MYP 7 Science - Chemistry

MYP 7.4.5: Carbon dioxide in the air

Carbon dioxide in the air, the carbon cycle, photosynthesis, respiration, combustion, fossil fuels.


  • To know the sources of carbon dioxide in the air are both natural and anthropogenic
  • To appreciate that the percentage of carbon dioxide in the air has been increasing since the industrial revolution.
  • To understand the mechanisms of the greenhouse effect and global warming
  • To understand the term "fossil fuels".
  • To know that limewater can be used to test for carbon dioxide.
  • Bicarbonate indicator to test carbon dioxide
  • To prepare a sample of carbon dioxide and test its properties (colour, smell, density, flammability)


Possible approach burning candles to show CO2

Exhaled air through limewater to show CO2

Student activity

Make carbon dioxide generators out of side-arm tubes, marble chips and hydrochloric acid and rubber tubing.

Pass the carbon dioxide through a solution of calcium hydroxide (limewater)

Collect some CO2 and test it with a lighted splint

Collect some CO2 and test it with damp universal indicator paper.

Teacher Demo

Collect a gas jar of carbon dioxide and pour it onto a lit candle in a beaker. This demonstrates that carbon dioxide is a dense gas.


Environmental Science: The Carbon and Oxygen Cycles p50-1

Technicians notes

Bicarbonate indicator:

Two solutions are prepared separately:

Solution A: 0.02 g of thymol blue, 0.01 g cresol red and 2 mL of ethanol

Solution B: 0.8 g of sodium bicarbonate, 7.48 g of potassium chloride and 90 mL of water

A working solution is prepared by mixing 9 mL of A + 1 mL of B in 1000 mL of distilled water.

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Copyright: 2003 Isis Publication