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Phase Changes

Posted: Sat Jan 13, 2018 12:29 pm
by itzeelpadillaDis1A
What are the exothermic phase changes?

Re: Phase Changes

Posted: Sat Jan 13, 2018 12:52 pm
by Sue Xu 2K
Condensation, solidification and deposition are all exothermic phase change that release heat during the process.

Re: Phase Changes

Posted: Sat Jan 13, 2018 2:42 pm
by Dylan Mai 1D
Are we supposed to know the specific terms for those phase changes listed above? Like fusion for example

Re: Phase Changes

Posted: Sat Jan 13, 2018 3:31 pm
by Arjun Sharma 1D
It would probably be a good idea to know the names of the different phase changes in case they just use the specific name w/o description in a problem @Dylan Mai 1D

Re: Phase Changes

Posted: Sat Jan 13, 2018 4:02 pm
by Shanmitha Arun 1L
It would be best to know the enthalpy of fusion and the enthalpy of vaporization as it is used in calculations.

Re: Phase Changes

Posted: Sat Jan 13, 2018 5:49 pm
by Christina Bedrosian 1B
An easy way to think about this is that exothermic releases heat, meaning usually involving cooling, so the phase changes being exothermic would be from gas to liquid (condensation), liquid to solid (freezing), or gas to solid.

Re: Phase Changes

Posted: Sat Jan 13, 2018 7:49 pm
by Ishita Monga 1B
Sue Xu 2K wrote:Condensation, solidification and deposition are all exothermic phase change that release heat during the process.

follow up- what is deposition?

Re: Phase Changes

Posted: Sat Jan 13, 2018 7:54 pm
by Chem_Mod
An exothermic reaction is a process by which energy is outputted from the system leaving the products with less overall energy than the reactants. This includes certain phase changes (like melting and condensation) for physical changes of substances, but may also include a reaction with a negative enthalpy of reaction.

Re: Phase Changes

Posted: Sat Jan 13, 2018 8:11 pm
by Naomi Jennings 2H
Ishita Monga 1B wrote:
Sue Xu 2K wrote:Condensation, solidification and deposition are all exothermic phase change that release heat during the process.

follow up- what is deposition?

Deposition is the process of a vapor going straight from vapor to solid. It's the reverse of sublimation.

Re: Phase Changes

Posted: Sat Jan 13, 2018 8:57 pm
by RohanGupta1G
Exothermic phase changes are ones that release heat such as a gas turning into a liquid or solid, or a liquid turning into a solid. As the temperature lowers, energy is released and the phase changes.

Re: Phase Changes

Posted: Sat Jan 13, 2018 10:35 pm
by Michelle Lee 2E
Think of exothermic as something that is cooler as a result of a reaction so gas to liquid (condensation: an example is water droplets on a window from fog) and liquid to solid (freezing: ice).
Endothermic, then, would be something retaining heat like ice retaining heat and melting.

Re: Phase Changes

Posted: Sat Jan 13, 2018 10:48 pm
by Natalie LeRaybaud 1G
The exothermic phase changes are the ones that occur going down a heat curve. This is because they are releasing energy during the reaction and therefore have energy as a product and have a negative delta H (enthalpy). This includes freezing, condensation, and deposition as stated above.

Re: Phase Changes

Posted: Sat Jan 13, 2018 11:54 pm
by Gwen Peng 1L
Fusion, vaporization, and sublimation are endothermic processes, whereas freezing, condensation, and deposition are exothermic processes.

Re: Phase Changes

Posted: Sun Jan 14, 2018 1:30 am
by Michelle Lu 1F
Exothermic reactions release heat, and therefore the product will be colder. This means that the exothermic phase changes are going down the heat curve, including freezing, condensation, and deposition.