Winter 2015 Midterm 4B

[Rhea Palsule]

In the problem, the volume is expanding from 3.3L to 9.2*10^5 L. However, when calculating the heat capacity for step 2, the solution says that volume is constant and C= 3/2(R). Shouldn't it be 5/2(R) because the pressure is constant?

[Jamlah Dalie 1K]

Since it doesn't state anywhere in the problem that the pressure is held constant while all this is happening, we can't assume it. So in the second part since we already accounted for the change in volume and we're accounting for the change in temperature now, we can assume that the volume is held constant, which is why we use 3/2 rather than 5/2.