Advanced Placement (AP) Chemistry Practice Exam

The rate of a chemical reaction is influenced by several key factors, including concentration, temperature, surface area, and the presence of a catalyst.

When we look at concentration, an increase typically raises the number of reactive particles in a given volume, leading to a higher frequency of collisions between reactant molecules. This increase in collisions generally accelerates the reaction.

Temperature plays a significant role as well; raising the temperature increases the kinetic energy of the molecules involved. Higher energy means that molecules move faster, collide more often, and collide with greater energy, which can overcome the activation energy barrier more effectively, leading to an increased rate of reaction.

Surface area is another important factor, especially for solid reactants. A larger surface area means that more particles are available to collide with other reactants. This is why powdered solids react more quickly than larger chunks.

Finally, a catalyst is a substance that increases the reaction rate without being consumed in the process. Catalysts work by providing an alternative pathway for the reaction with a lower activation energy, making it easier for reactants to convert into products.

Together, these four factors—concentration, temperature, surface area, and the presence of a catalyst—play vital roles in determining how quickly a reaction occurs. Understanding these