Heat and change of physical state - Concept of Boiling (Vaporization)

Boiling is the process where a liquid turns into vapour when it reaches a specific temperature called the boiling point. At this point, bubbles form throughout the liquid, and it changes to gas rapidly.

• When you heat water on a stove, its temperature increases and it starts evaporating faster.
• As the water gets hotter, bubbles of water vapour form and rise to the surface. This is called the boiling of water.
• When water reaches a specific temperature, it starts boiling rapidly. For pure water, this happens at 100 °C at sea level, which is called the boiling point of water.
• At this point, evaporation happens throughout the entire body of water, not just at the surface. The water bubbles and turns into steam that rises into the air.

Boiling

Water naturally evaporates all the time, even without heating. For example, when water is spilt on the floor, it dries up slowly because it evaporates from the surface. Evaporation occurs from the surface of the water, and it’s a slow process.

When water vapour (steam) cools, it turns into liquid water. This process is called condensation. Interestingly, condensation occurs at the same temperature as boiling-100°C. So, the temperature at which water boils and the temperature at which it condenses are the same.