phase changes  [ENDORSED]

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Amanda Salgado 3D
Posts: 22
Joined: Wed Sep 21, 2016 3:00 pm

phase changes

Postby Amanda Salgado 3D » Sat Jan 14, 2017 12:54 pm

Just to clarify, when going from up from a solid, to liquid, to gas...the result is a positive number, and when going down from a gas, to a liquid, to a solid, the result is a negative number?

Caitlin Dillon 3G
Posts: 26
Joined: Wed Sep 21, 2016 2:56 pm

Re: phase changes  [ENDORSED]

Postby Caitlin Dillon 3G » Sat Jan 14, 2017 1:04 pm

Correct. In order for a solid to go to a liquid, it must absorb heat, so it is endothermic and positive delta H. When a liquid goes to a solid, it must release heat, so it is exothermic and negative delta H.

Posts: 15
Joined: Wed Sep 21, 2016 2:55 pm

Re: phase changes

Postby yoonjong_han_3F » Sun Jan 15, 2017 5:59 pm

So, as Dr. Lavelle mentioned in lecture,

when you touch the object at 100 celsius, there will be transfer of heat to your hand! So, it is exothermic

Yasmine Choroomi 2C
Posts: 25
Joined: Fri Jul 22, 2016 3:00 am

Re: phase changes

Postby Yasmine Choroomi 2C » Tue Jan 17, 2017 1:13 pm

Going from a solid to a liquid is endothermic and heat is absorbed! because we look at everything in terms of the system, delta H is positive because heat must go in!

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