Heat & Temperature of Phase Changes

Moderators: Chem_Mod, Chem_Admin

Angela Wu-2H
Posts: 50
Joined: Fri Aug 30, 2019 12:16 am

Heat & Temperature of Phase Changes

Postby Angela Wu-2H » Sun Feb 09, 2020 6:39 pm

Under my class notes, it states "Because heat is required during melting or boiling (phase transitional), the temperature of the sample remains constant even though heat is being supplied."

Is this basically saying temperature stays constant because the heat required cancels out with the heat being supplied? What guarantees that the exact same amount of heat required is the exact same amount of heat that is being supplied?

Wilson 2E
Posts: 100
Joined: Sat Aug 17, 2019 12:18 am

Re: Heat & Temperature of Phase Changes

Postby Wilson 2E » Sun Feb 09, 2020 6:47 pm

At a temperature where phase change occurs, heat energy is being used to separate molecules rather than change the temperature of the substance, resulting in a constant temperature.

305385703
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

Re: Heat & Temperature of Phase Changes

Postby 305385703 » Sun Feb 09, 2020 6:55 pm

There is no set rate of how much heat is being used to change phase. There is a certain amount of heat that is required to change phases, and once that amount of heat is inputted into the substance, it changes phase and any more heat added contributes to the temperature.

Isabella Dal Porto 1H
Posts: 100
Joined: Fri Aug 30, 2019 12:16 am

Re: Heat & Temperature of Phase Changes

Postby Isabella Dal Porto 1H » Sun Feb 09, 2020 6:59 pm

When there is a phase change, temperature remains constant for a period of time because all the heat added is being used to break bonds.

Callum Guo 1H
Posts: 134
Joined: Fri Aug 02, 2019 12:15 am
Been upvoted: 1 time

Re: Heat & Temperature of Phase Changes

Postby Callum Guo 1H » Sun Feb 09, 2020 7:21 pm

It takes energy to change phases. (heat of vaporization, heat of fusion)

405268063
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

Re: Heat & Temperature of Phase Changes

Postby 405268063 » Sun Feb 09, 2020 7:35 pm

If you look at the graph Dr. Lavelle drew of q versus T early on in thermochemistry, you can see that at the phase changes, the graph plateaus.


Return to “Phase Changes & Related Calculations”

Who is online

Users browsing this forum: No registered users and 2 guests