The science of nutrition and healthy eating
The science of nutrition and healthy eating

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The science of nutrition and healthy eating

1.2 How many kilocalories in a peanut?

If you can do the following experiment, you should get a rough idea about how many kilocalories there are in a peanut.

This experiment involves burning a peanut, so you need to take the appropriate precautions. If necessary, ask someone to help you. It is probably best done outside on a calm day because quite a lot of smoke might be produced. If you cannot do this experiment, you might still be able to follow the ideas and try the calculations.

Activity 1 Measuring energy in food

Timing: Allow approximately 45 minutes.

Equipment and materials

  • a peanut – ideally the fresh ones you can buy in their shells or for feeding to birds. These work much better than salted peanuts
  • a cork
  • a sewing needle
  • some aluminium foil
  • an old metal tablespoon
  • some water
  • a lighter or matches.

Method

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Push a needle into a cork
Mount a peanut
Fill a tablespoon with water
Ignite the peanut
Heat the water
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  1. Push the eye of the sewing needle carefully into the end of the cork, and spike the peanut onto the sharp end. This will allow you to hold the peanut while it burns, so you don’t burn your fingers.
  2. Place some aluminium foil underneath where you will burn the peanut, so that bits falling off the peanut won’t cause any damage.
  3. Fill the tablespoon with water and set it to one side. This is the equivalent of the jacket of water around the bomb calorimeter.
  4. Use a lighter or a match to set the peanut alight. This may take a few attempts.
  5. Once the peanut is burning steadily, hold the spoonful of water over it. Watch carefully to see if you can get the water hot enough for it to boil.

Remember that everything will get hot once your peanut is alight. Please be careful!

So, can you use a peanut to boil your tablespoon of water?

SNHE_1

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