Prelab Assignment Experiment 10: Answers
1. Define specific heat capacity.
The amount of heat required to raise the temperature of 1 g of material by 1K.
2. What is the specific heat of iron if it takes 186 J of heat to raise the temperature of 165g of
iron from 23.2oC to 25.7oC?
Divide the total heat absorbed by the number of grams of iron (to get a value per gram) and
also by the temperature rise (to get a value per degree) = 186/(165 x 2.5) = 0.451 J g-1 K-1
3. An experiment was performed to determine the heat capacity of a coffee cup calorimeter.
To 100ml of water at 22.4oC was added 100ml of water at a temperature of 38.6oC. The final
temperature was 30.2 oC. Calculate the heat capacity of the calorimeter, assuming the
density of water to be 1.0 g cm-3 and its specific heat to be 4.18 J g-1.
Heat lost by the hot water is T x wt x specific heat = 8.4 x 100 x 4.18 = 3511 J
Heat gained by cold water is T x wt x specific heat = 7.8 x 100 x 4.18 = 3260 J
We note that more heat has been lost by the hot water than has been gained by the cold
water. The "missing" heat was used to warm up the calorimeter.
T for the calorimeter is 7.8oC as it started off at the same temperature as the cold water. Its
temperature was raised this amount by absorbing 3511 - 3260 = 251 J of energy, so the
heat capacity of the calorimeter (the amount of heat needed to raise its temperature by 1
degree) is 251/7.8 = 32.2 J K-1