Kategori: Experiments/practicals for science lessons

Static Electricity at Home

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Background

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

  1. Blow up the balloon.
  2. Put the empty soda can on its side on a smooth surface.
  3. Rub the balloon on a towel, jumper or your hair to create static electricity.
  4. Hold the balloon close to the side of the soda can, but do not let them touch.
  5. Slowly move the balloon away from the soda can along the surface.
  6. Observe what happens.
  7. Rub the balloon again on a towel, jumper or your hair.
  8. Open the water tap, so that only very little water is running. It should be almost dripping.
  9. Hold the balloon close to the water, but do not let the balloon touch the water.
  10. Observe what happens.

You can also watch this experiment here:

Rainbow in a Glass

Publicerat i Chemistry Education, Experiments at Home, Experiments/practicals for science lessons, PhysicsLämna en kommentar

Background

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

  1. Start by pouring chocolate sauce into your glass until it is one quarter full.
  2. Use the spoon to carefully add the honey until your glass is half full. Do NOT stir!
  3. Now add the washing up liquid slowly and until your glass is three quarters full.
  4. In a separate glass mix water with red food colouring.
  5. Carefully add the water dropwise until your glass is full. Do NOT stir!

You can watch this experiment as a YouTube video:

 

Disappearing Egg Shell

Publicerat i Chemistry, Chemistry Education, Chemistry in the Home, Experiments at Home, Experiments/practicals for science lessonsLämna en kommentar

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:

Investigating Pressure with a Plastic Bottle – Experiment

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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

Publicerat i Chemistry, Chemistry Education, Experiments at Home, Experiments/practicals for science lessonsLämna en kommentar

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

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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

Publicerat i Chemistry, Chemistry Education, Experiments at Home, Experiments/practicals for science lessons, Physics1 kommentar

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:

How to make your own terrarium

Publicerat i Biology, Experiments at Home, Experiments/practicals for science lessonsLämna en kommentar

This activity is easy to do at home with children of any age.

You will need

  • Soil
  • Moss
  • Water (ideally from a stream or pond outside, but tap water will do also)
  • Glass jar
  • Stones (just a few)

What to do

  1. Collect what you need during a walk.
  2. Fill the glass jar first with the soil.
  3. Then add the stones.
  4. Next add the moss.
  5. Finally add some water. The moss likes it humid, but be careful not to drown it.
  6. Close the jar with the lid.
  7. Observe your biosphere carefully over the next days and weeks.

Which liquid dissolves candy canes fastest?

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  1. Get four beakers. Fill one beaker with cold water, one with hot water, one with oil and one with vinegar. The hot water can be taken from the kettle.
  2. You need to put one candy cane in each beaker at the same time and start your timer.
  3. Record your observations.
  4. Record the time when the first candy cane has dissolved. BUT, do not stop the timer.
  5. Record the time when the 2nd and 3rd candy cane have dissolved too.
  6. Write your conclusion and state which liquid dissolves the candy cane fastest and which is the slowest.

Orange peel flamethrower

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Here you can see the orange peel flamethrower in action.

The instructions are the following:

All you need is a candle and some orange peel. First, you have to light the candle. Then fold your orange peel, the shiny, orange side should face the candle. As you squeeze the peel, oils from the peel will squirt into the flame. The oils ignite and produce beautiful sparks in the candle flame. In addition, this experiment smells very nice and Christmassy.

So, go a head and surprise your family and friends with some amazing chemistry at Christmas dinner.