Which of the following factors increases the rate of a chemical reaction?

• A. Increasing the concentration of reactants
• B. Decreasing the temperature
• C. Lowering the surface area of a solid reactant
• D. Adding an inert gas at constant volume

Answer: (A)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on how often and how effectively reactant particles collide with each other.
2. Recall that increasing the concentration of reactants increases the number of particles in a given volume, which leads to more frequent collisions and thus increases the reaction rate.
3. Recognize that decreasing the temperature reduces the kinetic energy of particles, causing fewer effective collisions and therefore decreases the reaction rate.
4. Know that lowering the surface area of a solid reactant reduces the area available for collisions, which decreases the reaction rate.
5. Understand that adding an inert gas at constant volume does not change the concentration of reactants or their collision frequency, so it does not affect the reaction rate.