1. Respiration

2. Inhaled and exhaled air
Gas
% in inhaled air
% in exhaled air
Oxygen 20 16
Carbon dioxide
0.04
4.00
Nitrogen 79
Other 1

3. Inhaled / exhaled air Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
Limewater can be used to test for carbon dioxide.
Carbon dioxide turns limewater cloudy white.
This is because of the formation of an insoluble calcium carbonate
Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)

4. Hydrogen Carbonate Indicator
A bicarbonate indicator (hydrogencarbonate indicator) is a type of pH indicator that is sensitive enough to show a colour change as the concentration of carbon dioxide gas in an aqueous solution increases. Carbon dioxide produces a weak acid in solution.
High Medium Low

5. Hydrogen Carbonate Indicator
Draw and predict the colour of the hydrogen carbonate indicator in each tube
High CO Medium CO Low CO2

6. Anaerobic respiration

7. Anaerobic respiration

8. Anaerobic respiration