Heat, melting and mixtures
Answers are for parents and teachers.
1
Draw three boxes of dots for water as ice, as liquid water and as water vapour. Say how the particles are arranged in each.
Ice: close together in a pattern. Liquid: close together but sliding past one another. Vapour: far apart and moving freely.
2
A cup of tea cools from 80 °C to 35 °C. By how many degrees did it cool? Do its particles move faster or slower now?
80 − 35 = 45 degrees. The particles move slower.
3
List five mixtures that you find at home. For each one name two of its parts.
Answers differ, for example: salad (tomato, cucumber); rice and lentils (rice, lentils); tea with sugar (water, sugar).
4
Explain why a puddle on a hot day gets smaller. Use the word evaporate.
The sun’s heat makes the water particles move faster, and the water evaporates into water vapour in the air.
5
Look at your bathroom mirror or a window after someone has a warm shower. Write what you see and explain it.
Tiny drops cover the cold glass. Warm water vapour touched the cold surface and condensed.