Page 13 - Science 7 NEP Booklet

Activity 8 Scientific Experiential
Learning
Temper

Volume of Air Exhaled

• Fill a plastic bottle four-fifths with water. Close it with a rubber cork in
which two holes have been made.

• Add a few drops of food colouring to the water (avoid ink).

• Pass a short glass tube and a long glass tube through the two holes of the
rubber cork. Take care that the shorter tube does not reach the water and
the longer tube almost reaches the bottom of the bottle.

• Connect a rubber tubing to the long glass tube so that it touches the
bottom of a graduated cylinder.

• Connect a short piece of rubber tubing to the short glass tube for you to
blow into.
• Cover the opening of the shorter length of rubber tubing with a paper
napkin. Inhale normally and then exhale normally into the rubber tubing.

What do you observe? You will see that the water moves through the rubber
tubing into the graduated cylinder. Why? The volume of exhaled air causes
an equal volume of water to be pushed out into the graduated cylinder.

• Note the reading of the coloured water collected in the graduated
cylinder.
• Pour the coloured water from the cylinder into two litre plastic bottle.

• Exhale two more times and keep collecting the water from the graduated
cylinder into the bottle. Record the readings and then calculate the
average of three readings. The average volume is the volume of air that
you exhale.
• Repeat this experiment and calculate the average volume of exhaled air
after running for 15 minutes.

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