Fountain Experiment Logic
Why ammonia drives the fountain experiment.
Setting up the bench…
What this lesson covers
Why it matters
A dry flask of ammonia, one squirt of water, and suddenly a fountain erupts up into the glass. Extreme solubility makes it happen.
Predict first
Why does the fountain shoot up into the ammonia flask?
Ammonia is extremely soluble (~700 volumes in 1 volume of water). When a little water enters the gas-filled flask, the gas dissolves almost instantly, the pressure crashes, and outside air pressure forces water up as a fountain.
- Ammonia dissolves so fast that the pressure inside drops sharply — correct
- The ammonia gas pushes the water up
- The water boils and rises
What you do
Order the steps of the ammonia fountain experiment.
Check yourself
The fountain experiment shows that ammonia is…
Its huge solubility causes the sudden pressure drop that drives the fountain.
The water is pushed up the tube by…
As the inside pressure drops, atmospheric pressure outside forces water up.
- extremely soluble in water — correct
- almost insoluble in water
- denser than water
- the higher air pressure outside the flask — correct
- ammonia gas lifting it from below
- heat released as it dissolves