Gas to liquid or liquid to solid, calculated with nHf) in addition to the heat needed to get the final state of matter to the desired temperature (that part is just mc(tf-ti)).

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