Unit 7: Topic 2 - Direction of Reversible Reactions

Question 1

Intuitively state and explain a timeline of what occurs in a chemical reaction if initially, the forward reaction rate is greater than the reverse reaction rate.

Answer 1

Recall from kinetics that the reaction rate depends on the reactants’ concentration. Initially, since the forward reaction rate is greater, the forward reaction will proceed faster than the reverse reaction, and there will be a net conversion from reactants to products. This net forward reaction will continue for a while, and the concentration of the reactants will diminish. Eventually, the concentrations of the reactants are low enough so that the rate of the forward reaction is no longer greater than the rate of the reverse reaction. At this point, the reaction will achieve equilibrium. The timeline is similar if the reverse reaction rate is initially greater; the only difference is that the reverse reaction rate decreases, and the forward reaction rate increases.