Question

A caloriemeter contains 0.2kg of water at 30⁰C. 0.1 kg of water at 60⁰C is added to it, the mixture is well stirred and the resulting temperature is found to be 35⁰C. The thermal capacity of the caloriemeter is

• A. 6300 J/K
• B. 1260 J/K
• C. 4200 J/K
• D. None of these

Answer 1

Answer: (B)

1260 J/K

Answer 2

Let X be the thermal capacity of calorimeter and specific heat of water = 4200 J/kg-K

Heat lost by 0.1 kg of water = Heat gained by water in calorimeter + Heat gained by calorimeter

⇒ $0.1 \times 4200 \times (60 - 35) = 0.2 \times 4200 \times (35 - 30) + X(35 - 30)$ 10500 = 4200 + 5X ⇒ X = 1260 J/K