Which factor is least associated with the risk of a runaway reaction?

• A. Rate of heat generation
• B. Color of the reactants
• C. Heat removal capability
• D. Temperature of reactants

Answer: (B)

The main idea is that a runaway reaction is driven by the heat balance: how fast heat is generated versus how quickly it can be removed, and how sensitive the reaction rate is to temperature. If the reaction is highly exothermic and heat removal is limited, the temperature rises, which speeds up the reaction even more, producing more heat in a dangerous loop. The temperature of the reactants matters because starting hotter speeds up the reaction rate (Arrhenius behavior) and makes runaway more likely.

The color of the reactants, on the other hand, does not affect exothermicity, reaction kinetics, or heat transfer. It’s just a visual property and does not change how much heat is produced, how easily heat is removed, or how temperature influences the reaction rate. So color is not related to runaway risk.