Rising water

This experiment requires the assistance of an adult.

For this experiment, you’ll need a bowl, tape, some water, a glass (that’s taller than the candle) and a candle (that must be handled only by an adult).

We begin by applying some tape to the bottom of the candle and sticking it onto the centre of the bowl. Now fill the bowl with water until the water is about an inch or two in height.

Ask an adult to light the candle. Place the glass over the candle and watch what happens inside the glass.

Can you see the water rise in the glass?

This occurs because of a few events. The candle’s flame uses up the oxygen in the air inside the glass as it burns, however, the flame also heats up the air and the air expands. The space consumed by the expanded molecules of air is almost equal to the space made available from the consumed oxygen and no change takes place in the level of the water in the glass. When the candle goes out, the air cools down and the air contracts, this makes a vacuum and the water quickly rushes in to fill up the space available.

There’s a quick demonstration of this experiment performed by Sick Science!, here it is:

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