House of Science educator Lindsey Morgan. Photo/Andrew Warner
HOUSE OF SCIENCE
Growing crystals
This week's investigation not only demonstrates waters ability to dissolve solids but will also show evaporation and diffusion.
What you will need
* Washing soda crystals
* A saucepan
* A glass jar
* A spoon
* A pencil
* Hot water
* Food colouring
* A piece of string
* An adult!
What you need to do
1.
Put 1 cup of water into your saucepan. Ask your adult to put this on a stove to boil.
2. When the water is boiling, carefully stir in one tablespoon washing soda into your water until it is dissolved.
3. Add another spoon of washing soda and stir until it is dissolved. Keep adding soda, one tablespoon at a time until the soda will not dissolve and sinks to the bottom of the saucepan.
4. You now have your saturated solution. Ask your adult to pour it into a glass jar and add a couple of drops of food colouring. The food colouring will slowly diffuse into the hot water.
3. Tie a piece of string around your pencil, long enough for the loose end to be in the middle of the liquid in the glass.
4. Place the loose end of string into your glass/solution and lay the pencil across the top of your jar
5. Put your jar in a warm place. Check your crystal growth after two days. Then remove it from the remaining liquid and leave it to dry completely on a sunny window sill.
What is happening?
The water in your solution will evaporate. This means it turns into water vapour and small molecules leave the liquid to join the other water molecules in the air. It does this because the surface of the liquid meets the less saturated air.
