Gas Solubility: The Fountain Effect 1
A small amount of water is injected into an inverted round-bottomed flask connected by a glass tube to a reservoir of water below it. Soon after the injection, the water from the reservoir rushes into the flask, turning red as it enters and forming a fountain inside the flask. Other color changes are also described [1,2].
MATERIALS FOR PROCEDURE A source of dry ammonia gas (cylinder with valve) 10 mL phenolphthalein indicator solution (To prepare 100 mL of solution, dissolve 0.05 g of phenolphthalein in 50 mL of 95% ethanol, and dilute the solution to 100 mL with distilled water.) 2-liter round-bottomed flask 2-holed rubber stopper to fit 2- liter flask 100-cm length glass tubing, with outside diameter of 8 mm 3-liter round-bottomed flask 2 ring stands 2 rings to support 2-liter flask cork ring to support 3-liter flask dropper 10-cm length rubber tubing to fit over dropper's open end 15-cm length copper wire, 16 gauge gloves, plastic or rubber 90-cm length plastic or rubber tubing solid rubber stopper to fit 2- liter flask pressure bulb
Preparation Assemble the glassware as illustrated in Figure 1. The glass tube should extend to within 10 cm of the bottom of the inverted upper, 2-liter flask and to within 1 cm of the bottom of the lower, 3-liter flask. When the dropper is inserted through the stopper, the constricted end of the dropper should be inside the 2-liter flask. Tighten the rubber tubing to the dropper with wire.
B.Z. Shakhashiri, Chemical Demonstrations: A Handbook for Teachers of Chemistry, Vol. 2, University of Wisconsin Press, Madison, WI (1985), pp. 205-210.
Unstopper and remove the 2- liter flask from the apparatus. Support it inverted on the second ring stand in a well- ventilated hood. Wearing gloves, attach the 90-cm length of plastic or rubber tubing to the valve of the cylinder of dry ammonia and insert the other end into the inverted flask. Fill the flask with ammonia gas by...