Carbon Dioxide

The students are aware that carbon dioxide is a gas. However, their knowledge of the characteristics of carbon dioxide is limited. This demonstration illustrates the main characteristics of carbon dioxide and links the characteristics to an everyday application, i.e., CO2 fire extinguishers.

Video: Demonstration of the properties of carbon dioxide gas



  • Jam jar/beaker
  • Bicarbonate of soda
  • Vinegar
  • Tall jug
  • Bowl
  • Tea lights


Put some bicarbonate of soda into a tall jug. Slowly add the vinegar to allow the foam to form. Then pour the gas into the bowl of lit tea lights.


A tall jug works best for this experiment as the gas pours with greater effect.

Theory behind the hook

When bicarbonate of soda or baking soda is mixed with vinegar it results in three separate products: sodium acetate, water and carbon dioxide. Sodium acetate and water create the foam inside the jug while carbon dioxide is the gas that is formed. This gas is then poured out and extinguishes the tea lights. The chemical equation is as follows:
CH3COOH + NaHCO3 –> CH3COONa + H2O + CO2
Vinegar + Bicarbonate of Soda = Sodium acetate+ Water + Carbon dioxide
The first characteristic of carbon dioxide that is illustrated in this demonstration is that carbon dioxide is denser (heavier) than air. This is why carbon dioxide “stays” in the jug. The quenching of the tea lights shows us that carbon dioxide does not support combustion unlike oxygen.


Care must always be taken when working with naked flames
The waste products from this experiment can be disposed of down the sink.

How this hook works

As the demonstration requires common household materials, this demonstration could be conducted by the teacher at the start of the carbon dioxide topic or can be conducted by the student through the course of the chapter. Creating a link to real-life applications and prior knowledge, coupled with a visual representation of the concept should encourage deeper understanding of carbon dioxide and other gases.

Questions & Answers

  • If the gas produced quenches the tea lights, what does this tell us about the properties of carbon dioxide?
    That carbon dioxide does not support combustion
  • Compare and contrast the properties of oxygen and carbon dioxide?
    Oxygen support combustion while carbon dioxide does not.
  • How does the gas stay in the jug?
    Carbon dioxide is denser than air so therefore it stays in the jug

Cross Curricular Links

This can be linked to carbon dioxide in the atmosphere and global warming. As carbon dioxide is a gas this demonstration can be linked to the chapter on solids, liquids and gases.