CR,O, AS A CATALYST IN KCLO, DECOMPOSITION MARTIN MEYER Brooklp Collage, Brooklyn, New York
OF ALL the substances which catalyze the thermal decomposition of KClOa, Crz0~seems, from the standpoint of low temperature and speed of reaction, to be the most efficient. As little as one per cent by weight will work satisfactorily and it is useless to employ more than five per cent. The catalytic cycle seems to involve KzCrzOn which functions equally well as a catalyst. Some chlorine is evolved, but as it is removed in collecting over water, this is no disadvantage. The familiar student experiment of prep&ation of
oxygen is better done by the following modifications of the usual directions: To five grams of Kc101 add one crystal of KzCr20rabout the size of the head of a large pin. Heat gently with the usual setup. The method has these advantages: it proceeds smoothly at a relatively low temperature and may be stopped at any time by cooling; when all oxygen is evolved the contents of the tube obviously solidify; more KCIOa may be added if desired without more catalyst; the test tube is easily washed out with hot water.
