Microwave Mapping Demonstration Using the Thermochromic Cobalt Chloride Equilibrium

An update to the thermochromic cobalt(II) chloride equilibrium demonstration is described. Filter paper that has been saturated with aqueous cobalt(11) chloride is heated for seconds in a microwave oven, producing a color change. The resulting pink and blue map is used to colorfully demonstrate Le Chatelier's principle and to illuminate the hot spots in the microwave oven. The demonstration is a quick, easy, and colorful way to introduce Le Chatelier's principle to students in high school or general chemistry courses.