Eduard-Job-Foundation for Thermo- and Matterdynamics

Experiment 4.12: Ammonia Fountain

Experiment: Ammonia Fountain

Procedure:
An inverted round-bottomed flask filled with ammonia gas is connected by a glass tube to a reservoir of water (with phenolphtalein).

Observation:
Water rushes up into the flask with in-creasing speed, thereby forming a fountain and turns pink. 

Explanation:
Ammonia gas is remarkably soluble in water according to 

formel.gif

Because of the potential gradient the reaction takes place spontaneously.

Just a few drops of water are enough to decrease the pressure in the flask so drastically that water is drawn upward into it in a strong jet. 

Video (mpg4, 0:57)