Here is a nice experiment that was brought to my attention by Mark Headlee.
You will need 2 x 2litre plastic coke bottles. One should be about 1/3 full of coke the other should be identical but contain flat coke. Agitate the coke so that CO2 is given off then seal the bottle. This bottle contains a CO2 rich atmosphere. The bottle with flat coke will have a nitrogen/oxygen atmosphere. The bottles need to be sealed with a thermometer or temperature probe passing through the lid (I suppose you could also add a CO2 probe) but you need to be careful that the CO2 does not escape. If both bottles are left in identical conditions in the sun the one containing CO2 should heat up faster. Log temperatures for 10 to 20 minutes.
