Both evaporation and boiling will cause a change of state from a liquid to a gas. However, they take place slightly differently.
In a liquid, some particles have more energy than others. The particles with the most energy leave the surface, spread out and form a gas. This is called evaporation. The liquid does not bubble and evaporation happens at all temperatures.
For example, on a rainy day puddles form. When the Sun comes out, the puddles dry up. This is due to evaporation. The water particles at the surface of the puddle gain enough energy to escape as gases.
Evaporation Boiling
9.3
z
In the case of boiling, all particles in the liquid are involved – they all have enough energy to break free. The temperature at which a liquid changes to a gas is called the boiling point. The boiling point of water is 100 °C.
Evaporation is slower than boiling, but the overall result of a liquid changing to a gas is the same.
Hanging out the washing
In good weather, washed clothes can be hung outside to dry. For wet washing to dry, the liquid water particles need to be changed to gas particles and be moved away from the washing.
Use diagrams to explain why washing dries more quickly on a warm and windy day.
