Just a can of cola?

You have been asked by an independent laboratory to help them in their investigations to discover more about their rival’s soft drink

This experiment has no set time. 

Equipment

• Eye protection
• Can of cola
• Assorted tools for a range of experiments

Health, safety and technical notes

• Read our standard health and safety guidance here.
• Wear eye protection.
• Wear clothing protection if desired.
• This is an open-ended problem-solving activity, so the guidance given here is necessarily incomplete.
• In general, students should be reminded to consider the safety aspects of eating or drinking in the laboratory. 
• It is the responsibility of the teacher to carry out a suitable risk assessment, particularly for any tests for Al³⁺ ions which generally use ammonia or sodium hydroxide. 

Possible approaches

Very open-ended. A selection of the following could constitute a useful investigation.

Experiments

1. Volume of cola in can.
2. Density of cola in can.
3. Volume of gas released on opening underwater.
4. Tests on gas collected – combustion/limewater.
5. What is the can made of? Effect of magnet, acid, alkali on metal. Tests for AI³⁺. Density of the metal.
6. PH of the cola.
7. Measure of total acidity by titration (Decolorise with activated charcoal for some of the tests.)
8. Evaporate down – any solid residue?
9. Column chromatography to separate dyestuffs in the cola. Caramel?
10. Distil the cola – what is the distillate? Boiling point?
11. Is the cola optically active? What sugar is present? How much?
12. What is the can painted with – resistance to solvent attack? 

(Use your imagination for anything else. Caffeine, benzoic acid? – read the label.)

Possible extension 

Other colas, lemonade or other cans of carbonated soft drinks – what differences arise?

If students compare different soft drinks – panel discussion about why they prefer one to another.