ACADEMIC TALK
Watch the lecture by Eleanor Hetherton below and don’t forget to take a look at the extra resources and have a go at the activity at the end.
Chemistry of fireworks
Eleanor Hetherton
Fireworks often seem like magic, lighting up the sky on special occasions. But there are actually very specific chemical processes behind their shapes and colours. Find out how different chemical reactions are used to make fireworks spectacular.
Further Reading
Click here to find out more detail about how different kinds of fireworks are made.
You can watch some firework demonstrations here.
This is a useful graphic about which chemicals make which colours.
If you’re interested in the environmental impact of fireworks, you can read about their pollutants here.
Choose one of the two activities below!
- Analysis: research and write a report on the different environmental impacts of fireworks, making sure to explain the science behind them. Include analysis of how these impacts might be reduced or mitigated.
- Experiment: visualise the colours in the metal salts in the stars of fireworks!
Materials:
- A candle
- Wooden splints or cotton swabs
- Small amounts of common, safe household chemicals:
- Table salt (sodium chloride) – yellow flame
- Baking soda (sodium bicarbonate) – yellow flame
- Epsom salts (magnesium sulphate) – white flame
- Borax (sodium borate) – green flame
- A small cup of water (for soaking the splints and for extinguishing)
- Metal tongs (if available)
- Safety goggles (if available)
- A safe, non-flammable surface to conduct the experiment
Procedure:
- Safety First: Ensure a safe, non-flammable workspace. If available, students should wear safety goggles. Make sure that the chemicals used are pure – check ingredients to ensure that you do not use chemicals that contain any other substances. Ensure there is adult supervision.
- Prepare the Splints: Soak the ends of the wooden splints or cotton swabs in water. This helps them to pick up the chemicals.
- Apply the Chemicals: Dip the damp end of the splint or cotton swab into one of the chemicals (e.g., table salt, baking soda, Epsom salts, or Borax).
- Light the Candle: Light the candle and hold it securely on a safe surface.
- Perform the Flame Test: Using metal tongs or holding the other end of the wooden splint, place the chemical-coated end of the splint in the candle flame. Observe the colour of the flame.
- Record Observations: Note the colour produced by each chemical. Compare the different colours and discuss why they might be different based on the chemicals used.
- Extinguish Safely: After observing the flame colour, extinguish the splint in the cup of water.
Answer these discussion Questions:
- What colours did you observe for each chemical?
- Why do you think different chemicals produce different colours when burned?
- How does this relate to the colours seen in fireworks?
Make a report about your experiment using your answers to these questions. Including either diagrams or photos of your process.
