What is the effect of adding a catalyst to a reaction in aqueous solution?

When a catalyst is added to a reaction in an aqueous solution, it provides an alternative pathway for the reaction to occur. This alternative pathway has a lower activation energy compared to the uncatalyzed reaction. As a result, more reactant molecules have sufficient energy to overcome this lower energy barrier, allowing the reaction to proceed more quickly.

In essence, a catalyst increases the rate of the reaction by enhancing the likelihood of reactant collisions leading to successful outcomes. It does so without being consumed in the reaction, meaning that it can facilitate many reactions over time. This is why the answer indicates that a catalyst increases the reaction rate.