Making Sugar Crystals – Science at Home

Welcome back to another Science at Home post… this post was encouraged by Trisha from Inspiration Laboratory – she challenged me to get sciency in the kitchen! The obvious and most fun craft for kids in the science are Bicarbonate of Soda experiments as there is lots happening very quickly. We will be doing some in the future. In the meantime, I thought they would enjoy making some sugar crystals.

  • Materials: Sugar, water, saucepan, jars or glasses, coffee stirrers or wooden kebab sticks – food colouring optional
  • 3 cups of sugar to 1 cup of water
  • The food colouring was an experiment to see whether we could colour our crystals

1) Pour the sugar and water into a sauspan and stir. You will find that “not much happens” to the sugar. Water is able to absorb solids – but not very much. By heating it, you enable it to absorb more.

2) Start heating the pan and keep stirring – still not much happens, clearly the water isn’t hot enough. Bring to the boil and keep stirring – now the water is able to absorb all of the sugar.

3) Let cool a little and pour into your jar. Add a coffee stirrer attached to a piece of card (we just cut a slid) and let rest. Make sure the card does NOT cover the whole jar opening. As you want water to evaporate.

4) Leave for 2-3 weeks and let the Crystals form

Day 1

Day 3- 4

Day 7-8

We observed some crystals forming at the top an bottom of the jar immediately. The ones on the sticks started forming gradually after about 4 days. After a week, we had a good amount. After 2, the white could probably have been removed. But we are continuing to leave them a bit longer.

The Science?

This experiment is about “dissolving things” and “absorbing things”, as well as about structures and how some materials have a Crystal structure in their natural state. The water is able to absorb other materials (i.e. they dissolve in the water), but the ability to absorb is increased as you heat the water (this has to do with the molecules of the water moving around more, allowing for others to “slide in”). As the water cools, it’s ability to hold the molecules reduces and they are “pushed out” – the crystals start to form. Over time, the water evaporates from the jar – making the concentration of the sugar higher and again resulting in more crystals being formed.

Watch the rest of our Science in The Kitchen Experiments:

Visit Inspiration Laboratories discover what happens when you add water to cornstarch  flour or baking soda!

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