NOTE ON THE COMBUSTION OF METALS IN OXYGEN AND SULFUR SIDNEY J. FRENCH Colgate University, Hamilton, New York
IT IS often desirable to point out to beginning students similarities and differences in the behavior of two elements in the same family. This is a simple matter if both elements exist normally in the same state. In the case of oxygen and sulfur, however, the one being a gas and the other a solid, it is necessary to make the comparison in the gaseous state. This can be accomplished in the following simple manner. An oxygen-generating mixture consisting of potassium chlorate and manganese dioxide is placed in the bottom of one hard glass test-tube and a few grams of sulfur in another. A loose wad of steel wool is placed in each tube so that i t stands a short distance above the solid. The tubes are then heated, the heat being gradually extended upward to include the steel wool. Upon reaching the ignition point, the wool burns with a brilliant flash in oxygen, but is little affected by the
sulfur vapor. Copper wool or fine turnings may then be substituted for the steel wool. In this case, the copper is but superlicially oxidized in oxygen, but bums vigorously in sulfur vapor. Thus, the anomaly in the behavior of oxygen and sulfur toward these two metals is visually illustrated. Other metals may be used in a somewhat similar manner by being properly suspended in the tubes. Caution should be exercised in allowing very active elements to come in direct contact with the oxygengenerating mixture. This method of illustrating the properties and behavior of oxygen can be used in the laboratory in place of the longer method so commonly used; this consists of generating the gas in a prepared generator, collecting i t over water in bottles and inserting the preheated metals or other elements in the collected gas.
