6 (a) An electric kettle contains 1.41 kg of water at 25°C - Edexcel - GCSE Physics Combined Science - Question 6 - 2021 - Paper 1

For the specific latent heat of vaporisation, we use the formula:

Where:

• $L$ is the specific latent heat of vaporisation (J/kg)
• $Q$ is the thermal energy supplied (J)
• $m$ is the mass of the water that has evaporated (kg)

Given:

• $Q = 450000$ J
• $m = 1.41 - 1.21 = 0.2$ kg

Substituting the numbers:

Thus, the specific latent heat of vaporisation of water is 2250000 J/kg.

To determine the specific heat capacity of aluminium, the student could follow these steps:

1. Measure the temperature of the boiling water:

   • Use a thermometer to accurately measure and record the boiling point of the water.

2. Allow sufficient time for the block to reach temperature of boiling water:

   • Place the aluminium block in the boiling water for a sufficient period to ensure it reaches equilibrium temperature with the water.

3. Measure temperature of cold water:

   • Before transferring the block, measure the initial temperature of the cold water using a thermometer.

4. Transfer the aluminium block to the cold water:

   • Using the piece of string, carefully transfer the hot aluminium block to the beaker of cold water without loss of heat.

5. Record temperature changes:

   • Continuously monitor the temperature of the cold water until it stabilizes. Record the final temperature of the cold water.

6. Calculate the specific heat capacity of aluminium:

   • Use the formula:
   $$Q_{lost} = Q_{gained}$$

   to find the heat transferred. Calculate the heat lost by the aluminium block using:

   $$m_{Al} imes c_{Al} imes (T_{initial} - T_{final}) = m_{water} imes c_{water} imes (T_{final} - T_{initial, cold})$$

The specific heat capacity $c_{Al}$ can then be solved, rearranging as needed based on the measurements taken.