A catalyst: Alters the equilibrium constant Increases the equilibrium concentration of products Helps establish the equilibrium quickly Supplies energy to the reactants

A catalyst is a substance that increases the rate of a reaction by decreasing its activation energy. This means that it lowers the energy barrier that reactants need to overcome to form products, allowing the reaction to proceed more quickly.

Key Points:

1. A catalyst does not alter the equilibrium constant of a reaction.
2. It does not increase the equilibrium concentration of products.
3. It helps establish the equilibrium quickly by speeding up both the forward and backward reactions.
4. A catalyst does not supply energy to the reactants; instead, it provides an alternative pathway with a lower activation energy.

Detailed Explanation:

Consider a reaction between substances $A$ and $B$ to form products $C$ and $D$, represented as $A + B \rightarrow C + D$. The reaction can be visualized on a potential energy diagram plotting potential energy against the progress of the reaction.

• Without a catalyst: The reactants $A$ and $B$ need to overcome a high activation energy barrier to form products $C$ and $D$.
• With a catalyst: The activation energy barrier is reduced, thus the reaction rate increases.

In equilibrium reactions, a catalyst accelerates both the forward and reverse reactions equally, helping the system to reach equilibrium faster without being consumed in the reaction.

Correct Answer:

The catalyst helps establish the equilibrium quickly.

Hence, the most accurate statement about a catalyst among the given options is:

Option C: "Helps establish the equilibrium quickly."