Make two chemical solutions and mix them together. Wait a few seconds, then wow! It will suddenly change colors. This is the famous iodine clock reaction in an easy-to-use kit. Change the concentrations or temperature and change the delay for the color change. Do the clock reaction with Eco-foam. Learn about solutions and rates of reaction (kinetics). Contains starch solution. sodium iodate, sodium sulfite, citric acid, sodium thiosulfate, eco-foam, spoons, small scoops, cups, rack, and instructions.