Today’s experiment is very simple, but hopefully fascinating for even very young children. We’re going to investigate which solids dissolve in water.
When a substance dissolves in water, you can’t see it anymore, it’s still there, but has mixed with the water to make a transparent liquid called a solution.
We call substances that dissolve in water soluble. Sugar and salt are examples of soluble substances.
Substances that do not dissolve in water are called insoluble. Sand and flour are examples of insoluble substances.
- Transparent containers – test tubes or beakers
- Water ( warm and cold )
- Substances to try to dissolve eg. sugar, coffee, pepper, sand, flour, salt.
Add a teaspoon of whichever solid you are testing to a glass of cold water and a glass of warm water, stir and observe the difference.
Watch to see if the solid dissolves in the warm water and cold water and if one is better than the other.
Can you design a chart to record your observations?
Which solids dissolve in water
Things like salt, sugar and coffee dissolve in water. They are soluble. They usually dissolve faster and better in warm or hot water.
Pepper and sand are insoluble, they will not dissolve even in hot water.
For older children
Everything is made of particles which are always moving. When a soluble solid ( solute ) is mixed with the right liquid (solvent), it forms a solution. This process is called dissolving.
Two things that affect the speed at which a solid dissolves are temperature and the size of the grains of the solid. Caster sugar which is made of fine particles will dissolve quickly, but bigger sugar particles will take longer.
Solids dissolve faster in hot water as in hot water the water molecules are moving faster, so bump into the solid more often which increases the rate of reaction.
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