# Urgent Isothermal process

1. Aug 16, 2009

### 101nancyma

Urgent!!!Isothermal process

Hi guys. i have a very short question. In an isothermal process, change is temperature is zero, so change in internal energy is zero, thus Q=W. The part that i am confused is that if Q=mc(deltaT) then should be a change in temperature in the isothermal process?
Thanks a lot

2. Aug 16, 2009

### bucher

Re: Urgent!!!Isothermal process

Q = mc(delta T) is not the correct equation in this example for the system. It has already been stated that Q must equal W in an isothermal process.

Think of it this way, if the system is a piston and the piston is drawn up then the system should cool. To keep the system at a constant temperature, the system is heated with the same energy that is extracted through work. Likewise, if the system is compressed then the system will have to expel heat to maintain its temperature.

If the system were in some kind of medium (air, water, etc) then the equation Q=mc(delta T) can be used for the surroundings.

Hope this helps.

3. Aug 16, 2009

### Count Iblis

Last edited by a moderator: Apr 24, 2017
4. Aug 16, 2009

### 101nancyma

Re: Urgent!!!Isothermal process

I totally understand now..thanks alot