Why does the reaction rate increase as the temperature increases toward the optimum temperature?

• A. Because the products become more stable at higher temperatures.
• B. Because the activation energy of the reaction decreases as temperature increases.
• C. Because more reactant molecules have enough kinetic energy to overcome the activation energy barrier.
• D. Because the concentration of reactants increases with temperature.

Answer: (C)

Verified step by step guidance

1. Understand that reaction rate depends on how often and how effectively reactant molecules collide with enough energy to react.
2. Recall that temperature is a measure of the average kinetic energy of molecules; as temperature increases, molecules move faster.
3. Recognize that only molecules with kinetic energy equal to or greater than the activation energy can successfully react.
4. Know that increasing temperature increases the fraction of molecules with sufficient energy to overcome the activation energy barrier, according to the Arrhenius equation: \(k = A e^{-\frac{E_a}{RT}}\) where \(k\) is the rate constant, \(E_a\) is activation energy, \(R\) is the gas constant, and \(T\) is temperature in Kelvin.
5. Conclude that the reaction rate increases with temperature because more molecules have enough energy to surpass the activation energy, not because activation energy decreases or reactant concentration changes.