Chemical Reactions, Grades 9-12 Chemical reactions occur all around us, including in the making of this craft foam. Chemical reactions may release or consume energy. The formation of polyurethane undertaken in this activity is an exothermic reaction. The condensation polymerization reaction encountered in this activity involves the formation of free radicals. Reaction rates depend upon how often the reacting atoms and molecules encounter one another, on the temperature, and on the properties of the reacting species.
Catalysts accelerate chemical reactions.
Structure and Properties of Materials, Grades 9-12 Solids, liquids, and gases differ in the distances between molecules. The growth of the foam to about 30 times its original volume is caused by the liquid blowing agent in the mixture being vaporized. Page maintained by Steve Gentle, Research Associate.