Which of the following changes would increase the rate of a chemical reaction?

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

Answer: (D)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on factors such as concentration, temperature, surface area, and the presence of catalysts.
2. Analyze the effect of adding an inert gas at constant volume: Since the volume is constant, the partial pressures (or concentrations) of reactants do not change, so the reaction rate remains essentially unchanged.
3. Consider decreasing the concentration of reactants: Lowering reactant concentration reduces the frequency of effective collisions, thus decreasing the reaction rate.
4. Examine lowering the surface area of a solid reactant: Reducing surface area decreases the available area for collisions, which lowers the reaction rate.
5. Recognize that increasing the temperature increases the kinetic energy of molecules, leading to more frequent and energetic collisions, thereby increasing the reaction rate.