## Heat and temp difference

AtreyiMitra2L
Posts: 169
Joined: Fri Sep 29, 2017 7:03 am
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### Heat and temp difference

Why is it that in isothermal, reversible expansion heat can be done if heat is defined as the transfer of energy due to a temperature difference? I understand that the change in internal energy must be 0 for ideal gases so heat must be involved but I dont understand it past this. Thanks!

Remi Lathrop 1G
Posts: 51
Joined: Fri Sep 29, 2017 7:07 am

### Re: Heat and temp difference

I'm not entirely sure what your question means, but for isothermal, reversible expansion of a gas we know that the gas is expanding at a constant temperature, therefore the system is doing work because the gas is expanding (changing volume). We know that work can be calculated by finding P∆V, so if there is change in volume there will be work done. While the system is doing work it is simultaneously losing energy, but this energy is replaced by heat flowing into the system from the surroundings.

The reaction is at constant temperature the whole time, but this constant temperature is achieved through an exchange of heat from the surroundings into the system. Hopefully this helps!

Julia Cheng 2J
Posts: 31
Joined: Thu Jul 13, 2017 3:00 am

### Re: Heat and temp difference

Isothermal just means that there's no change in temperature of the system, but there is still an exchange of heat between the system and the surroundings.