1. The problem statement, all variables and given/known data An isolated box contains two chambers seperated by a thermally insulating but moveable partition. Both chambers contain dilute gas (same kind) at different densities and temperatures. The left chamber contains 1.0 x 10^22 particles at 25 degrees celsius and the right chamber 6.0 x 10 ^21 particles at 15 degrees celsius. What is the equilibrium temp when the wall is removed? 2. Relevant equations PV=NkT [Left Chamber] (mCv(Tf-Ti)) + [Right chamber](mCv(Tf-Ti)) Maybe the density equation? 3. The attempt at a solution What I understand; - The volume is constant - Chamber left loses some energy this is the same as what chamber right gains - The Heat capacity is the same as the gas is the same in both chambers so we can forget it. So I've tried all sorts of things but the problem is I don't know get how the number of particles can be exchanged for a mass seeing as we don't know which type of gas it is, otherwise the problem would be easy right? Just solve for Tf. Should I just use a random gas and get the molar mass etc. or is there a better way?