Describe an experiment to demonstrate that water absorbs heat during boiling at a constant temperature.

The following experiment demonstrates that water absorbs heat during boiling at a constant temperature —

1. Take a beaker and pour some water in it.
2. Place the beaker on a wire gauze placed over a tripod stand.
3. Clamp a thermometer in a vertical stand and insert it in the beaker.
4. Heat the beaker over the flame of a burner.
5. Record the temperature of water after every minute.

Observation — The temperature of water gradually rises and when it reaches 100°C, water starts boiling. Once the water starts boiling, its temperature does not rise any further, although heat is still being supplied.

Conclusion — From the above experiment we can conclude that, at 100°C water begins to boil and changes into steam by absorbing the heat being supplied to it without further rise in temperature.