MIXTURES
Pure Water from the Backyard or the Beach
- Safety Rules:
- Parent supervision
- Do this outdoors
- Materials you need are:
- a shovel
- crushed leaves of a succulent plant
- a large sheet of plastic wrap
- a pebble
- some heavier rocks
- a collecting container
This activity involves digging a hole in the ground or the sand. Check with a parent that they agree with this. Set up the materials as in the diagram. Make sure that the plastic wrap covers the hole well so that the evaporated water doesn't escape. Leave it for a few hours in bright sunlight. You have collected pure water in the collecting container.
If you have used enough moist leaves in the bottom of the hole, then the pure water will evaporate up to the plastic wrap. It will condense back to a liquid on the cooler plastic wrap and drip down into the collecting container.
Separate the Dyes in Food Colouring
- Materials you need are:
- paper towel
- food colouring or Smarties
- an eyedropper
- some water
Put the paper towel on a dry sink top. Drop two drops of food colouring or a Smartie in the middle of the paper towel. Then quickly drop two drops of water directly ont top of the food colouring.
The dye and water should start to spread immediately out in a circle from the centre. You should see coloured rings. Each of the dyes used (e.g. blue and green in blue food colouring) should separate into rings. The paper towel draws the different dyes further through the paper depending on their attraction to the paper. This is called Paper Chromatography.
How Much Sugar is in a Can of Softdrink
- Safety Rules:
- Parent supervision
- Take care with fire or heat
- Materials you need are:
- a can of regular softdrink (not the Diet type)
- a saucepan
- a stove
Pour the contents of a can of softdrink (not diet-free) into a saucepan. Place it on the stove and boil away the liquid. What remains is almost all sugar.
(Caution: The sticky substance that remains is extremely hot. Do not touch it. You must also clean the saucepan immediately when still warm, or you will have great difficulty cleaning it when cool.)
Fake Glass
- Safety Rules:
- Parent supervision
- Take care with fire or heat
- Materials you need are:
- a stove
- a baking sheet (from the supermarket)
- a flat tray
- butter
- white sugar
- a wooden spoon
- a saucepan
You are going to make the sort of fake glass that is used in the movies. When actors leap through window panes, they do not get hurt because it is not real glass but fake glass made of sugar.
Lightly butter a baking sheet, place it on a flat tray and put it in the refrigerator to chill. Pour a cup of white sugar into a small saucepan. Heat it over a low heat until it melts. Pour it onto the baking sheet on the tray and allow it to set in the refrigerator.
(remember to clean the saucepan straight away. It's best to fill the saucepan with water and boil it to clean it.)
Grow Crystals
- Safety Rules:
- Parent supervision
- Take care with fire or heat
- Take care with epsom salts and borax (They are poisonous)
- Wear gloves and goggles
- Materials you need are:
- a saucepan
- a spoon
- water
- various salts (e.g. common salt, epsom salts (also called magnesium sulphate), borax, sodium bicarbonate (also called baking soda) or even table sugar)
- a clear jar
- 2 pencils
- cotton thread
Half-fill a small saucepan with water. Boil the water on the stove and then add as much of one of the chemicals as will dissolve. Keep stirring all the time. Now add a little more until no more will dissolve. Set up the materials as in the diagram, and leave it for a few days. Look closely at the shapes of the crystals.
To make crystals, you must make a saturated solution (that is, a solution in which no more solute will dissolve).
More is Less
- Safety Rules:
- Parent supervision
- Take care with fire or heat
- Take care with methylated spirits (It is poisonous)
- Materials you need are:
- an accurate measuring cup
- a large container
- some methylated spirits
- some water
Pour exactly 200ml of water into the container. Now add exactly 200mL of methylated spirits to the water. Measure the combined amount. If you have measured accurately, you should have slightly less than 400mL of the mixture.