Use particle models to explain why increasing concentration increases the rate of reaction.

Use particle models to explain why increasing concentration increases the rate of reaction.

• A. As the concentration of the reactants increases, more particles are in a given amount of space and there will be more frequent collisions between particles.
• B. The temperature rises.
• C. The product is formed.
• D. The solvent is removed.

Answer: (A)

Increasing concentration raises the rate of reaction because the particle model shows that there must be collisions between reacting particles for a reaction to happen. When you pack more particles into the same volume, they collide with each other more often per unit time. Each collision has a chance of leading to a reaction only if the particles have enough energy to overcome the activation energy and are oriented properly. So, raising concentration increases the number of collisions, and since the proportion of collisions that are effective depends on energy and orientation (not on the concentration itself), the overall number of successful collisions rises, speeding up the reaction. This explanation focuses on collision frequency as the main driver; changing temperature, forming products, or removing solvent aren’t what’s being invoked to explain the concentration effect.

Increasing concentration raises the rate of reaction because the particle model shows that there must be collisions between reacting particles for a reaction to happen. When you pack more particles into the same volume, they collide with each other more often per unit time. Each collision has a chance of leading to a reaction only if the particles have enough energy to overcome the activation energy and are oriented properly. So, raising concentration increases the number of collisions, and since the proportion of collisions that are effective depends on energy and orientation (not on the concentration itself), the overall number of successful collisions rises, speeding up the reaction. This explanation focuses on collision frequency as the main driver; changing temperature, forming products, or removing solvent aren’t what’s being invoked to explain the concentration effect.