The general ruls of solubility is that ”like dissolves like”. This means that polar solvents like water will dissolve more polar compounds such as ionic compounds like salts (e.g. sodium chloride). Less polar solvents such as organic solvents (e.g. propanone) will dissolve non-polar compounds such as plastics.
Nail polish contains non-polar compounds. Nail polish remover is made from propanone, a non-polar solvent which will dissolve nail polish, but not the polar ionic compound sodium chloride.
1. Collect two watch glasses. 2. Brush some nail polish into the middle of the two watch glasses and let it dry. 3. Collect one beaker with water and fill a second beaker with propanone or nail polish remover. 4. Drop ¼ spatula of salt into the beaker containing water and stir. Observe what happens. 5. Drop ¼ spatula of salt into the beaker containing propanone and stir. Observe what happens. 6. Drop water onto one watch glass with nail polish and watch what happens. 7. Then drop some propanone or nail polish remover onto the 2nd watch glass with nail polish and watch what happens.
Create your own results table.
1. Explain your results. 2. What are weaknesses of the experiment? 3. How could you improve the experiment?
Hold the large bird’s feather in front of one eye and watch the candle through the feather. Make sure you look through one of the white or gray coloured parts of the feather.
If you have positioned the feather correctly, the flame will appear to be multiplied in an X-shaped arrangement. You may have to shift the feather around a bit to find the best position to peak through and observe this.
The X-shaped pattern of the flame is produced when the light passes through the fine vanes and barbs of the feather. The light is bent and changes directions as it passes through them. This bending of light is called “refraction”. The flame appears many times because your eye is looking through several slits at the same time.
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.
Marbles (if you don’t have marbles, use small rocks)
Glass bowl or a large glass jar
What to do
Fill the glass bowl or jar with water.
Drop the marbles into the water. They quickly sink to the bottom. Roll the clay into a ball and drop it into the water as well.
The clay also sinks like the marbles.
Remove the marbles and the clay ball from the water.
Flatten the clay as much as possible, then shape it to make a boat and place it into the water. Now it floats!
Add one marble as a cargo. The boat settles lower, but still floats.
Add more marbles, one at a time. How many can you add before your boat sinks?
Large ships float on water, even though they are very heavy. However, a small object like a marble sinks. The mass of the object does not matter. Whether or not an object floats depends on its density and how much water it “displaces”, or pushes aside.
When the clay is shaped like a ball, it does not displace much water and it sinks. When shaped like a boat, the clay has a bigger area and displaces more water which makes it float. When adding your cargo of marbles, the boat settles lower to displace more water and carry the extra mass. When adding too many marbles, the boat will settle below the water line and sink.
This is important for ships. Too much cargo can lower them too close to the water line and make them vulnerable to sinking.
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?
Dinosaur toy figures or other animal to figures (plastic or wood, washed and dried)
1 White chocolate bar (cooking chocolate works best)
2 Table spoons
Heat proof bowl, e.g. glass or ceramic
Brush (not necessary, but helpful)
What to do:
Pour the brown sugar into the baking pan. Use the back of the spoon to pat it down.
Arrange your dinosaur or animal toys over the brown sugar. Gently press each toy down to make a dent in the brown sugar. Then remove the toys.
Break the white chocolate bar into small pieces and place them in the heat proof bowl.
Microwave the chocolate in the bowl for 30 seconds and then stir. Continue microwaving for 20 seconds at a time stirring after each time until the white chocolate is completely molten.
Slowly pour the molten white chocolate into the dents in the brown sugar. Then place in the fridge for 1 hour.
When the white chocolate has hardened, carefully dig each fossil out of the brown sugar with a spoon.
Carefully clean most of the brown sugar off using water and your fingers. If you have a brush you can use it to remove the sugar. Your fossils are edible.
Fossils are remains of organisms that lived a long time ago. This experiment is a model for fossil formation. The brown sugar represents soft soil or sediment where we can often find the imprints of creatures, for example foot prints.
The molten hot chocolate represents hot lava which fills empty spaces left by dead, buried organisms. The lava cools and finally forms rock fossils, showing us an image of the dead creature.