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Simple and Safe Gas Science Experiments for Kids

A research enthusiast who is fascinated by science and forever on the lookout for educational experiments suitable for adults and kids.

Eruption of Mount Redoubt, Alaska

Eruption of Mount Redoubt, Alaska

Knowledge Is Power

Our world consists of different types of gases. In theory, it might prove overwhelming for kids to understand how gases work but you can make it easier for them by encouraging them to take up some gas-based science projects.

This page is a continuation of our previous Gas Experiments for Kids page.

How to Control Gas Thrust

Blow up a balloon and let it go without tying the neck. What do you see? You will see that because of the high pressure coming out of the neck of the balloon, it is forced to move around on its own. This kind of force that is responsible for pushing the balloon about is called thrust. Rockets like space rockets and firework rockets use thrust to move around.

The following Science experiment demonstrates how you can control this thrust.

Things you will need:

  1. A balloon
  2. A medium-sized button


  1. Blow up a balloon and hold it at the neck. There is no need to knot up the neck.
  2. Place the button into the neck opening of the balloon in such a way that the neck is stretched out to the sides.
  3. Ensure that the neck of the balloon is not directly opposite to your eyes. After this, let go of the balloon.
  4. You will notice that it will zoom off in a fairly direct line. The balloon will take up quite some time to empty as opposed to when there’s not a button. This is because the button disallows the air inside the balloon to escape too quickly.
Two aircrafts tied to a tree

Two aircrafts tied to a tree

How thrust works

A Science Experiment on How Gases Expand and Contract

In gases, there are tiny particles called atoms that are always on the move. A group of atoms collectively is called a molecule. These molecules move faster when the gas is heated up. The gas takes up more space when these molecules scatter i.e. it expands and becomes less dense. The gas contracts when it cools down and hence takes up lesser space.

The following gas Science experiment shows how gases contract.

Things you will need:

  1. A balloon (a sausage-shaped one)
  2. A cotton thread
  3. A refrigerator or freezer


  1. Blow a balloon up. Tie the end with a string.
  2. Now tie the cotton thread around the balloon. Make sure you tie it in such a way that the thread doesn’t move loosely around the balloon – it should be just tight.
  3. Put this balloon into a fridge or freezer and keep it there for a night or so.

When you take out this balloon, you would notice how loose the thread has become. The air in the balloon has contracted in the cold.

The balloon returns to the original shape after it warms up I.e. it will expand again to its original shape.

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3D and 2D representations of a particular molecule

3D and 2D representations of a particular molecule

Gases expanding and contracting - video

How to Squeeze or Compress Gas

Did you know that gases can be squeezed or compressed? Is it easier to compress air or water? Find out from the following simple Science experiment.

Things you will need:

  1. Water
  2. A plastic bottle with a top


  1. Fill up the bottle with water and close it with its lid.
  2. Squeeze the bottle from its sides. You will notice that you cannot squeeze in very far.
  3. Now empty out the water and try once again with an empty bottle. This time you will see that you are able to squeeze in farther.
Particles exerted by collisions inside a closed container

Particles exerted by collisions inside a closed container

Making bubbles in water

Making bubbles in water

Testing the Science of Making Bubbles

The following gas Science experiment tells you how you can create bubbles of gas in a liquid all by yourself.

Things you will need:

  1. A teaspoon
  2. Some baking powder
  3. A glass
  4. Water


  1. Take half a teaspoon of baking powder.
  2. Put this into a glass of water.
  3. Stir the mixture till the baking powder dissolves.
  4. You will see gas bubbles appearing on the surface. Baking powder mixed with water produces carbon dioxide.
  5. Did you know that there is air dissolved in water? To showcase this, fill up a glass with water and leave it to rest for several hours. You will see air bubbles forming in the inside of the glass.

Collecting gas over water

How to Collect Gas

Is it possible to put gases into containers? Yes. But it is not quite as easy as collecting fresh air. You can collect fresh air by taking an empty jar and waving it outdoors till all the air inside the jar gets out and the outside fresh air gets in. It takes hardly any time to do this. But how do you collect gases? One technique research labs use to collect gas is by collecting it over water.

The following Science experiment shows you how you can collect your breath over water.

Things you will need:

  1. Water
  2. A bendy drinking straw
  3. A plastic bowl
  4. A jar with a tight-fitting lid


  1. First, place the jar into a bowl or basin.
  2. Start pouring water into the bowl or basin till it's completely filled with water and it covers the jar fully.
  3. Now turn the jar in the bowl upside down. Since it is completely immersed in water, when you turn it upside down it will still contain water.
  4. Hold the jar firmly in place with one hand.
  5. Take the bendy drinking straw and put one end of it under the jar.
  6. Place the other end of the straw inside your mouth.
  7. Blow gently into the jar using the straw.
  8. Your breath will slowly replace the water inside the jar.
  9. Keep blowing and soon the jar will be filled with just your breath.
  10. The next step needs a lot of care. Still keeping the jar underwater, slowly cover the mouth of the jar with the lid and tighten it.

You now have a jar containing more carbon dioxide than normal air.

How Gases Can Be Used to Cut Metals

The flame from an oxy-acetylene torch has the power to cut metals as well as join them. Another tool named thermic or thermal lance also has the ability to cut metals. The tool uses iron rods to create heat that is super strong. The iron rods can get so hot that the tool can be used to even cut through concrete.

The following Science experiment demonstrates how a tool such as thermic lance is able to cut through substances easily. This requires parental help.

Things you will need:

  1. 2 candles
  2. An old knife with a plastic or wooden handle


  1. With the help of an adult, light a candle.
  2. Bring the knife’s blade close to the flame and hold it there for several minutes. Make sure not to touch the blade.
  3. Rest the other candle on its side.
  4. Try cutting this candle with the heated knife. If it has been heated up properly, the blade will effortlessly cut through the candle without any pressure required from your hands.
Thermal lance cutting a railroad bridge

Thermal lance cutting a railroad bridge

Thermic lance at work video

How to Test Air Humidity

What is humidity in the air? It is the amount of water vapor present in the air. Water vapor can be contained in abundance in the case of hot air. Whereas, cold air cannot contain much water vapor. The next time you go out on a really cold day, take notice of your breath. You will be able to see the water vapor in your breath condense into a cloud of tiny water droplets.

The following Science experiment will demonstrate this happening on a hot day.

Things you will need:

  1. A glass tumbler
  2. A refrigerator


  1. Take the tumbler and place it in the refrigerator.
  2. Keep it there for a night or so.
  3. When you take it out the next morning, blow into the glass tumbler a couple of times.
  4. You will see mist covering the inside of the glass.
  5. The glass jar’s coldness has led the water vapor in your breath to turn into liquid water.
Tropical forests have high humidity

Tropical forests have high humidity

Relative and Absolute Humidity Explained

© 2014 Kalpana Iyer


Kalpana Iyer (author) from India on June 07, 2014:

You are such a sweetheart. Thank you for the support :)

Chitrangada Sharan from New Delhi, India on June 07, 2014:

Your science experiments hub can be very useful for kids, who have to make certain Science projects at school. Therefore pinning it!

Very useful and interesting!

Kalpana Iyer (author) from India on June 06, 2014:

Thank you so much Nell! :) Glad you enjoyed the Science experiments page

Nell Rose from England on June 06, 2014:

Hiya, what fun! I love science, I did it at school and it totally captured me. Many people think science in any shape and form is boring, but not me! loved it! voted up and shared, nell

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