Phase Changes Equations

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Cristina Sarmiento 1E
Posts: 52
Joined: Wed Nov 16, 2016 3:02 am

Phase Changes Equations

Postby Cristina Sarmiento 1E » Tue Jan 23, 2018 10:28 pm

Delta H fusion = Hm (liquid) - Hm (solid) as mentioned in the book and in lecture. What does Hm stand for? Are we going to have to know how to solve for delta H fusion or for the other delta H phase changes?

kaushalrao2H
Posts: 63
Joined: Thu Jul 13, 2017 3:00 am
Been upvoted: 2 times

Re: Phase Changes Equations

Postby kaushalrao2H » Tue Jan 23, 2018 11:42 pm

Hm refers to the molar enthalpy of the solid or liquid. and yes, i think we need to know to use these delta H for phase change problems.

Salman Azfar 1K
Posts: 50
Joined: Thu Jul 13, 2017 3:00 am

Re: Phase Changes Equations

Postby Salman Azfar 1K » Wed Jan 24, 2018 10:33 am

We may need to know how to solve for them in some cases but lots of questions about phase changes usually give them to us to calculate the overall heat change. Check out the textbook problems, they should show whether or not you need them.

Lily Sperling 1E
Posts: 49
Joined: Tue Oct 10, 2017 7:14 am

Re: Phase Changes Equations

Postby Lily Sperling 1E » Wed Jan 24, 2018 10:47 am

Typically deltaH(fusion) and deltaH(vap) will be given to us since what we are usually solving for is initial/final temp or the enthalpy of the reaction. I believe it is more important that you know how to distinguish and apply all of the different values given to you than it is to calculate these specific values. However, it is still important for us to know how to calculate the values in case we were ever asked to.

Michael Lee 2I
Posts: 51
Joined: Fri Sep 29, 2017 7:05 am

Re: Phase Changes Equations

Postby Michael Lee 2I » Thu Jan 25, 2018 5:16 pm

Most questions give the overall heat change but you should know how to solve for it. Doing a lot of problems in the textbook will give you a clearer idea on whether you need to know how to solve for the overall heat change.


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