## Calculating the change in entropy of the surroundings

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Adriana_Bustamante_3L
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

### Calculating the change in entropy of the surroundings

Where does the equation $\Delta H_freeze=-\Delta H_fus$ come from? This is used in example 9.10 when calculating the change in entry of the surroundings when mercury freezes at 224K and $\Delta H_fus=2.292kJ/mol$

Evan Lee 2D
Posts: 18
Joined: Wed Sep 21, 2016 2:58 pm

### Re: Calculating the change in entropy of the surroundings

From my understanding, I think of freezing and melting as opposites. Thus, the enthalpy that is needed to freeze something is opposite of the enthalpy change necessary to melt something. The opposite is indicated by the negative value.

When an amount of heat is gained by something, the surroundings lose the same amount of heat. The magnitudes are equal, but the direction at which they are moving is not.

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