A Method for Producing Electrolytic Gas ABlASA F . WILLISTON, B. M. C. Du&e
IN DEMONSTRATING the very explosive character of electrolytic or detonating gas, the mixture of hydrogen and oxygen produced by electrolysis of a water solution of sulfuric acid, the gas is often collected in a very thin glass flask and exploded by an electric spark. This requires considerable care, some protection against flying glass, and is bothersome. Another method of collection is to pass the gas into a soap solution and ignite the bubbles of gas with a match. There is often trouble in this case because traces of acid destroy the soap bubbles, unless the gas is carefully washed with water and sodium hydroxide solution. A very simple method of avoiding trouble and complicated apparatus is the following: use a 3-neck Woulfe's bottle of suitable size, 200 to 500 ml. In the two outside openings put the two electrodes from a source of direct current, making sure that the stopper carrying each electrode fits gas-tight. In the center opening place a stopper carrying a short right-angle
High School, Fall River, Mussachusetts
bend. To the glass tube attach a piece of rubber tubing just long enough to reach the bench on which the bottle rests. In a 3-inch mortar to a depth of about 1 cm., place a soap solution. Fill the bottle with a solution of sodium hydroxide to within about 1cm. of the center neck, so as to reduce the volume of air above the solution to a minimum. Place the tube tightly in the center opening and turn on the current. Allow enough time for the gas produced to displace the air in the tube and bottle, then rest the end of the rubber tube on the bottom of the mortar beneath the soap solution. In a short time, about 1 to 2 min. with the current delivered from a 5volt rectifier, the mortar will be two-thirds filled with small bubbles of electrolytic gas. Shut off the current, set the generator aside, and remove the center stopper as an additional safety measure. The bubbles may be easily ignited with a match held in a pair of crucible tongs.
