Science Unit 6D: Reversible and irreversible changes
Mixing materials with water
Learning objective: mixing materials can cause them to change.
When we make changes to materials by dissolving them in water we can sometimes reverse the change. For example, adding salt to water can be reversed by evaporation. Some materials react with water (chemical reaction) to make a new material. For example, a new material (concrete) is made by mixing cement with water. You cannot get the cement back once it has been mixed with the water. Other solids may react with the water to produce a gas which escapes as bubbles.
If we can change the material back it is called a reversible change, if we cannot change the material back it is called an irreversible change.
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