# Homework Help: Equilibrium temperature and Dulong-Petit law

1. Mar 7, 2010

### ChrisBaker8

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

A thermally insulated system consists of 1 mole of a diatomic ideal gas at 100K and 2 moles of a solid at 200K that are separated by a rigid insulating wall. Find the equilibrium temperature of the system after the insulating wall is removed, assuming the solid obeys the Dulong-Petit law. (Assume that the container is divided in such a way that there is no change in volume of the substances when the insulating wall is removed)

2. Relevant equations

c = 3R/M (D-P law)

Qv (gas) = 2.5 * R * $$\Delta$$T
Qp (gas) = 3.5 * R * $$\Delta$$T

c = C/m

c' = C/n

3. The attempt at a solution

I'm not sure how to start this without knowing what the substances are. Since there's no change in volume the changes are isochoric, therefore no work done, and the change in internal energy is equal to the heat added.

Last edited: Mar 7, 2010
2. Mar 9, 2010

### aim1732

The system is thermally insulated. How can heat be added?

3. Mar 10, 2010

### ChrisBaker8

...I didn't notice that part, that simplifies things. Thanks.