What is the definition of polymerization?

• A. A chemical process where larger molecules are broken down into smaller ones
• B. A reaction where small molecules combine into larger ones, releasing heat and pressure
• C. A process of mixing different chemical compounds together
• D. A type of physical change in matter

Answer: (B)

Polymerization is best defined as a reaction where small molecules, known as monomers, combine to form larger molecules called polymers. This process often involves the release of energy in the form of heat and can generate pressure as the newly formed polymer chains grow in size. This distinctive characteristic of polymerization sets it apart from other chemical processes where the focus might be on breaking down substances or mere mixing of compounds without the transformation into a new structure.

In contrast, breaking down larger molecules into smaller ones is referred to as decomposition, and does not align with the definition of polymerization. The definition involving mixing different compounds pertains more to solutions and not specifically to the formation of polymers. Lastly, polymerization is a chemical change rather than a physical change, as it results in entirely new chemical substances being formed from the reactants. Hence, the correct choice encapsulates the essence of polymerization accurately.