Cut a long strip from one sheet of kitchen roll. It should be 2 cm or 1 inch wide.
Choose one felt tip pen and draw a big dot at the bottom of your kitchen roll strip. IMPORTANT: Do not draw the dot all the way at the bottom, leave about 2 to 3 cm from the bottom to the dot.
Pour some water into a bowl or cup.
Place the bottom of your kitchen roll strip in the water and watch what happens. IMPORTANT: When you do this, the dot must be above the water.
Repeat the method with other felt tip pens.
The inks in felt tip pens are made by mixing different colouring materials, called “pigments”. We can use chromatography separate the different colours because some are soaked up the kitchen roll faster than others.
The reason is that the different pigments have different solubilities in water. The further the colour travels, the more soluble it is. Less soluble colours stay at the bottom.
If you don’t have marbles, use small rocks instead.
Vegetable oil, for example olive oil or sunflower oil
Syrup or honey
Cooking oil and syrup or honey can still be used or eaten after this experiment.
What to do
Fill each glass jar with a different liquid at least half full. Make sure that the liquids have the same height in each jar.
Drop a marble into each one and observe how fast the marble falls through the liquid inside.
The slower the marble falls, the higher is the viscosity of the liquid. Which liquid in this experiment has the highest and which the lowest viscosity?
It takes much longer to pour syrup into a glass than to pour water. This is because syrup has a high “viscosity”. This means that it does not flow easily. The higher the viscosity of a liquid, the slower it will flow.
You can test the viscosity of a liquid by dropping a marble into it. The slower the marble falls, the higher is the viscosity of the liquid.
Vinegar, lemon juice, water and bicarbonate of soda to test
What to do
Carefully chop the red cabbage leaves into small pieces on the chopping board.
Put the red cabbage in a sauce pan and add water until the red cabbage leaves are completely covered.
Gently boil the red cabbage for 10 to 15 minutes.
After the sauce pan has cooled down, collect the water in a large jar.
To better see the red cabbage water’s colour add some water to dilute it.
Transfer the red cabbage water into the 4 small jars.
Add a dash of vinegar to the first small jar with red cabbage juice and observe what happens.
Repeat step 7 for the other substances you want to test. Each substance goes into a new small jar with red cabbage juice.
What colour changes do you observe?
Red cabbage juice is a pH indicator. This means it changes colour depending on if it is in an acidic, alkaline or neutral environment. In this experiment you are testing some acids (vinegar and lemon juice), some alkalis (bicarbonate of soda) and a neutral substance (water).
Which colour changes can you observe in your experiment? What colour does red cabbage indicator have in acids, bases or with neutral substances?
Fill both jars with warm water. (From the tap is fine.)
Add washing soda to both jars and stir until no more washing soda dissolves.
Attach a paperclip to each end of the string or wool.
Place the ends of the string in the jars, so the string hangs between the jars.
Place a plate between the jars to catch the drips of the solution flowing along the string or wool.
Leave the jars for one to two weeks in a safe place and observe what happens.
The washing soda solution slowly soaks the string or wool and flows along it. As the solution drips off some washing soda is deposited slowly forming a crystal.
Water flowing underground dissolves minerals when it seeps through rocks. The minerals are deposited when the water drips of a cave roof. A crystal is formed that hangs off the cave rood which we call “stalactite”. When the water drips to the floor it deposits minerals there forming a crystal growing up from the ground which we call “stalagmite”.
In your experiment a stalactite grows hanging from the string or wool.
Heat proof surface, for example a pan or a ceramic plate
If you are allergic to nuts you can use sunflower and pumpkin seeds instead.
What to do
Cut a potato into a long cylinder or a tall rectangular cube.
Carefully cut a long thin strip from the peanut, almond and walnut.
Stick 1 peanut strip into the top of the potato. The potato will hold the peanut while it is burning.
Light the peanut strip with a match. Let it burn until it goes out.
Repeat steps 3 and 4 with one almond and one walnut strip.
Which nut burns longest? Which nut is easiest to light?
Nuts contain oil that can be lit to create a fire. The oil and the oxygen from the air undergo a chemical change during the fire turning them into carbon dioxide gas and steam. This type of reaction producing a fire is called “combustion”.
The nut that lights fastest and burns longest contains most oil. Which nut contained most oil?
Measure out 1 cup of cornflour and place it in a bowl.
Measure out ½ cup of water.
Slowly add some of the water to the cornflour and mix with your hands.
Then add some more water and keep mixing with your hands.
Continue adding water and mixing until your slime has the right consistency.
If gets is too runny you can add some more cornflour.
Add about 10 drops of food colouring until your slime and mix it.
You can store your slime in a plastic container with a lid. Your slime might still dry out a bit over time. If this happens you can just add some more water.
Mixing cornflour and water gives you a slime that behaves very peculiar. If you touch it very lightly it feels liquid like water. If you hit it very hard and fast it feels solid like a rubber ball. The slime reacts differently depending on the force that acts on it. The bigger the force, the harder the slime. The smaller the force, the more liquid the slime behaves. These kind of liquids are called “non-Newtonian”.
Shine the torch through the beaker of water. It looks white like the sun when it is high up in the sky.
Pour a little milk into the water in the beaker.
Stir the water gently, so that it all goes slightly white.
Shine the torch through the water again. It will look different.
Again, add a bit more milk to your glass and stir again.
Shine the torch through the water again and observe what the light looks like now.
You can repeat the steps of adding milk, stirring and shining a light through several times.
When the sun is low in the sky, in the morning and the evening, its light passes through more air than at other times of day. Tiny particles of air stop much of the sun’s light. Only orange and red light gets through. The same happens when you shine your light through the milk-water mixture. Tiny particles from the milk stop most of the light. Only some colours pass through. Which colours did you see?