Lesson 8 of 19
One candle, two changes at once
Show on a big screenA candle is lit. A pool of clear wax forms around the wick, the candle's thread.
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The idea
Wax vapour is wax as a gas.
Step 1 of 4
- Candle lit. Wax melts near the wick.
- The pool of melted wax grows.
- Hot wax turns to vapour. The vapour burns.
- Blown out. The pool sets hard again. The burned wax does not return.
The rule
Wax melting is physical. Wax vapour burning is chemical. A candle has both.
| Step | Kind of change |
|---|---|
| Solid wax melts | Physical |
| Melted wax climbs the wick | Physical |
| Hot wax turns to vapour | Physical |
| The vapour burns | Chemical |
| The pool sets hard again | Physical |
Melting comes first. Without melting, the wax cannot reach the flame.
Try the lab to finish this lesson.