8Be(2)
Investigating inhaled and exhaled air
Name
Class
Date
What are the differences between inhaled and exhaled air?
8
B
e
Test 1: Which air contains more carbon dioxide?
Apparatus
• two double-holed
bungs
• two delivery tubes
• two boiling tubes
• limewater
• clean tubing for
mouthpiece
• eye protection
Wear eye protection.
Method
A Set up the apparatus as shown in the diagram.
mouthpiece
limewater
boiling tube A
boiling tube B
B Gently breathe in and out through the mouthpiece for 2 minutes.
C Notice what happens as you do this.
Recording your results
1 On the diagram, draw arrows to show the direction that air flows through the apparatus.
2 Mark on the diagram any changes you saw in the limewater.
Considering your results/conclusions
3 Which had the most carbon dioxide – inhaled or exhaled air?
4 Where did this extra carbon dioxide come from?
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Investigating inhaled and exhaled air (continued)
8Be(2)
Test 2: Is water vapour found in exhaled air?
Apparatus
•
•
•
•
•
Do not handle cobalt chloride paper
with fingers. If you touch the paper
accidentally, wash your hands
immediately.
mirror
forceps
beaker of water
pipette
dry cobalt chloride paper
8
B
e
Method
A Cobalt chloride paper is blue when it is dry. Put a
drop of water onto a piece of dry cobalt chloride
paper and notice what happens.
B Breathe out heavily onto a mirror several times.
C Use forceps to put a second piece of dry cobalt
chloride paper onto where you breathed.
Recording your results
1 What happened when you put water onto the blue cobalt chloride paper?
2 What did you see on the mirror when you breathed onto it?
3 What happened when you put blue cobalt chloride paper onto the mirror?
Considering your results/conclusions
4 What does the colour change of cobalt chloride paper on the mirror tell you about exhaled air?
5 Why has your breath got water vapour in it?
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8Be(2)
Investigating inhaled and exhaled air (continued)
Test 3: Investigating the temperature of inhaled and exhaled air
Apparatus
• thermometer
8
B
e
Method
A Measure the temperature of the air with
the thermometer.
B Breathe heavily onto the bulb of the
thermometer several times and record the
temperature of your breath.
Recording your results
1 Record the temperatures in this table.
Air temperature (°C)
Breath temperature (°C)
Considering your results/conclusions
2 a How is breath temperature different from the air temperature in the room?
b Explain this difference in temperature.
Summary conclusion
Write down three differences between inhaled and exhaled air.
I CAN...
• carry out a safe investigation • make accurate observations
• explain the differences between what is in inhaled air compared
with exhaled air.
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