Science 6th grade | UNIT 3: Material changes 3.1 Reversible and irreversible changes booklet
Science 6th grade | UNIT 3: Material changes 3.1 Reversible and irreversible changes booklet
- Unit 1: The human body
- Unit 2: Materials: properties and changes
- Unit 3: Rocks, the rock cycle and soil
- Unit 4: Food chains and food webs
- Unit 5: Forces and electricity
- Unit 6: Light and the solar system
Reversible changes
Activity 3.1 (Observing changes to ice)
You will need: ice cubes – saucer – watch
Place the ice cubes in the sun or other warm place for five minutes.
What has happened to the ice after five minutes?
What causes the ice to change?
What will happen to the ice if you put it back in the freezer? Why?
In a warm place the solid ice becomes liquid water. When you put the ice back in the freezer it becomes a solid again. We say that the changes are reversible because we can change solid ice back to liquid water and liquid water back to solid ice. Heat causes the ice to melt. When the water loses heat and cools it becomes solid again. This diagram shows phase changes between ice and water.
Irreversible changes
When some substances are heated, the changes cannot be reversed. We call these irreversible changes. Sometimes irreversible changes turn one substance into another substance. For example, when we burn a match the wood changes into a black substance called carbon.
?Can the match change back to the way it was
Questions
1) When you mix boiling water with jelly powder, the mixture is a liquid. In the fridge it becomes solid. Can we make jelly change back to a liquid? Draw a simple flow diagram to explain your answer.
2) a: Does boiling an egg cause a reversible or irreversible change? Explain why.
b: Does a new substance form when you boil an egg?
3: Think of an irreversible change that forms a new substance.
