Which statement best describes chain branching in radical reactions?

• A. It slows the reaction by consuming radicals
• B. It has no effect on the rate
• C. It accelerates the reaction by generating more radicals
• D. It halts chain reactions

Answer: (C)

Chain branching occurs when a single radical reaction step creates more radicals than it consumes. Because the rate of radical-chain reactions depends on how many radicals are present, generating additional radicals speeds up the propagation steps and raises the overall rate. This positive feedback can lead to a rapid increase in reaction speed, sometimes dramatically, as the radical pool grows. In contrast, if branching didn’t add new radicals, the rate would stay limited by the existing radical concentration. Branching thus accelerates the reaction by increasing the number of radicals available to drive subsequent steps.