Grow a Crystal

You will need

  • Short length of wool or string
  • Warm water
  • 2 Paperclips
  • 1 Plate
  • 1 Spoon
  • 2 Glass jars
  • Washing soda

What to do

  1. Fill both jars with warm water. (From the tap is fine.)
  2. Add washing soda to both jars and stir until no more washing soda dissolves.
  3. Attach a paperclip to each end of the string or wool.
  4. Place the ends of the string in the jars, so the string hangs between the jars.
  5. Place a plate between the jars to catch the drips of the solution flowing along the string or wool.
  6. Leave the jars for one to two weeks in a safe place and observe what happens.

Background

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.

You can watch a video of this experiment:

Combustion of Christmas Nuts

You will need

  • 1 Sharp knife
  • Matches
  • Heat proof surface, for example a pan or a ceramic plate
  • 1 Potato
  • 1 Peanut
  • 1 Almond
  • 1 Walnut
  • If you are allergic to nuts you can use sunflower and pumpkin seeds instead.

What to do

  1. Cut a potato into a long cylinder or a tall rectangular cube.
  2. Carefully cut a long thin strip from the peanut, almond and walnut.
  3. Stick 1 peanut strip into the top of the potato. The potato will hold the peanut while it is burning.
  4. Light the peanut strip with a match. Let it burn until it goes out.
  5. Repeat steps 3 and 4 with one almond and one walnut strip.
  6. Which nut burns longest? Which nut is easiest to light?

Background

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?

You can watch a video of the experiment here:

Home Experiment: Halloween Slime

You will need

  • Bowl
  • Measuring cup
  • Spoon
  • 1 cup of cornflour
  • ½ cup of water
  • Food colouring (you can choose which colour)
  • Plastic container with lid for storage

What to do

  1. Measure out 1 cup of cornflour and place it in a bowl.
  2. Measure out ½ cup of water.
  3. Slowly add some of the water to the cornflour and mix with your hands.
  4. Then add some more water and keep mixing with your hands.
  5. Continue adding water and mixing until your slime has the right consistency.
  6. If gets is too runny you can add some more cornflour.
  7. Add about 10 drops of food colouring until your slime and mix it.
  8. 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.

Background

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”.

You can watch the experiment as a video here:

Home Experiment: Make a Sunset

You will need

  • 1 Glass
  • Milk
  • Water
  • Torch
  • Spoon

What to do

  1. Shine the torch through the beaker of water. It looks white like the sun when it is high up in the sky.
  2. Pour a little milk into the water in the beaker.
  3. Stir the water gently, so that it all goes slightly white.
  4. Shine the torch through the water again. It will look different.
  5. Again, add a bit more milk to your glass and stir again.
  6. Shine the torch through the water again and observe what the light looks like now.
  7. You can repeat the steps of adding milk, stirring and shining a light through several times.

Background

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?

You can watch this experiment as a video here:

Air Pressure Experiments

You will need:

1st experiment:

  • Glass bottle
  • Balloon

2nd experiment:

  • One piece of card board
  • Glass
  • Water

What to do:

1st experiment:

  1. Stretch the opening of the balloon over the rim of the bottle’s mouth. Make sure that the body of the balloon is inside the bottle.
  2. Try to blow up the balloon.
  3. The air in the bottle has nowhere to go and pushes on the balloon. This increases the pressure in the bottle when you try to blow up the balloon and you will not be able to blow it up.

2nd experiment:

  1. Pour water into the glass until it reaches the rim of the glass.
  2. Place the piece of card board on the glass. Hold it down so the card board covers the rim all the way around.
  3. Still holding the card board, move above a sink.
  4. Turn the glass upside down while still holding the card board. Then let go of the card board.
  5. Air pressure forces the card upwards, against the glass. The pressure is strong enough to stop the weight of the water pushing the card away.

You can watch a video for this experiment here:

Home Experiment: Ghost in the Bottle

You will need

  • One glass bottle
  • One coin (2 Pounds or 2 Euros work well)
  • Freezer

What to do

  1. Place the open bottle in the freezer for 10 minutes.
  2. Remove the bottle from the freezer and moisten the rim of the mouth with some water.
  3. Cover the rim of the coin with some water, so that nor air can pass through.
  4. Place your hands around the bottle.
  5. Observe what happens.

Background

You will be able to observe the coin moving as if a ghost was in the bottle. The cold air in the bottle is warmed by your hands and expands. The coin and water prevent the air from escaping the bottle. However, if the pressure gets high enough, the coin acts like a valve and moves releasing the warm air from the bottle.

You can watch the video for this experiment on YouTube:

Home Experiment: Fire Extinguisher

You will need

  • Tea light
  • Tea spoon
  • Small bowl
  • Vinegar
  • Baking soda
  • Match to light the candle

What to do

  1. Place the tea light in the middle of the bowl.
  2. Arrange the baking soda in the bowl around the tea light using the tea spoon.
  3.  Light the tea light.
  4. Slowly add vinegar to the baking soda around the tea light. Be careful not to put the vinegar directly into the flame.
  5. Observe what happens to the candle.

Background

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.

You can watch this experiment as a video here:

Vinegar and Baking Soda Bomb

Background

Vinegar is an acid and reacts with baking soda to form salt, water and carbon dioxide gas. The extremely fast formation of carbon dioxide gas will cause your zipper back bomb to explode.

You will need

  • Plastic zipper bag
  • Vinegar (any kind will do, but you will need quite a lot of it)
  • Baking soda
  • Cup, glass or mug
  • Table spoon

What to do

  1. Go outside to do this experiment.
  2. Check your zipper bag to make sure that it does NOT have any holes or rips before the experiment.
  3. Fill your glass or mug completely with vinegar
  4. Pour the vinegar from your glass or mug into the plastic zipper bag.
  5. Place the zipper bag on the ground.
  6. Add one heaped table spoon of baking soda and quickly close the bag.
  7. Quickly step away from the zipper bag and watch what happens.

You can watch this experiment here:

M&M Diffusion Experiment

Background

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

  1. Once you start this experiment, you cannot move it. So, make sure you choose a good spot to start.
  2. Pour the bag of M&Ms or Smarties onto your plate.
  3. Remove the sweets that landed in the middle of your plate.
  4. Place the remaining sweets in a circle around the outside of your plate.
  5. Remove any remaining M&Ms or Smarties that do not fit in the circle.
  6. 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.
  7. Observe what happens to the colour of the sweets.

You can also watch this experiment on YouTube:

Coke and Mentos Fountain

Background

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:

  1. Go outside to do this experiment.
  2. Put the coke bottle on the floor and remove the lid.
  3. Put about 5 pieces of Mentos inside at the same time.
  4. Step back and watch.
  5. You should see a lot of foaming due to the increased carbon dioxide production.

Questions

  1. What is meant by a “catalyst”?
  2. What is the catalyst in this reaction?
  3. Is the Mentos used up in this reaction or not? Why?
  4. What is meant by the “reactant” in a reaction? What is the reactant in this reaction?
  5. What is meant by the “product” in a reaction? What are the products in this reaction?
  6. Where are catalysts used in our everyday lives?
  7. What is meant by “effervescence”?

You can watch this experiment on YouTube: