Purpose
To illustrate a combustion reaction.

Materials

• Rubbing alcohol (70% isopropyl alcohol)
• 19 L plastic water bottle (water cooler jug)
• Meter stick with candle on the end (or barbeque lighter)
• Safety shield
• 50 mL graduated cylinder

Safety and Disposal

• Read the MSDS/WHMIS sheets for all chemicals before using them
• Wear chemical safety glasses
• Safety shield should be between the bottle and the audience
• Ensure you are one meter away when using the meter stick/candle to start the reaction
• Never heat the bottle above room temperature prior to use
• Never flush the bottle with oxygen prior to use

Procedure

1. Add 50 mL of rubbing alcohol to an empty 19 L plastic water bottle.
2. Swirl the alcohol around to coat the inside of the container.
3. Pour out the excess alcohol and remove it from the demonstration area.
4. Place bottle behind a safety shield.
5. Dim the lights.
6. Light a candle on the end of meter stick and then place the flame over the mouth of the bottle.

Results

• A blue, horizontal circle of flame should form and move from the top of the bottle to the bottom.
• A “whoosh” sound is heard.

Follow-up Teaching Notes
A “whoosh” sound is generated as the gases in the bottle expand out of the container as they are heated from the rapid exothermic combustion reaction.

Concept
combustion, expansion of gases.

Extension

• Place the palm of your hand over opening of the bottle after the combustion ends, as the bottle cools the resulting pressure decrease causes the bottle to stick to your hand.
• A second “whoosh” may be heard as air rushes back into the bottle as you remove your hand.

Disposal/Clean-up
The plastic container can be stored for reuse if the are no visible signs of stress or damage to the container.

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