One liter of helium at STP is heated at constant volume to 100 C. It is then allowed to mix in an insulated container with one liter of methane which is initially at STP, the final volume being two liters. The methane molecule has three rotational degrees of freedom. What is the final temperature? What is the increase in entropy? Compare your result with the entropy change that would occur if the gases were allowed to come into thermal equilibrium with each other, but not to mix.