Apparatus:

• A known mass of the liquid
• A calorimeter (e.g., a Styrofoam cup inside a beaker)
• A thermometer (capable of measuring to 0.1°C)
• A hot plate or Bunsen burner
• A balance
• A beaker of water (for the calorimeter)

Procedure:

1. Weigh the liquid and record its mass (m).
2. Measure the mass of water in the calorimeter and record it.
3. Heat the liquid in a separate container on the hot plate or using the Bunsen burner until it reaches a known high temperature (T_hot). Monitor the temperature with the thermometer.
4. Quickly transfer the hot liquid into the calorimeter containing the measured mass of water.
5. Stir the water gently and monitor the temperature of the water and the liquid mixture.
6. Record the maximum temperature reached by the water-liquid mixture (T_final).

Calculation:

Assuming no heat is lost to the surroundings, the heat lost by the liquid is equal to the heat gained by the water and the calorimeter. The heat gained by the water is calculated as: Q = m_water × c_water × (T_final - T_initial), where c_water is the specific heat capacity of water (4.18 J/g°C) and T_initial is the initial temperature of the water. The heat gained by the calorimeter is calculated as: Q_calorimeter = m_calorimeter × c_calorimeter × (T_final - T_initial), where c_calorimeter is the specific heat capacity of the calorimeter material. The heat lost by the liquid is calculated as: Q_liquid = m × c_liquid × (T_hot - T_final), where c_liquid is the specific heat capacity of the liquid (the value we want to determine). Equating heat lost and heat gained and rearranging gives: c_liquid = (m × (T_hot - T_final)) / (m_water × c_water × (T_final - T_initial) + m_calorimeter × c_calorimeter × (T_final - T_initial)).

Source of Error 1: Heat Loss to the Surroundings.

Minimising Error: Insulate the calorimeter and the experimental setup to reduce heat exchange with the environment. This can be achieved by using a well-insulated calorimeter (e.g., a double-walled calorimeter) and wrapping the entire setup in insulating material.

Source of Error 2: Incomplete Heat Transfer.

Minimising Error: Ensure the solid or liquid is fully immersed in the calorimeter and that the mixture is stirred continuously to promote uniform temperature distribution. Allow sufficient time for the system to reach thermal equilibrium before recording the final temperature.

When the iron block is heated from 20°C to 80°C, the average kinetic energy of the iron atoms increases. This is because the heater provides energy to the atoms, causing them to vibrate with greater amplitude and move with higher speeds. The kinetic theory states that the average kinetic energy of the atoms is directly proportional to the absolute temperature. Therefore, as the temperature increases, the average kinetic energy of the atoms also increases.

The observed change in the material's temperature is a direct consequence of this increase in average kinetic energy. Temperature is a macroscopic measure of the average kinetic energy of the particles within a substance. The higher the average kinetic energy of the iron atoms, the higher the temperature of the iron block. The increased kinetic energy allows the atoms to overcome their intermolecular forces more readily, leading to expansion and the perceived increase in temperature.