Gases in the Atmosphere

Question 1

Composition of air (%)

Answer 1

• Nitrogen (78%)
• Oxygen (21%)
• Argon (0.93%)
• Carbon dioxide (0.04%)
• Water vapour

Question 2

% of oxygen in air (copper)

Answer 2

The copper is in excess and uses up the oxygen to form copper oxide (CuO)

copper + oxygen -> copper oxide
2Cu + O2 -> 2CuO

Air is pushed back and forth across hot copper between two 100cm^3 gas syringes

Copper turns black, and eventually the volume of air stops decreasing

The volume of remaining air is measured

Question 3

% of oxygen in air (iron)