To a sample of water at 23.4oC in a constant pressure calorimeter of negligible heat capacity is added a 12.1 g piece of aluminium whose temperature is 81.7oC. If the final temperature of water is 24.9 oC, calculate the mass of the water in the calorimeter.

We use heat balance to answer the following problem. The heat absorbed by water is equal to the heat released by alumimum object. The heat capacity of aluminum is 0.92 J/g C and of water is 4.186 J/g °C. The heat balance is as follows:

mass water * 4.186 J/g C * (24.9 - 23.4) C = 12.1 g * 0.92 J / g C * (81.7 - 24. 9) C mass water = 100. 70 grams