Question

How will you determine the specific heat of a metal using a calorimeter? 

OR 

Describe the experiment to determine the specific heat of iron using an iron ball, calorimeter and water.

Answer 1

1. Find the mass (m_i) of the iron ball.

2. Find the total mass (m_c) of the calorimeter (metal container) and the stirrer.

3. Fill the calorimeter to two-thirds of its capacity with water and find its mass (m’_c) along with the stirrer. Hence, find the mass (m_w) of the water in the calorimeter (m_w = m’_c – m_c).

4. Keep the calorimeter in the wooden box and note the temperature (T₁) of the water in the calorimeter with the thermometer.

5. Suspend the iron ball in water in a beaker. Heat the beaker so that the water starts boiling. Note the temperature (T₂) of the boiling water. 

6. Transfer the iron ball quickly to the calorimeter and cover the calorimeter with the lid immediately.

7. Stir the water in the calorimeter gently and continuously for uniformity of temperature and note the maximum temperature (T₃) attained by the mixture.

8. Find the specific heat capacity of iron using the following formula: heat lost by the iron ball = heat gained by the calorimeter, stirrer and water [assuming that there is no exchange of heat between the system (calorimeter, stirrer, water and iron ball) and the surroundings].

∴ m_iC_i (T₂ - T₃) = (m_cC_c + m_wC_w) (T₃ - T₁)

∴ C_i = \(\cfrac{(m_cC_c + m_wC_w) (T_3 - T_1)}{m_i(T_2-T_3)}\)

where cc = specific heat of the material of the calorimeter and stirrer and c_w = specific heat of water. 

Hence, the specific heat of iron (c_i) can be determined when other quantities are known.