Lemon Volcano

You will need

  • 1 plate or tray
  • 1 lemon
  • 1 cutting knife (to cut the lemon)
  • 1 butter knife
  • Baking soda
  • 1 table spoon
  • Food colouring (1 to 4 colours of your choice)

What to do

  1. Cut your lemon in half. Then cut of a bit at the bottom, so that the lemon can now stand up.
  2. Place the lemon on the plate or tray with the wide side facing up.
  3. Use the butter knife to poke holes in the flesh.
  4. Add 8 to 10 drops of food colouring spread out over the lemon.
  5. Add 1 heaped table spoon of baking soda.
  6. 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.

You can 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:

Reacting Vinegar and Baking Soda

You will need:

  • Baking soda (= alkali)
  • Vinegar (= acid)
  • 1 empty, clean bottle
  • 1 spoon
  • 1 balloon

What to do:

  1. Fill the bottle about one third with vinegar (your acid).
  2. 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.
  3. Put the opening of the balloon over the opening of the bottle. (See image above.)
  4. Now tip the baking soda from the balloon into the bottle.
  5. 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

  1. Which signs do you see that tell you a chemical reaction is happening?
  2. What happens generally in a neutralization reaction?
  3. Which two products are formed in the neutralization reaction?
  4. Which colour would the following have when adding universal indicator?                   A) Vinegar          B) Baking soda       C) The products after the reaction

You can watch this experiment on YouTube:

Disappearing Egg Shell

Background

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:

  1. Place the raw egg carefully in the glass.
  2. Fill the glass with vinegar until the egg floats.
  3. Observe what happens on the egg shell. You should see effervescence.
  4. Leave your experiment for three days in a cool, safe place.
  5. After three days remove the egg from the vinegar and carefully dry it with kitchen roll paper.
  6. Take the egg in your hand and squeeze it gently. What does it feel like?

You can watch this experiment on YouTube:

Colourful Milk Experiment

You will need:

  • 1 plate
  • milk
  • food colouring (2 to 4 colours)
  • washing-up liquid
  • 1 cotton bud

What to do:

  1. Pour the milk on the plate.
  2. Choose 2 to 4 colours of food colouring that you want to use.
  3. Add 8 to 10 drops of each food colour to the milk in different spots. (See image above.) Do NOT stir or mix.
  4. Put one drop of washing-up liquid on the end of your cotton bud.
  5. Hold the end of the cotton bud into the middle of the milk with the food colouring.
  6. Observe what happens.
  7. You can move the cotton bud around the plate to different places and observe what happens.

How to build a hovercraft

You will need:

  • 1 balloon
  • 1 plastic pull-out bottle cap
  • All-purpose glue or hot-glue gun (if you don’t have this, tape will do)
  • 1 old CD

What to do:

  1. Glue the plastic pull-out bottle cap over the hole in the middle of the CD using all-purpose glue or tape. If you are using all-purpose glue, ask an adult to help you and let the glue dry off.
  2. Blow up a balloon.
  3. Make sure the pull-out cap is open.
  4. Attach the balloon to the pull-out cap by stretching its opening over the cap. (See image above.)
  5. Put the craft on a table with the CD facing down and the balloon up.
  6. The air escaping from the balloon will produce an air cushion underneath the CD. This reduces the friction between the table and the CD and your hovercraft will move over the table very fast.
  7. Your hovercraft will speed along until it runs out of air and you have to blow the balloon up again.

Investigating Pressure with a Plastic Bottle – Experiment

Introduction

Air is made from gas particles. They constantly move around at a high speed. When speeding around like this, the particles often collide with the walls of their containers. For example, the air particles in a balloon move around and hit the balloon’s walls. These collisions cause the balloon to stay inflated. We call this gas pressure.

There are two ways to affect gas pressure. One is to change the number of air particles. When you blow up a party balloon, you add more air particles to it. More gas particles hit the walls more often and the balloon’s pressure increases.

The second method to increase pressure is by raising the temperature. When it is warmer, the gas particles have more energy and move faster. If the particles move faster, they hit with the walls more often and the pressure increases. When decreasing the temperature by cooling, the gas pressure will decrease.

In this experiment we are going to look at what happens to the pressure inside a plastic bottle when you cool down the temperature.

What you will need

  • 1 empty plastic bottle (a small bottle is enough, 500 ml or even smaller)
  • Freezer

What to do

  1. Remove the lid and put the empty plastic bottle in the sun or on the radiator to heat up a bit.
  2. Close the lid tightly, so nor more air can move in or out of the bottle.
  3. Put the bottle in the freezer and wait for one hour.
  4. Collect the bottle from the freezer. What has happened to it? Take notes.
  5. Now observe the bottle for a couple of minutes after taking it out of the freezer.

