“Ammonia fountain” experiment
How to make a chemical fountain at home
In this amazing experiment, you’ll see how the solubility of ammonia and the power of atmospheric pressure can be used to make a miniature chemical fountain.
Wear a protective mask, gloves and glasses. The experiment must be carried out in a well-ventilated room. When conducting experiments with a large amount of ammonia, use a round-bottomed flask.
Warning! Only under adults supervision.
A similar experiment is included in the MEL Chemistry subscription
Reagents and equipment:
- sodium hydroxide (10 g);
- 25% ammonia solution (20 ml);
- conic flask;
- round-bottomed flask;
- cork with glass pipe;
- 1% solution of thymolphthalein;
Sprinkle sodium hydroxide into the conic flask and add the ammonia solution. Collect the ammonia that forms in the round-bottomed flask, turning it upside down. Seal with the cork with the glass pipe. Keep the flask upside down. In the crystallizer with water, add drops of the thymolphthalein solution and stir. Immerse the end of the glass pipe in the crystallizer so a little water gets into it.
Close the hole with your finger and turn the flask the right way up. The liquid that remains in the pipe must get into the flask. You can do this either by shaking it vigorously (but you may accidentally break the flask), or by opening the hole a little. As soon as the drop gets inside the flask, sink the pipe into the water and observe the liquid turn blue and rise up the pipe.
In the reaction of sodium hydroxide with the ammonia solution, ammonia gas is released. It is lighter than air, so the flask must be held upside down to make it fill the flask. It is important that the flask is completely dry, as ammonia has high solubility in water. The ammonia dissolves in the drop of water that we left there, so the liquid is quickly sucked inside. The pressure inside the flask drops and the liquid is forced upwards from the force of atmosphere pressure.