Why Does This Happen?
This is the classic 'invisible ink' experiment. Lemon juice is acidic and contains sugar.
The acid from the lemon juice affects the paper, effectively weakening the paper structure. Adding heat to the paper causes the acid affected paper to burn first. Additionally sugar will form caramel when heated, this is present in small quantities within the lemon juice.
- Try other fruit juices - which work best?
- Also try other weak acids; does this work as well?
- What will happen if you add extra sugar to your painting solution?
How to teach science, the way primary kids love
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