Question

16. Consider two boxes that are separated. Both boxes are 1-m3. The first box is filled with 1 mole of N2 at 100K and the second box is filled with 1 mole of Ar at 200K. The two boxes are placed into contact so heat can transfer between them. What is the final temperature?

a. 137.5 K b. 150.0 K c. 162.5 K

17. Now suppose the wall between the two boxes is removed after they have equilibrated. What is the change in the total entropy before and after removing the partition?

a. 11.5 J/K b. 23.1 J/K c. 5.76 J/K

Answer 1

16. Considering that the heat capacity at constant volume for monoatomic gasses is 2/3R and the heat capacity for diatomic gasses is 5/2R, that the molar weight of N₂ is 28g/mol and the molar weight of Ar is 40g/mol approx, we can write:

17. The entropy of mixing of the two gasses is given by: