Why does increasing the concentration of reactants generally make a chemical reaction proceed faster?

• A. It increases the temperature of the reaction mixture.
• B. It decreases the activation energy required for the reaction.
• C. It changes the reaction from endothermic to exothermic.
• D. It increases the frequency of collisions between reactant particles.

Answer: (D)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on how often reactant particles collide with enough energy to react.
2. Recall the collision theory, which states that for a reaction to occur, reactant particles must collide with sufficient energy and proper orientation.
3. Recognize that increasing the concentration of reactants means there are more particles in a given volume, which leads to more frequent collisions.
4. Note that more frequent collisions increase the chances of successful collisions per unit time, thereby increasing the reaction rate.
5. Conclude that increasing reactant concentration does not change temperature, activation energy, or reaction enthalpy, but primarily increases the frequency of effective collisions.