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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.
Solution
(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
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