Question

which one of the following factors will decrease (slow down) the rate of a chemical reaction? reducing the surface area of solid reactants. increasing the concentration of the reactants. increasing the temperature of the system.

Explanation:

To determine the factor that decreases the rate of a chemical reaction, we analyze each option:

• Reducing the surface area of solid reactants: For solid reactants, a smaller surface area means fewer reactant particles are exposed to collide, so the reaction rate decreases.
• Increasing the concentration of reactants: Higher concentration means more reactant particles per unit volume, leading to more frequent collisions and a faster reaction rate.
• Increasing the temperature of the system: Higher temperature increases the kinetic energy of particles, causing more frequent and energetic collisions, which speeds up the reaction.

So, reducing the surface area of solid reactants slows down the reaction rate.

Answer:

A. Reducing the surface area of solid reactants.