Relevant Resource questions :

Concepts demonstrated :

• Ignition temperature

Equipment needed :

• Plastic drink container/bottle (250 ml or 375 ml) filled with twice as much H2 as O2
• small candle and matches
• filter funnel holder and retort stand

• Mount bottle filled with gas upside down loosely in filter funnel holder.
• Place lit candle below the bottle to slowly heat the gas.

Physics involved :

The demonstration shows that you do not need a flare to get gases to ignite. When the mixture of gases reaches ignition temperature they ignite, producing an explosion which launches the plastic bottle into the air.

How to use the Demonstration :

• Set up the demonstration as students enter the lecture theatre.
• Show them the demonstration, describe it (gases in bottle etc.), discuss ignition temperature and then continue with lecture.
• Gases may take between 20 minutes and 40 minutes to ignite - it will wake up the lecture room !

• Matches on a match box: the match head ignites because the friction produced between the head and the box heats the head above the ignition temperature of the material in the head (phosphor ? etc ?).

• Make the whole demonstration.

• A good attention-grabbing demonstration.