kitchen science experiments

Watch in awe as you grow your own edible, crunchy, candy crystals – the longer you leave them, the bigger they grow!

Scientific Principle: Saturation
Time Required: 3-7 days

Ingredients

  • 1 cup of water
  • 2-3 cups of sugar
  • Food colouring

Equipment

  • Wooden skewer
  • Clothes peg
  • Saucepan
  • Tall, narrow, clean glass or jar

Method

  1. Heat the water in a saucepan over a low heat until it is simmering.
  2. Slowly add the sugar, stirring constantly, making sure that the sugar dissolves in the water before adding more.
  3. Keep adding the sugar until the water starts to look cloudy. This is the point where no more sugar will dissolve.
  4. Remove the pan from the heat and allow to cool.
  5. Wet the skewers with water, then roll them in the remaining sugar – leave for a few minutes to dry.
  6. Once the sugar solution has cooled, pour it into the glass or jar and add food colouring.
  7. Clip the clothes peg onto the wooden skewer so that the skewer is suspended in the centre of the glass and is approximately 2 cm (1 inch) from the bottom of the glass.
  8. Leave the glass on a table where it will not be knocked and watch it grow.
  9. The first crystals should form after 3 days and will continue to grow bigger.
  10. You can help your candy crystals to grow by checking for, and removing, any crusty film that forms on the surface of the solution.
  11. When you are happy with the size of your candy crystal, remove it from the solution and leave it out to dry for a couple of hours before eating.

THE SCIENCE BEHIND CANDY CRYSTALS

If you pour a spoonful of sugar into a glass of cold water and stir it, the sugar will dissolve into the water. If you keep adding sugar to the water it will stop dissolving. However, if the water is heated, more sugar can be forced to dissolve in the water, creating what is called a supersaturated solution. As the water cools back down, the supersaturated solution becomes unstable since it contains more sugar than it can hold. The sugar then starts to
come out of the solution and reforms as solid sugar crystals. The more the sugar solution cools, the more sugar crystals come out of the solution – and the bigger the candy crystal grows.

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