In this investigation we will investigate the differences in composition between inspired and expired air. This is limited to O2, CO2 and water vapour but this investigation will observe temperature.
This investigation will remind you of the basic tests for CO2 and O2.
Equipment
- safety spectacles
- thermometer
- mirror
- boiling tube
- plastic straws
- paper towel
- limewater
- cobalt chloride paper
- wooden splint
- matches
Safety considerations
- WEAR safety spectacles
- be careful not to suck up the limewater into your mouth!!!!!
Method
For each of the steps below, you will need to record your observations. Read the method carefully.
a. Record the temperature of a thermometer. Blow gently onto the thermometer. record the temperature again.
b. Exhale gently onto the mirror. Test the vapour with cobalt chloride paper and record your results.
c. Pour limewater into the boiling tube to about a third of the way up. Pierce a papel towel with the straw and use the paper towel as a makeshift lid to the boiling tube. Blow gently through the straw into the limewater for 10 – 15 seconds and record the change.
d. Light a wooden splint and extinguish the flame but allow it to remain glowing . Exhale lightly onto the glowing splint and record your observations.
Recording data
1 For each of the tests, record your observations in the spaces below
a. Blow onto thermometer
………………………………………………………………………………………………………………………………….
b. Exhale onto mirror
………………………………………………………………………………………………………………………………….
c. Blow into limewater
………………………………………………………………………………………………………………………………….
d. Exhale on glowing splint
………………………………………………………………………………………………………………………………….
Analysis
a. Blow onto thermometer
………………………………………………………………………………………………………………………………….
b. Exhale onto mirror
………………………………………………………………………………………………………………………………….
c. Blow into limewater
………………………………………………………………………………………………………………………………….
d. Exhale on glowing splint
…………………………………………………………………………………………………………………………………
Source: Practical Workbook by Matthew Broderick
Investigation 12.2 Expired and inspired air, pages 104 and 105