Consumer Chemistry Demonstrations Part of the teaching methodology in a consumer chemistry course for nonseienee students involves the use of demonstrations to illustrate principles and to augment discussions. During a presentation on the chemistry of cleaning agents, the potential hazards of mixing certain cleaning agents are discussed. In particular, the labels of many acidic cleaning agents, such as toilet bowl cleaners, admonish usen not to mix the product with chlorine-type bleaches or products. The usual demonstration for this discussion has heen to place a 5%sodium hypochlorite solution in a Florence flask and then add hydrochloric acid. The resulting chlorine gas is hard to see, especially in large lecture halls. In addition, the classrooms where the course usually must be taught are not equipped with a fume hood, and the chlorine invariably leaks into the room causing a stink. The demonstration has heen modified by using an indicator for the chlorine gas, which reduces the amount of chlorine that must be generated. The demonstration is performed by adding 10 g of a common toilet howl cleaner containing sodium bisulfate to a l-L Florence flask. A 1-cm filter paper is soaked in a 0.1 M potassium iodide solution and olaced in the neck of the Florence flask. Finallv. 5 mL of a commercial bleach (5%aaueous NaOCI) is added to the the flaskisa~~cklvstonneredli~htlv. it rises .~ .flask thr&h .~~ n lone-stem funnel. and then ~~~-~~ ~. , As the chlorkeeasiseener~ted. ,. .. in the flask and or~drreathe iudide ron toiudine, which colorstl~rwhite pnpm hrown. E w n from the rearclf the lecture hall students are ahle tu see this color change far more readily than the farm ydluw-peen of chlorine. The r
