Ice, water and steam are one substance
Ice cubes melt in a bowl. Put the bowl in a freezer. The water turns to ice again.
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The idea
Step 1 of 4
- 200 g of ice, cold.
- Warmed up. It melts to water. Still 200 g.
- Warmed more. It boils to steam. Still 200 g.
- Cooled again. Steam, water, ice — one substance, three forms.
The rule
Ice, water and steam are one substance in three forms. The weight stays the same. This holds only if no steam escapes, as in a closed pot.
Condensing is steam turning back to water.
Melting, freezing, boiling and condensing only change the form. Each one is a physical change.
| Stage | Weighing scale |
|---|---|
| Ice | 200 g |
| Water | 200 g |
| Steam | 200 g |
Watch out!
A lit flame does not mean the thermometer keeps rising. While ice melts, the temperature stays at 0 °C. The heat is changing the form.