Questions

1. What happened to the bottle in the freezer?

2. Why did this happen? Look back at the introduction to find some clues.

3. What happened to the bottle after you took it out from the freezer?

4. Why did this happen? Look back at the introduction to find some clues.

5. Why was it important to close the lid tightly before putting the bottle into the freezer?

6. How could you improve this experiment?

Testing Acids and Alkalis in the Kitchen

Background

In this experiment you will investigate the properties of three substances in the kitchen to determine if they are acids or alkalis.

Acids have a sour taste. In high concentrations acids can burn your skin and other living tissue. But the acids you are working with in the kitchen have very low concentrations and safe to touch. Examples of laboratory acids are hydrochloric acid, sulphuric acid and nitric acid.

Alkalis have a bitter taste and feel slippery when you touch them. Alkalis in high concentrations can burn your skin or other living tissue too. But the alkalis in your kitchen have low concentrations and are safe to touch. One common alkali in laboratories is sodium hydroxide.

You will need:

  • 1 lemon or lemon juice
  • vinegar
  • dish washing soap (liquid soap for hand washing works too)

What to do:

  1. Copy the table below.
Substance Look Feel Taste Acid or alkali?
Lemon juice
Vinegar
Dish washing soap

 

  1. If you have a lemon instead of lemon juice you need to squeeze it now and collect some juice from it for your experiment.
  2. Look at the lemon juice, vinegar and dish washing soap and record in your table what they look like.
  3. In turns drop a bit of each of the substances on your hand and test what they feel like. Record it in your table.
  4. Now taste the lemon juice and the vinegar. Record what they taste like in your table. You do not have to taste the dish washing soap.

Questions

  1. Based on your data decide which substances are acids and which are alkalis and record it in your table. Use the text in the introduction to help you. It gives you information about the properties of acids and alkalis.
  2. What do you expect the dish washing soap would taste like? Why?
  3. Name two properties of acids.
  4. Name three properties of alkalis.
  5. Name two laboratory acids.
  6. Name one laboratory alkali.
  7. Which other acids and alkalis do you know that you have in the kitchen or the home?

The Science of Chocolate – Investigating the States of Matter

You will need:

  • Some pieces of chocolate (dark chocolate works best, but you can use milk chocolate too)
  • Pan
  • Bowls
  • Water

What to do:

  1. Put water in the pan and place it on the hob.
  2. Break the chocolate into small pieces and place it in a bowl over the pan with the water. (See image above.) Be careful not to mix any water with the chocolate.
  3. Turn on the hob and gently heat the water with the chocolate and bowl on top.
  4. Once the chocolate has melted, turn off the hob.
  5. Place half of the molten chocolate in a freezer to cool. If you do not have a freezer, you can use the fridge.
  6. Let the rest of the chocolate cool slowly at room temperature.
  7. Once both chocolates have frozen, compare what they look like. In addition, test how they taste differently and how they feel to the touch.
  8. Although both chocolates freeze and become solid again, they will be very different depending which temperature they are freezing at.

Questions

  1. A) Draw a diagram showing the arrangement of the chocolate particles in a solid.  B) Draw a diagram showing the arrangement of the chocolate particles in a liquid.
  2. What happens to the energy of the chocolate particles when it melts?
  3. What happens to the energy of the chocolate particles when it freezes?
  4. How is the chocolate that was cooled in the freezer different from the chocolate cooled at room temperature? Compare how they look, taste and feel when you touch them.
  5. The process of melting and freezing chocolate is quite important in food industry and chocolate making. Based on your experiment which temperature do you think is better for freezing chocolate, room temperature or the freezer/fridge? Why?

How to make an atomic model with sweets

You will need:

  • String
  • Scissors
  • Coloured sweets, for example smarties or skittles

What to do:

  1. Choose three colours that you want to use in your atom. Once colour for the protons, one for the neutrons and one for the electrons.
  2. Cut some string to make the electron shell.
  3. Put the sweets that represent the protons and the neutrons in the middle. The middle of the atom is called the nucleus.
  4. Arrange the string in a circle around the nucleus. It will form the electron shell.
  5. Put the sweets that represent the electrons on the electron shell (string). Make sure that the amount of protons and electrons is the same.
  6. Your atomic model is now complete. If you wish you can label the atom and add the charges for protons, electrons and neutrons.

You can watch this experiment on YouTube: