Starter: Write in your books or A4 colour paper. Title: Explaining the Energy to Evaporate a Liquid Use your memory or research how to build a picture of the energy changes when substances change state. 10 minutes allowed – be ready to feed-back Challenge: draw boxes of particles to accurately represent these states of matter and describe the energy of their movement. Super challenge: add arrows to the diagram to show freezing, melting, evaporation and condensation. 3. Super-duper challenge: describe the energy changes involved to make each change in state happen. Write the equation to calculate the change in energy to evaporate a liquid (latent heat of vaporisation.) SOLID LIQUID GAS

Check you have included these ideas: Solids have relatively low energy of movement – particles vibrate. Liquids particles have more energy and are able to flow around each other in a random way. Gas particles are completely free to move around freely and randomly. Melting and evaporation involve transferring energy to the substance. Freezing and condensation involve transferring energy away from the substance. Energy required to evaporate a liquid = m x L (L = latent heat of evaporation – the energy required to evaporate one kilogram of a substance; m = mass evaporated) Melting Evaporation Freezing Condensation