The Student Room Group

Phase transition and Phase change

Most places seem to say they're the same thing but my course specifically defines them differently but I don't understand it at all - maybe phase change is a type of phase transition?

this is all I've got to go on:

"Pure materials typically show well-defined phase transitions at fixed
temperatures which depend on pressure.
For e.g. at 1 atmosphere pressure, water melts at 0 °C (273.15 K) and boils at
100 °C (373.15 K)
melting (fusion) from solid to liquid <---> freezing from liquid to solid
boiling from liquid to gas <-----> condensing from gas to liquid

Phase changes, on the other hand, take place below the transition
temperature
For example, water evaporates to vapour form at room temperature."


I have literally no idea what this means :frown: thanks for any help

edit: do phase transitions depend on temp. and phase changes on pressure?
(edited 10 years ago)
Original post by Tikara
Most places seem to say they're the same thing but my course specifically defines them differently but I don't understand it at all - maybe phase change is a type of phase transition?

this is all I've got to go on:
"Pure materials typically show well-defined phase transitions at fixed
temperatures which depend on pressure.
For e.g. at 1 atmosphere pressure, water melts at 0 °C (273.15 K) and boils at
100 °C (373.15 K)
melting (fusion) from solid to liquid <---> freezing from liquid to solid
boiling from liquid to gas <-----> condensing from gas to liquid

Phase changes, on the other hand, take place below the transition
temperature
For example, water evaporates to vapour form at room temperature."

I have literally no idea what this means :frown: thanks for any help

edit: do phase transitions depend on temp. and phase changes on pressure?


What?! :redface: I thought they were the same thing, they are on my board, AQA. What board are you on?

Posted from TSR Mobile
Reply 2
Original post by Helmet Diver
What?! :redface: I thought they were the same thing, they are on my board, AQA. What board are you on?

Posted from TSR Mobile


yeah I think for a level they are the same thing (and the rest of the world seem to think so too) i'm at uni I just posted this into chemistry at the top so sorry if its in the wrong section!
Reply 3
Water BOILS at 100 deg C, but EVAPORATES at any temperature. They want you to call the latter process a phase change, the former a phase transition.

Difference is obvious, I am not sure this naming is universally accepted - but then English is my second language.
Reply 4
Original post by Borek
Water BOILS at 100 deg C, but EVAPORATES at any temperature. They want you to call the latter process a phase change, the former a phase transition.

Difference is obvious, I am not sure this naming is universally accepted - but then English is my second language.


cheers mate yeah I asked some people and thats right - came up on the exam and all :P

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