Next time it rains, look at the puddles left behind. Shallow puddles disappear quickly while deeper ones stay around longer. You’re watching evaporation in action.
Evaporation is the process where a liquid changes to a gas. It happens when single particles at the surface of a liquid have enough energy to break away from the other particles.
- Evaporation can happen at any temperature, unlike boiling, which only happens at the boiling point.
- The higher the temperature, the faster the evaporation.
- Some substances evaporate easily, some evaporate very little. It depends on the strength of the forces between particles.
This infographic is designed to be displayed as a poster in the classroom, although it can also be displayed on a projector or printed out as a handout.
Use the accompanying fact sheet and practical worksheet to explore evaporation and develop your students’ skills.
In the bathroom
When you take a shower or bath, the hot water evaporates and produces lots of water vapour. You can see the water as it condenses on cooler surfaces like windows and mirrors.
In a pandemic
Surface cleaning is important to prevent us picking up viruses from contaminated surfaces. When you spray door handles and other commonly touched surfaces with disinfectant, they don’t stay damp for long.
The layer of liquid evaporates quickly because it’s very thin and has a high surface area so more of the particles in the liquid are in contact with the air.
Hand hygiene has become more important during the pandemic. Next time you use an alcohol-based hand gel, rub the gel all over and give your hands a good shake – how do they feel?
In the kitchen
When a loaf of bread is baking, the inviting smell is due to evaporation of flavour compounds with complex names, such as 2-acetyl-1-pyrroline, that diffuse around the house.
And if you fancy some coffee with your toast, you’ll enjoy the aroma of 2-furylmethanethiol, among others.
All illustrations© Dan Bright