# Homework Help: Isotherm, Isobaric, and Isochoric Problem

1. Jan 16, 2008

### physics4u

1. The problem statement, all variables and given/known data

One mole of a monatomic ideal gas has an initial pressure, volume, and temperature of Po, Vo, and 442 K, respectively. It undergoes an isothermal expansion that triples the volume of the gas. Then the gas undergoes an isobaric compression back to its original volume. Finally the gas undergoes an isochoric increase in pressure, so that the final pressure, volume and temperature are Po, Vo, and 442 K, respectively.

Find the total heat for this 3-step process?

2. Relevant equations
W=nRTln(Vf/Vi)

3. The attempt at a solution

For the first part of this question I used w=nRTln(Vf/Vi) and thats how I would find my Q(heat) for the isotherm b/c Q=W since temp is constant. But since Volume is not given to us, and it says the volume triples I just put in the value for 3 in volume and i ended up with 4037J

The second part of the problem for Isobaric I dont know how to solve. Because the eqn I was planning on using is W=P(Vf-Vi) but since there was no volume given I wasn't able to solve for this problem. So how do I solve for Q for the Isobaric?

For the third part, the Isochoric, I just used 3/2nRT and I ended up with 5512.2J.

I know I should be adding all the Q's(Q1+Q2+Q3) to get my total heat but how do I solve for Heat for the Isobaric part, when I am not given volume or pressure?