To measure the specific latent heat capacity of water by the electrical method.

Equipment needed:

  • Copper calorimeter
  • A stirrer, an insulating lid
  • Insulating material ( cotton wool )
  • A container
  • Heating coil
  • Thermometer
  • A D.C Power supply unit and connecting leads
  • A joulemeter and a balance

Method:

Find the mass of the empty calorimeter using a balance scales . ()

Then add sufficient water in the calorimeter to completely cover the heating coil.

Find the mass of the calorimeter and water.

Subtract the mass of the empty calorimeter from the mass of the calorimeter and water, to find the mass of the water added.(M

Place the calorimeter in the insulating material and set up the equipment.

Wait a minute or two then measure the temperature of the cold water and the calorimeter.(θ1)

The temperature of the water should be down to 7C below room temperature.

Switch on the current and the joulemeter. Ensure the joulemeter measures zero.

Allow the current to flow until the temperature is 7C above room temperature.

Stir the water with the stirrer all the way throughout the experiment to ensure the temperature is evenly distributed.

Then read the final temperature of the water and the calorimeter. Record the highest temperature θ2. Hence the rise in temperature is θ2 – θ1.

Read the final value on the joulemeter.

Preacautions:

  • Use a low specific heat digital thermometer
  • Use insulation around the calorimeter
  • Use a lid
  • Use a stirrer
  • Heat gently
  • Start 7C below room temperature so that any heat lost or gained in the surrounding is reciprocated.
  • Ensure the joulemeter measures zero.

Calculate the specific heat capacity of water using:

Heat lost=Heat Gained