Soda snake fireworks
Materials list, per student or group
- Heatproof mat
- 4 tsp of icing sugar
- 1 tsp of baking soda
- 5 tsp of isopropyl alcohol
- Matches, taper or gas lighter
This experiment can get very hot, so it is important that it is performed on a heatproof mat or heatproof surface. The reaction should be performed in a ventilated room. No smoke is produced, but the alcohol vapour has a tendency to smell.
Make sure that the sugar and baking soda fills the indentation evenly, otherwise your snake may appear with mutant legs and eyes! Making a narrow, deep indent in the sand with your little finger or a pencil will help to make your snake tall and slim.
The baking soda releases carbon dioxide when heated above 50 °C. Burning the alcohol creates the heat and caramelises the sugar, giving the snakes their black appearance. The snakes grow because of the pressure from the gas (CO2) being released. The reaction will cease when all the alcohol has burned.
Do not under any circumstances pour any more alcohol on the mound whilst the reaction is taking place, as isopropyl alcohol is highly flammable.
- What is fuelling the fire?
- How does the snake appear to grow from nothing?
- What gas is produced? How do you know?
- Is the process reversible or irreversible?
Transition to KS4
- What are the two products of the reaction?
- Can you think what the chemical equation would be?
- What links are there to the dehydration of sugar?
- Add food colouring to the sugar and baking soda - does it make a difference to the colour of your snake?
- Try the experiment on a bigger scale. What is the longest class snake you can grow?
Links to everyday life
Raising agents in cooking
When dissolved in water, baking powder - which is partly made of bicarbonate of soda – reacts with the water and releases carbon dioxide. The most common use for it is in home baking of foods such as bread and cakes. The gas produced helps to give a light, spongy texture. Look at a slice of bread to see the holes where the carbon dioxide bubbles were produced.
Carbon dioxide produces the bubbles in fizzy drinks. SodaStream allowed you to brew up fizzy drinks in your own home.
Antacids work by raising the pH, i.e. reducing the acidity, in the stomach. Many use bicarbonate of soda, which provides relief because of its alkaline properties.