Try this investigation to explore irreversible changes and changing different variables
This resource is also available in Welsh and Irish
This experiment focuses on how materials change when they react together. First watch the ‘bath bombs’ demonstration video, then find out how your learners can use similar ingredients to explore an irreversible reaction.
- To understand that chemical changes produce new materials and are irreversible.
- To take measurements.
- To record data and results using scientific diagrams and labels.
- To use test results to make predictions.
Watch the video
The video below shows how to carry out the ‘bath bombs’ demonstration.
Download the supporting materials
Set up and run the investigation with your class using the teacher notes and classroom slides, featuring a full equipment list, method, key words and definitions, questions for learners, FAQs and more.
What do learners need to know first?
Learners should already be familiar with:
- States of matter (materials as solids liquids and gases).
- Melting and freezing as reversible changes.
- Dissolving as a reversible change.
- Powders, which are solids in granular form.
- Spoons/mixing implements of appropriate size or pre-measured amounts in cake cases
- Pipettes (optional)/fine paintbrushes
- Citric acid
- Bicarbonate of soda
- Oil (rapeseed/baby oil) *allergies
- Food colouring/essential oil for colour and scent *allergies
As citric acid is not found in all supermarkets it may be easier to source online or where home brewing materials are sold.
- Investigate irreversible changes further in our fire extinguisher investigation, lava lamp investigation or our freaky hand investigation.
- Explore another fizzy irreversible reaction in the sherbet and popping candy edible experiment.
- Read up on irreversible changes in this That’s Chemistry! textbook chapter.
Primary science investigations were developed in collaboration with the Primary Science Teaching Trust
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Fizzy irreversible changes and bath bombs