Which one of the following would NOT increase the rate of a chemical reaction?

• A. Increasing the surface area of a solid reactant
• B. Decreasing the concentration of reactants
• C. Adding a catalyst
• D. Increasing the temperature

Answer: (B)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on factors that increase the frequency or energy of collisions between reactant molecules.
2. Recognize that increasing the surface area of a solid reactant exposes more particles to react, thus increasing the reaction rate.
3. Know that adding a catalyst provides an alternative reaction pathway with a lower activation energy, which increases the reaction rate.
4. Recall that increasing the temperature increases the kinetic energy of molecules, leading to more frequent and energetic collisions, thereby increasing the reaction rate.
5. Identify that decreasing the concentration of reactants reduces the number of particles available to collide, which decreases the reaction rate, so this would NOT increase the rate.