Question

A copper calorimeter of mass 50g contains 100g of water at 20°C. A metallic piece of mass 250 g is heated to 100°C and is then dropped into the calorimeter. The contents of the calorimeter are well stirred and its final highest temperature is recorded to be 28 °C. If the specific heat capacity of water is 4.2 J/g°C and of copper is 0.4 J/g°C, find:
(i) the heat gained by water,
(ii) the heat gained by calorimeter,
(iii) total heat supplied by the metal piece, and
(iv) the specific heat capacity of metal.

Answer 1

(i) Heat gained by water = Mass of water × Specific heat capacity of water × Rise in temperature

= 100 × 4.2 × (28° - 20°) = 3360 J

(ii) Heat gained by calorimeter Mass of calorimeter × Specific heat capacity of copper × Rise in temperature

= 50 × 0.4 × (28 - 20) = 160 J

(iii) Total heat supplied by the metal piece = 3360 + 160 = 3520 J

(iv) If the specific heat capacity of metal is c, then Heat supplied by the metal piece

= Mass × Specific heat capacity × Fall in temperature

or  3520 = 250 × c × (100° - 18°)

or c = `3520/(250 xx 72) = 0.195` J/g °C