1. The problem statement, all variables and given/known data Consider a well-insulated horizontal rigid cylinder that is divided into two compartments by a piston that is free to move but does not allow gas to leak into the other side. Initially, one side of the piston contains 1 cubic meter of Nitrogen (N2) at 500 kPa and 80 degrees centigrade while the other side contains 1 cubic meter of Helium (He) gas at 500 kPa and 25 degrees centigrade. Now thermal equilibrium is established in the cylinder as a result of heat transfer through the piston. Using constant specific heats at room temperature, determine the final equilibrium temperature in the cylinder. What would your answer be if the piston were not free to move? N2 V = 1 m3 P = 500kPa T = 80 C He V = 1 m3 P = 500kPa T = 25 C 2. Relevant equations PV = mRT Q = m(T2-T1)Cp 3. The attempt at a solution I used the specific heat at constant pressure to solve the first part of the problem (Cp) Cp N2 = 1.039 Cp He = 5.1926 Using the ideal gas law i found the mass (kg) of each gas m = (PV) / (RT) m N2 = 4.77 kg m He = 0.807 kg then using the energy from one side of the cylinder equal to the other to find the final temperature of the system Q N2 = Q He (4.77)(T2-80)(1.039) = (0.808)(T2-25)(5.1926) I get T2 = 384K or 111 C This answer seems too high to be correct (it is higher than the initial temp of both gases) If someone could point out were i'm going wrong that would be great.