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8. Heat at work / Candle as "steam engine" Energy is "the capacity to do work or to cause a heat flow". (Zumdahl, Chemistry)
Work is a force over a distance. Force  is everything "pushing, pulling and lifting"(P.Warren, Physics for life). What you need: tray with water, candle as burner, micro spirit burner from a Liquemin bottle, matches, tissue paper, Liquemin bottle with a stopper,  "test tube holder": 15 cm insulated copper wire (2 x 0,6 mm), methylated spirit.
Experiment 1 (Photo 1):
Heat locked air  by a candle and by a micro spirit burner
1.  Stopper  an "empty" Liquemin bottle.
2. Twist the copper wire around it as a "test tube holder".
Photo 1:  Heat the bottle by the micro burner and after that by the candle. Observations?
You should learn from experiment 1:
The heat energy released by the chemical reaction of the spirit burner was transferred to the air locked in the bottle.
A pressure was produced inside the bottle. Photo 1: The pressure carried out work on the stopper transferring kinetic energy on it.
The heat energy released by the chemical reaction of the candle was not sufficient to move the stopper.
Wax was transformed into soot.
Experiment 2 (Photo 2, 3):
Heat locked water drops  by a candle
1.  Heat water drops on the bottom of a closed Liquemin bottle  by a candle.
2. Heat the upper part of the bottle. (Photo 2)
Photo 3: Observe, what happens with the stopper, the bottle and the flame.
You should learn from experiment:
Water drops are evaporated by the heat of the candle. Water vapour condensed in the upper part of the bottle.
The water vapour produced by the candle light carried out work on the stopper:
It moves forward, while the vial is pushed into the opposite direction.

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