W14 Water dissolves only a small amount of air
Living beings in small rivers suffer from breathlessness in stagant water. This is due to the fact that water contains only few water. More air is lost as soon as the temperature rises. This will be investigated in the following experiment.
What to do
Check how much air separates from water during heating.
Material
Tray, high ampoule (5 ml) with stopper, blunted hypodermic needle dropper bottle with cold water
Experiment
1. Fill a high ampoule  - as high as possible - whith cold water.
2. Pierce the stopper by a blunted hypodermic needle.
3. Press the stopper on the ampoule without leaving an air bubble inside.
4. Remove the needle (upper part of the photo).
5. Leave the ampoule at a warm place.
ALTERNATIVE: Do the experiment in a 5-ml syringe and keep it in boiling water.
Observation
Small gas bubbles at the walls of the ampoule (lower part of the photo).
Explanation
Water cannot dissolve much air. If water gets warm the solubility decreases.
Organisms in fresh water and in salt water may suffer from a lack of air if water gets warm.

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