Discussion
After the experiment, ask the students to discuss among themselves in groups what happened. Encourage them to come up with their own ideas, using a worksheetw2 or the following questions:
Did the note burn?
If not, why not? (Water moistened the bank note, preventing it from burning. Alcohol is more volatile than water; the methylated spirit vapour burns just above the surface of the paper.)
What colour were the flames – and why? (The yellow flame indicates the presence of sodium from the salt.)
Then discuss the students’ ideas as a class, guiding them if needed to the correct explanations.