120 g insulated aluminum cup at 13°C is filled with 140 g of water at 58°C. After a few minutes, equilibrium is reached. I found the final temperature to be 51°C. But I am having trouble finding the total change in entropy. I was using 13°C = 286.15°K 51°C = 324.15°K 58°C = 331.15°K ΔS = ΔS_cup + ΔS_water = Q_cup/T_avg + Q_water/T_avg = (MCΔT)_cup/T_avg + (MCΔT)_water/T_avg = (120g * 0.22 * (324.15°K - 286.15°K))/((324.15°K + 286.15°K)/2) + (140g * 1 * (324.15°K - 331.15°K))/((324.15°K + 331.15°K)/2) =0.296567 But I am told this is the wrong answer. What am I doing wrong here?