Welsh 
Demonstrate the Greenhouse Effect
You will need:
- A desk lamp with a normal (not energy saving or fluorescent) bulb in
- Two jam jars with lids
- Some vinegar
- Some bicarbonate of soda
- Two thermometers, small enough to go into the jam jars
What to do:
- Pour a couple of cm depth of vinegar into each jam jar. Add a thermometer to each jar, close the jars and place underneath the lamp for 10 minutes or so.
- What temperature does the contents of the jars reach?
- Next, add a small (less than a teaspoon) amount of bicarbonate of soda to one of the jam jars and quickly close the jar again (add too much bicarb., and you will find it all gets quite messy).
- Place both jars under the lamp for another while. What temperature does each thermometer now measure?
- When vinegar and bicarbonate of soda are mixed, carbon dioxide is produced (you can demonstrate this by holding a burning match in the jam jar – it goes out, showing at least that there isn’t any oxygen left in the jam jar). Carbon Dioxide is a greenhouse gas so, as long as your desk lamp is emitting infra-red radiation, it will warm up more than the air in the top of the other jar.
More Information
This experiment:
For a more complete version of this experiment, go to http://www.rsc.org/education/chemistryteachers/Index.asp and
type 'greenhouse' in a 'free text' search (left hand menu).
The Greenhouse Effect/ Greenhouse Gases:
Many, many sites including http://www.ace.mmu.ac.uk/eae/english.html