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

• A. Adding a catalyst
• B. Decreasing the concentration of reactants
• C. Increasing the surface area of a solid reactant
• 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 and energy of collisions between reactant molecules.
2. Recall that adding a catalyst provides an alternative reaction pathway with a lower activation energy, which increases the reaction rate.
3. Recognize that increasing the surface area of a solid reactant exposes more particles to react, increasing the frequency of collisions and thus the reaction rate.
4. Know that increasing the temperature increases the kinetic energy of molecules, leading to more frequent and energetic collisions, which increases the reaction rate.
5. Identify that decreasing the concentration of reactants reduces the number of particles available to collide, thereby decreasing the reaction rate, so this factor would NOT increase the rate.