Creating a greenhouse gas
Carbon dioxide, made by burning fossil fuels such as petrol and charcoal is one of the more common of a number of gases which build up in our atmosphere and act like the glass of a greenhouse, reflecting back the rays of the sun so they go into the earth’s inner atmosphere, but do not go out so easily. In this way, just as a greenhouse keeps the plants inside it warm in winter, so the so called greenhouse-gases are making our planet warmer than it used to be and causing many environmental problems.
You will need:
- 2 transparent plastic bags
- rubber bands
- 5 teaspoons bicarbonate of soda (baking soda)
- half a cup white vinegar
- 2 spirit thermometers
- 2 polystyrene slabs (to be used as insulators)
And last but not least ... a helping hand from an adult.
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Method
First you must fill the first plastic bag with carbon dioxide. It is very important to take all atmospheric air out of the bag for the experiment to work – so use a flattened or collapsed plastic bag.
Carbon dioxide is produced by adding baking soda into an empty plastic bag and then pouring vinegar into it. This reaction produces carbon dioxide which fills the plastic bag.
When the bag is full of carbon dioxide insert the thermometer in the bag, trying not to let any gas out.
Next, take the second plastic bag and fill it with atmospheric air. Insert the second thermometer in this bag and tie it up.
Now place the bags, one containing the carbon dioxide and the other atmospheric air, on the insulating polystyrene slabs. This prevents heat coming in from the floor or the surface the bags are on and prevents the heat leaving. To heat them up faster, they can be put in the sun but with a shade covering the thermometer itself so it only reads the heat inside the plastic bag or balloon.
Wait about 10mins and compare the temperatures shown by each thermometer.
You should find that the thermometer inside the bag with the carbon dioxide shows a higher temperature than the one in the bag with the atmospheric air.
This is because carbon dioxide, which is produced by the burning of fossil fuels, traps heat in the atmosphere, which under normal conditions would escape to space.
Other options:
To model the greenhouse effect more realistically, one should have an internal plastic bag or balloon with air or water – same in both – containing the thermometer – and this should then be placed inside the other plastic bag with air or carbon dioxide around it.