Question

What do you mean by change of state of matter? Explain the change of a solid into a liquid at a constant temperature.

Answer 1

• The change from one state of matter to another by absorbing/releasing heat energy is known as change of state.
• The process of change of a substance from solid state into its liquid state on absorption of heat at a particular temperature, called the melting point, is called melting or fusion.
• The heat energy absorbed by the substance increases the amplitude of vibrations of the molecules of the solids and a state is reached at the melting point when the molecules acquire sufficient energy to overcome the force of attraction between them and they become free to move. The solid thus changes into a liquid.