What does the equilibrium constant expression represent?

The equilibrium constant expression represents the ratio of the concentrations of products to the concentrations of reactants, each raised to the power of their respective coefficients in the balanced chemical equation, at equilibrium. This means that at equilibrium, the constant provides insight into the relative amounts of reactants and products in a chemical reaction.

For a general reaction of the form:

[ aA + bB \leftrightarrow cC + dD ]

the equilibrium constant ( K ) is expressed as:

[ K = \frac{[C]^c [D]^d}{[A]^a [B]^b} ]

Here, the brackets represent the molar concentrations of the chemical species. This expression quantitatively describes the state of a reaction at equilibrium, giving an idea of how far the reaction has proceeded towards products or reactants. If ( K ) is large, the reaction favors products; if ( K ) is small, the reactants are favored.

The other options do not accurately capture the essence of the equilibrium constant expression. It does not represent the rate of reaction—reaction rates are represented by different expressions involving activation energy and concentration changes over time. The maximum yield of products is not a fixed quantity per the equilibrium constant,