The effect of a catalyst on an equilibrium is to __. A. increase the equilibrium constant so that products are favored B. slow the reverse reaction only C. increase the rate of the forward reaction only D. shift the equilibrium to the right E. increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture
The correct answer and explanation is:
The correct answer is E. increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture.
A catalyst works by lowering the activation energy for both the forward and reverse reactions. This allows both reactions to proceed at a faster rate, but it does not alter the position of the equilibrium or the equilibrium constant. It simply speeds up the process of reaching equilibrium.
To explain in more detail, when a chemical reaction occurs, the reactants must reach a certain energy threshold, called the activation energy, to be transformed into products. A catalyst provides an alternative reaction pathway with a lower activation energy, which speeds up the reaction. However, it does not change the energies of the reactants or the products themselves, meaning the equilibrium constant remains unchanged. As a result, the catalyst accelerates both the forward and reverse reactions equally, allowing the system to reach equilibrium faster but not altering the final concentrations of reactants and products.
For example, in a reversible reaction, without a catalyst, the system may take a long time to reach equilibrium. With a catalyst, the system reaches equilibrium much more quickly, but the ratio of products to reactants at equilibrium is the same as it would be without the catalyst. The catalyst does not “favor” the forward or reverse reaction in terms of equilibrium position; it only affects how quickly the system gets there.
In summary, a catalyst has no impact on the final concentration of products and reactants at equilibrium, and it does not shift the equilibrium. It simply accelerates the process of achieving equilibrium, which makes it valuable in industrial applications where the speed of reaching equilibrium can be crucial.