Spontaneous Combustion

Purpose:

This demonstration will allow you to light two different candles because of a redox reaction.

Materials:

• 2candles

• ethyl alcohol
• CrO₃
• mortar and pestle

Procedure:

1. Grind 0.5 grams of CrO₃ with a mortar and pestle.

2. Pinch as much as possible on a candle wick.
3. Soak the other candle wick in ethyl alcohol.
4. Touch the two candles together and they will spontaneously ignite.

Discussion:

The ethyl alcohol is oxidized by the reduction of chromium (+6) to chromium (+3).

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