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Sublimiation

Posted: Wed Jan 11, 2017 10:04 pm
by Justin_Ching_3I
I read in the course reader that sublimation is solid changing into vapor. Is vapor changing solid sublimation as well? If not, what is it called?

Re: Sublimiation

Posted: Wed Jan 11, 2017 10:07 pm
by Manvita_Mareboina_3K
If a vapor changes into a solid, this is known as deposition which is the opposite of sublimation.

Re: Sublimiation

Posted: Thu Jan 12, 2017 12:29 am
by NinaSheridan
I looked this up too and also found that in the case of liquids going to solids (the opposite of fusion) it's technically called solidification or crystallization if that ever comes up anywhere :)

Re: Sublimiation

Posted: Thu Jan 12, 2017 3:46 pm
by Jeffreyho97
I may be wrong, but when I asked my TA this question, she said that in this course, the reverse of such phase change as sublimation would still be called the same. The difference is that the Delta H has a reversed sign: + to - .

Re: Sublimiation

Posted: Thu Jan 12, 2017 3:56 pm
by Chris_Rudewicz_3H
No, that would be like saying when water turns into ice it's called melting. I believe it is called deposition.

Re: Sublimiation

Posted: Fri Jan 13, 2017 10:03 am
by Aashi_Patel_3B
Adding onto the topic of sublimation, when we calculate the phase change reaction of sublimation, do we only calculate vapor and solid changes? Or do we follow the line of phase change, including the liquid part?

I remember the TA saying we always have to calculate ALL steps in between (that we cant skip phase changes), was hoping for clarification.

-Aashi

Re: Sublimiation

Posted: Fri Jan 13, 2017 4:48 pm
by Chiao-Wei Cheng 3e
I could be incorrect, but I remember that we have to calculate all of the phase changes for sublimation.
(link: http://chem.libretexts.org/Core/Physica ... ublimation)

The heat of sublimation can be calculated by H(gas)-H(solid) or by adding the heat of fusion and heat of vaporization together.