Question

Define the process of change of a liquid to a gas.

Answer 1

Step 1: Change of state

On heating, the molecules of matter move rapidly and expand. Due to their continuous movement, while heating, they change from one state to another. This is known as a change of state of matter.

Step 2: Change a liquid to gas

• The process in which the liquid absorbs heat and changes into the gaseous state is called vapourisation. There are two ways in which a liquid changes into its gaseous state - evaporation,and boiling.
• The slow and gradual conversion of a liquid into its gaseous state at all temperatures is called evaporation and it occurs on the surface of the liquid. Example: Drying of the floor after it is mopped
• The process in which a liquid rapidly changes into a gaseous state at a constant temperature is called boiling. The constant temperature at which the liquid boils is called the boiling point. It takes place throughout the liquid. Example: Boiling of water.

Therefore, the change of state from liquid to gas is called Vapourisation.