Chapter: 4.4

Gas Flow

Liquids (e.g. water) flow and can be transferred from one container to another. The same applies to gases. How could we observe gas flow?


The property of fluids is that they flow. Fluids are liquids and gases. Examples of fluids are water, oil, glycerin, alcohol and air. Air is a mixture of various gases – nitrogen, oxygen and other gases. Carbon dioxide (CO2) is also a gas. It is produced during combustion and breathing.

Example 1

Watch the video carefully.

What do you see?

In this experiment, a chemical reaction takes place between baking soda and vinegar. This produces gas – carbon dioxide.

Baking soda is a white powdery substance with no characteristic smell, which is often used in household purposes (for example, baking).

Oxygen is needed for combustion. When you pour carbon dioxide on a burning candle, you prevent it from getting oxygen. This is why the candle goes out.

Experiment 1

You can also do this experiment test yourself.

Materials: beakers, spoon, cork, baking soda, vinegar, candle, matches


  1. Put the candle in the first beaker and light it.
  2. Put a tablespoon of baking soda in the second beaker.
  3. Add two corks of vinegar to the baking soda.
  4. Wait for about 15 seconds.
  5. Pour the resulting gas on the burning candle.

Did your candle go out too? Explain why in your own words.