Enthalpy of Freezing

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Samantha Kan 2L
Posts: 30
Joined: Sat Jul 22, 2017 3:00 am

Enthalpy of Freezing

Postby Samantha Kan 2L » Wed Jan 10, 2018 3:33 pm

Is the symbol for enthalpy of freezing -∆Hfus or is there another symbol we should use?

Kaelie Blanes-Ronda 2L
Posts: 42
Joined: Fri Sep 29, 2017 7:07 am
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Re: Enthalpy of Freezing

Postby Kaelie Blanes-Ronda 2L » Wed Jan 10, 2018 3:36 pm

I think its the same symbol for both freezing and melting which is ∆Hfus. It's just freezing is from liquid to solid so the value is negative because the reaction is exothermic (-∆Hfus) where as melting is endothermic (+∆Hfus).

Rana YT 2L
Posts: 49
Joined: Thu Jul 27, 2017 3:01 am

Re: Enthalpy of Freezing

Postby Rana YT 2L » Wed Jan 10, 2018 9:21 pm

That is correct but the negative is arbitrary since it depends on the direction of the phase change

Anne 2L
Posts: 35
Joined: Fri Sep 29, 2017 7:05 am

Re: Enthalpy of Freezing

Postby Anne 2L » Wed Jan 10, 2018 11:49 pm

Sorry if I'm totally off, but wouldn't the negative sign be required and not arbitrary in this case. I believe freezing is the reverse reaction of melting/fusion. Since melting/fusion is endothermic and therefore has a positive enthalpy value, wouldn't freezing be exothermic and therefore have a negative enthalpy value?

Kyle Sheu 1C
Posts: 87
Joined: Fri Jun 23, 2017 11:39 am

Re: Enthalpy of Freezing

Postby Kyle Sheu 1C » Thu Jan 11, 2018 2:20 am

Yep, that's right! I think Kaelie made a small error in her 1st statement, but everything else is correct.


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