Ammonia Fountain

Dry ammonia gas is collected in a sealed flask. When a small amount of water is injected, the ammonia rapidly dissolves, creating a partial vacuum that pulls water up into the flask. An indicator shows the resulting alkaline solution.

1. Generate ammonia gas by gently heating a mixture of ammonium chloride and calcium hydroxide in a test tube.
2. Pass the ammonia through a drying tube to remove moisture.
3. Collect the dry ammonia in a sealed, dry flask kept warm until use.
4. Set up the flask inverted in a water trough with a jet tube connected.
5. Add phenolphthalein indicator to the water in the trough.
6. Inject a small amount of water into the flask using a syringe.
7. Observe as the ammonia dissolves in the water, lowering pressure inside the flask.
8. Watch the water rush into the flask, creating a “fountain” effect and turning pink from the alkaline solution.

Ammonia Fountain - North Carolina School of Science and Mathematics:

The Ammonia Fountain - Super Cool Science - Explained - Jon Bergmann:

📄 Ammonia fountain - Dynamic Science: https://www.dynamicscience.com.au/tester/solutions1/chemistry/chemicaldemos/ammonia.html

• Use different indicators (e.g., universal indicator) to show color changes.

• Eye protection required.
• Perform the experiment in a fume cupboard due to toxic ammonia gas.
• Handle hot glassware and chemicals with care.
• Ensure the collection flask is completely dry before use, as moisture reduces effectiveness.
• Clamp apparatus securely to prevent tipping.
• Do not inhale ammonia gas; ensure good ventilation.

• Why does the water rush into the flask so quickly?
• How does the solubility of ammonia in water compare with other gases?
• What role does the indicator play in this experiment?
• What chemical species are present in the solution after ammonia dissolves?
• How would the demonstration change if the flask contained air instead of ammonia?