Try this investigation to explore irreversible changes and changing different variables
This resource is also available in Welsh and Irish
Get the Welsh language version.
Get the Irish language version.
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.
Learning objectives
- To understand that chemical changes produce new materials and are irreversible.
Enquiry skills:
- 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.
Teacher notes
Classroom slides
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.
Equipment list
Per pair/group:
- Beakers/containers
- Spoons/mixing implements of appropriate size or pre-measured amounts in cake cases
- Pipettes (optional)/fine paintbrushes
- Citric acid
- Bicarbonate of soda
- Water
- Oil (rapeseed/baby oil) *allergies
- Food colouring/essential oil for colour and scent *allergies
- Salt
- Stopwatches
As citric acid is not found in all supermarkets it may be easier to source online or where home brewing materials are sold.
Additional resources
- 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.
Downloads
Bath bombs: teacher notes
Editable handout | Word, Size 0.27 mbBath bombs: teacher notes
Handout | PDF, Size 0.24 mbBath bombs: classroom slides
Presentation | PowerPoint, Size 10.76 mbBath bombs: classroom slides
Presentation | PDF, Size 4.09 mb
Additional information
Primary science investigations were developed in collaboration with the Primary Science Teaching Trust
Primary science investigations
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- 5Currently reading
Fizzy irreversible changes and bath bombs
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- 9
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