"Burn Out! " Return to list of pracs

Aim: This activity is used to investigate what is required for a flame to keep burning.

Equipment:

• candle;
• matches;
• small clear glass jar.

Method: Place a small candle on the table and light it with the match. Have a discussion of what is required by the candle to maintain a flame (see Background Knowledge). Up turn the glass jar and place it over the candle until it goes out. Removing the factor of oxygen makes the candle go out. The same thing can happen if you cut the candle right down to its base and watch it burn out due to lack of flammable material.

Background Knowledge: A flame requires (a) flammable material (wick, wax), (b) an initial activation energy to start the flame; and (c) oxygen. The initial activation energy is the minimum amount of energy to create a high enough temperature to cause the match head to ignite. The energy comes from friction (the action of rubbing the match head on the rough side of the match box). You can extend this to cooking pancakes to demonstrate he formation of air bubbles within the pancakes and what might have happened within the oven.