Ammonia fountain

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The ammonia fountain is a type of chemical demonstration. The experiment consists of introducing water through an inlet to a container filled with ammonia gas.[1] Ammonia dissolves into the water and the pressure in the container drops. As a result, more water is forced into the container from another inlet creating a fountain effect. The demonstration introduces concepts like solubility and the gas laws at entry level.

An ammonia fountain demonstration

A different gas of comparable solubility in water, such as hydrogen chloride, can be used instead of ammonia.[2]

If the ammonia is replaced by a liquid vapor, such as water vapor, at a pressure higher than its room-temperature vapor pressure, a similar effect is produced. In this case, the reduction in pressure in the container is due to condensation of the vapor as the container cools to room temperature.


  1. ^ The Ammonia Smoke Fountain: An Interesting Thermodynamic Adventure M. Dale Alexander , Daniel T. Haworth J. Chem. Educ., 1999, 76 (2), p 210 doi: 10.1021/ed076p210
  2. ^ L.A. Ford, Chemical Magic, 2nd ed., Dover, 1993.

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