Investigating the Differences in Inspired & Expired Air
- A simple experimental setup can be used to investigate the differences between inspired and expired air
The limewater test
- When we breathe in, the air is drawn through boiling tube A
- When we breathe out, the air is blown into boiling tube B
- Lime water is clear but becomes cloudy (or milky) when carbon dioxide is bubbled through it
- The lime water in boiling tube A will remain clear, but the limewater in boiling tube B will become cloudy
- This shows us that the percentage of carbon dioxide in exhaled air is higher than in inhaled air
