Two ideal gases, nA moles of A and nB moles of B, initially occupy distinct volumes VA and VB at different temperatures, TA and TB. The molar heat capacities at constant pressure are CA and CB. A and B are combined to make a total volume VA + VB at equilibrium. First write an equation for the total S of this process in terms of the parameters above and the final temperature Tf . then find the equation for Tf .