Our eyes can only see a certain amount of pictures per second. They are actually quite slow. This is why we cannot see objects that are moving extremely fast. In this experiment we are going to use the slowness of our eyes.
You will need
Paper
Pencil
Pens or colouring pencils to draw a picture
Tape
Scissors
What to do
From the paper cut two pieces with the same shape and size.
Draw two different pictures on the two pieces of paper that can also go together, for example a rabbit on one piece of paper and grass on the other. You could also do a bowl of water on one piece and fish on the other one. Or a bird on one piece and a tree on the other one for the bird to sit on.
Tape both pieces of paper on either side at the end of a pencil. The pictures need to face outside.
Now rub the pencils between your hands as if it was a stick that you want to light a fire with.
Look at the pictures.
You will see both pictures combined together, for example the rabbit sitting on the grass or the fish in the bowl.
The reason this works is that our eyes are too slow to follow the fast movement of the pictures and can only see a limited amount of pictures per second.
Diffusion is the movement of particles from a place of high concentration to a place of low concentration. We can also say that particles move from where there are lots of particles to where there are less particles.
In this experiment we are going to look at the diffusion of colour particles. You will observe the colour moving away from the sweets where lots of colour particles are found to places with less colour particles in the middle of the plate.
You will need
M&Ms or Smarties
Plate
Water
What to do
Once you start this experiment, you cannot move it. So, make sure you choose a good spot to start.
Pour the bag of M&Ms or Smarties onto your plate.
Remove the sweets that landed in the middle of your plate.
Place the remaining sweets in a circle around the outside of your plate.
Remove any remaining M&Ms or Smarties that do not fit in the circle.
Slowly add water to your plate. It needs to reach the M&Ms, but they should not float. From now on you cannot move the experiment.
When a balloon is rubbed against hair, a towel or a jumper, it gains more electrons which have a negative charge. This gives the balloon an overall negative charge. Objects with a positive charge or no overall charge like a tin can will now be attracted (= be drawn) to the balloon. We call this “static electricity”.
You will need
Balloon
Towel, jumper or your hair
Empty soda can
Water tap
A smooth surface, e.g. a table
What to do
Blow up the balloon.
Put the empty soda can on its side on a smooth surface.
Rub the balloon on a towel, jumper or your hair to create static electricity.
Hold the balloon close to the side of the soda can, but do not let them touch.
Slowly move the balloon away from the soda can along the surface.
Observe what happens.
Rub the balloon again on a towel, jumper or your hair.
Open the water tap, so that only very little water is running. It should be almost dripping.
Hold the balloon close to the water, but do not let the balloon touch the water.
Density tells you how heavy a certain volume of a substance is. It decides which materials can float on water and which sink. For example, a rock will sink because its density is higher that the density of water. However, wood floats because its density is lower than that of water.
The same is true for liquids. Liquids with high densities sink, while liquids with lower densities float. We are going to use this to make a rainbow in a glass. Chocolate sauce has a highest density of the four liquids and will stay at the bottom. However, water has the lowest density and will, therefore, float on top.
You will need
1 Glass
1 Spoon
Chocolate sauce
Honey
Washing up liquid
Water
Red food colouring
What to do
Start by pouring chocolate sauce into your glass until it is one quarter full.
Use the spoon to carefully add the honey until your glass is half full. Do NOT stir!
Now add the washing up liquid slowly and until your glass is three quarters full.
In a separate glass mix water with red food colouring.
Carefully add the water dropwise until your glass is full. Do NOT stir!
Cut your lemon in half. Then cut of a bit at the bottom, so that the lemon can now stand up.
Place the lemon on the plate or tray with the wide side facing up.
Use the butter knife to poke holes in the flesh.
Add 8 to 10 drops of food colouring spread out over the lemon.
Add 1 heaped table spoon of baking soda.
Poke with the butter knife to mix the baking soda with the lemon juice.
The acid in the lemon reacts with the baking soda to form salt, water and carbon dioxide gas. The carbon dioxide gas will cause fizzing. We also call this effervescence.
Catalysts are substances that speed up chemical reactions. However, they do not directly take part in the reaction and are not used up themselves.
Cars contain catalysts in catalytic converters that split toxic substances released by the car’s engine into less harmful ones.
The gas bubbles inside coke are the result of a chemical reaction where carbonic acid decomposes to water and carbon dioxide gas. The bubbles you feel when drinking coke are carbon dioxide. The word equation for this reaction is:
Carbonic acid → Water + Carbon dioxide
Carbonic acid is the reactant. Water and carbon dioxide are the products.
Mentos can act as a catalyst and increase the speed of carbon dioxide production. This causes the foaming you can see when adding Mentos to coke. The scientific word for bubbles, fizzing or foaming is effervescence.
You will need:
1 bottle with coke or diet coke (Normal coke and diet coke both work, but diet coke is less sticky and easier to clean up afterwards.)
1 pack of Mentos
What to do:
Go outside to do this experiment.
Put the coke bottle on the floor and remove the lid.
Put about 5 pieces of Mentos inside at the same time.
Step back and watch.
You should see a lot of foaming due to the increased carbon dioxide production.
Questions
What is meant by a “catalyst”?
What is the catalyst in this reaction?
Is the Mentos used up in this reaction or not? Why?
What is meant by the “reactant” in a reaction? What is the reactant in this reaction?
What is meant by the “product” in a reaction? What are the products in this reaction?
Fill the bottle about one third with vinegar (your acid).
Use the spoon to fill the balloon with baking soda (your alkali). You might need another person to help you and hold the balloon open.
Put the opening of the balloon over the opening of the bottle. (See image above.)
Now tip the baking soda from the balloon into the bottle.
A neutralization reaction will take place where the acid and alkali react to form the products salt, water and carbon dioxide. All three products are neutral substances. Observe what happens.
Questions
Which signs do you see that tell you a chemical reaction is happening?
What happens generally in a neutralization reaction?
Which two products are formed in the neutralization reaction?
Which colour would the following have when adding universal indicator? A) Vinegar B) Baking soda C) The products after the reaction
In this experiment you will use vinegar to dissolve the shell of a raw egg. Vinegar is an acid and egg shells are made from calcium carbonate. Acids react with metal carbonates like calcium carbonate to form salt, water and carbon dioxide gas. The metal carbonate is dissolved in the process. You can find the word equation below.
Acid + Metal carbonate → Salt + Water + Carbon dioxide
You will be able to observe gas bubbles because carbon dioxide gas is formed. We also call this “effervescence”. The egg shell will dissolve leaving behind the raw egg in its membrane.
You will need:
Vinegar (= acid)
1 raw egg
1 glass
What to do:
Place the raw egg carefully in the glass.
Fill the glass with vinegar until the egg floats.
Observe what happens on the egg shell. You should see effervescence.
Leave your experiment for three days in a cool, safe place.
After three days remove the egg from the vinegar and carefully dry it with kitchen roll paper.
Take the egg in your hand and squeeze it gently. What does it feel like?
A tang of science 