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”.
Arrange the baking soda in the bowl around the tea light using the tea spoon.
Light the tea light.
Slowly add vinegar to the baking soda around the tea light. Be careful not to put the vinegar directly into the flame.
Observe what happens to the candle.
When vinegar reacts with baking soda, the gas carbon dioxide is formed. Carbon dioxide is heavier than air and stays in the bowl. Carbon dioxide gas replaces the air with the oxygen needed for the tea light’s flame in the bowl. Finally, the non-flammable carbon dioxide gas smothers the flame.
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
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.
Titration experiments can be used to produce pure salts by reacting acids and alkalis in a very controlled way. A neutralization reaction takes place where acid and alkali react to form the neutral products salt and water.
In a titration, the acid is added to a fixed volume of alkali, for example sodium hydroxide, in a conical flask. A burette is used to slowly drip the acid into the conical flask. The burette is a tall apparatus with a tap at the bottom that controls the flow of the acid (see image above).
A few drops of indicator are added to the alkali, so you can follow the reaction. The end-point is when the indicator changes colour. A single indicator like phenolphthalein is used because it shows only one very obvious colour change and gives you a sharp end-point. Phenolphthalein will change from pink to colorless at the end-point.
To obtain the pure salt, the water needs to be evaporated from the solution after the end of the titration by heating.
In industry, titration is used in many fields not only to produce pure salts, but also to test the amount of acids or alkalis in materials. For example, titration is very common to determine the amount of acids and alkalis in foods like chocolate. The method is also applied by construction companies to investigate the quality of building materials.
What is produced by a titration experiment?
Which reaction takes place generally during a titration experiment?
Name the tall apparatus used to add the acid to the conical flask with the alkali.
Which indicator can be used to identify the end-point of a titration experiment.
Why is universal indicator not used to identify the end-point?
What are the colours of phenolphthalein in an acid and in an alkali?
What needs to be done after the titration to obtain the pure salt?
Name two uses of titration experiments in industry.
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
Washing up liquid
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!
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.
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?