CIA Demonstration: The Ammonia Fountain (5.2.5)

Question 1

• Ammonia is less soluble in boiling water than in water at room temperature.

Answer 1

• Ammonia is less soluble in boiling water than in water at room temperature.

Question 2

• This property is used to create a partial vacuum in a flask, which allows water to be pushed up a tube, creating a fountain effect.

Answer 2

• This property is used to create a partial vacuum in a flask, which allows water to be pushed up a tube, creating a fountain effect.

Question 3

A flask containing aqueous ammonia is heated.
Ammonia is less soluble in boiling water than in
water at room temperature. This property causes
the flask to be filled with ammonia gas.

The flask is then inverted with a tube running into a
beaker of water at room temperature. Some of the
ammonia dissolves in the water, creating a partial
vacuum inside the flask. Since the pressure is
lower inside the flask than it is outside the flask,
water is drawn into the flask.

Phenolphthalein is a pH indicator that changes
from clear to pink in basic solution. When the
ammonia reacts with the water, ammonium ions and
hydroxide ions are produced. Hydroxide ions make
the solution basic, and the phenolphthalein turns
pink.

Answer 3

A flask containing aqueous ammonia is heated.
Ammonia is less soluble in boiling water than in
water at room temperature. This property causes
the flask to be filled with ammonia gas.

The flask is then inverted with a tube running into a
beaker of water at room temperature. Some of the
ammonia dissolves in the water, creating a partial
vacuum inside the flask. Since the pressure is
lower inside the flask than it is outside the flask,
water is drawn into the flask.

Phenolphthalein is a pH indicator that changes
from clear to pink in basic solution. When the
ammonia reacts with the water, ammonium ions and
hydroxide ions are produced. Hydroxide ions make
the solution basic, and the phenolphthalein turns
pink.

Question 4

What is Phenophthalen?

Answer 4

An acid-base indicator that remains colorless in acidic solutions but turns a pinkish color in basic solutions.