The Non-Candle

Description

Materials that look and burn very much like an ordinary candle are used to illustrate the effects which one's experience and expectations have upon the observations they make.

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1. Watch the movie. Make detailed observations of the burning.
2. Sketch and label a diagram of what you observed.

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Name ___________________________ Class ________

Teacher__________________________

DoChem 008 The Non-Candle

1. Watch the movie and record your observations detail.
2. Make of labeled sketch of what you saw.

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Purpose

To illustrate the difficulty in making unbiased observations.

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• potato (large apple)
• Brazil nut
• 2-cm cork borer (apple corer)
• single edge razor blade
• match
• plate (Petri dish)
• darkened room (dim lighting must be possible)
• nail (dull ice pick)

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• The success of this demonstration depends upon creating an illusion that you are working with an ordinary candle. The room must be darkened. You may use an apple in place of a potato. If more than three minutes will elapse between the time the apple is cut and the presentation of the experiment, the outside of the apple will need to be treated with lemon juice to prevent darkening.
• Other nuts (e.g., almonds) may be used in place of Brazil nuts. It is easy to produce a 'non-wick' for the 'non-candle' using a nut which may be cut into long slivers.
• Some teachers eat the 'candle.' It is debatable as to whether or not this is a good practice. Raw apples are easier to ingest than raw potatoes.
• The demonstration is usually performed by having the teacher leave the room while turning off the lights on the way out; lighting the 'non-candle'; and returning carrying the lighted 'non-candle.' Students must make their observations from the light of the 'non-candle.'

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Teacher set-up: 10 minutes

Presentation: 15-20 minutes

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• The match and burning material can cause fires and burn injuries.
• The razor and the cork borer (apple corer) can cause cuts.

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• Keep a fire extinguisher nearby.
• Use caution with the razor. Use caution with the cork borer (apple corer).

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The materials may be disposed of with ordinary solid waste. Wrap the used razor blades carefully before discarding so that janitorial personnel will not be injured.

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1. Use a razor blade to cut a piece of Brazil nut approximately 3 mm x 3 mm x 3 cm
2. Cut the ends from a 10 cm potato forming parallel faces.
3. Place the potato on one of its cut faces on a cutting surface. Use a cork borer or apple corer to cut a cylindrical piece of material.
4. Place the cylinder on a dish. Use a long pointed object (a nail; the tang of a file) to put a hole in the cylinder. Insert the sliver of Brazil nut into the hole.
5. Light the 'non-candle.' Bring the lighted candle into a darkened room where the students are waiting.
6. Ask students to make observations while the 'non-candle' burns. Blow out the 'non-candle' after about 2 minutes.

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Once the 'non-candle' is out you may turn on the lights, ask the students to make more observations, and begin a discussion of the observation process. For example, the 'dripping wax' that students often report seeing as the 'non-candle' burns is never found during the observation in full light. This leads to a discussion of "if you didn't really see it, why did you report it?"

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• discrepant event
• candle
• flame
• burning
• combustion

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