A test for something new
Blow air through a straw into lime water, a clear test liquid. It turns milky, a cloudy white.
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The idea
Step 1 of 4
- Two glasses. Tap water and lime water.
- Blow air into each one through a straw.
- Tap water: bubbles only. It stays clear.
- Lime water: it turns milky. A white solid forms.
A chemical change makes one or more new substances. The process is a chemical reaction.
Your breath has carbon dioxide. The carbon dioxide reacts with lime water. The new white solid makes the water milky.
Lime water + carbon dioxide → calcium carbonate (white solid) + water
The rule
A chemical change makes a new substance. Lime water turning milky shows carbon dioxide.
Vinegar and baking soda fizz. The gas is carbon dioxide too, a new substance. So that is a chemical change. Chalk and washing soda fizz in vinegar too.
Your teacher may show these tests. Do not try them at home.