Measuring the concentration of oxygen in the air
The pie chart shows the gas content in the Earth's atmosphere. Oxygen takes up 21%.
Some pupils want to investigate this and see for themselves if the air oxygen content around them is around 1/5 of the whole air volume.
The group of pupils planned their investigation as follows:
1. Moisten a piece of steel wool and place it at the bottom of a measuring cylinder.
2. Turn the cylinder upside down and immerse the open end in a beaker of water.
3. Let the oxygen be removed from the air sample. This may take several days.
4. Every day measure the air sample volume by reading the scale of the measuring cylinder.
Evaluate the pupils' method.