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

We can use the formula for specific latent heat:

$$dQ = m imes L$$

where:

• $dQ$ is the thermal energy supplied (450000 J)
• $m$ is the mass of water that evaporated (1.41 kg - 1.21 kg)
• $L$ is the specific latent heat of vaporisation

First, we calculate the mass of evaporated water:

$$m = 1.41 - 1.21 = 0.20 ext{ kg}$$

Now substituting:

$$450000 = 0.20 imes L$$

Rearranging gives us:

L = rac{450000}{0.20} = 2250000 ext{ J/kg}

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

To accurately determine the specific heat capacity of aluminium, the student should:

• Measure the temperature of the boiling water using a thermometer.
• Allow sufficient time for the aluminium block to reach the temperature of the boiling water.
• Measure the temperature of the cold water before transferring the aluminium block into it.

After transferring the aluminium block to the cold water, the student should:

• Stir to ensure even distribution of temperature.
• Measure the maximum temperature reached by the cold water after adding the aluminium block.
• Calculate the temperature change of both the cold water and the aluminium block. Using these measurements, apply the energy balance equations to find the specific heat capacity of aluminium.