What does a very small equilibrium constant (K << 1) indicate about a chemical reaction at equilibrium?

• A. The reaction proceeds nearly to completion, favoring product formation.
• B. The concentration of products is much greater than the concentration of reactants.
• C. The reaction mixture contains equal concentrations of reactants and products.
• D. The concentration of reactants is much greater than the concentration of products.

Answer: (D)

Verified step by step guidance

1. Recall that the equilibrium constant \(K\) is defined as the ratio of the concentrations of products to reactants at equilibrium, raised to the power of their stoichiometric coefficients: \[K = \frac{[\text{products}]^{coefficients}}{[\text{reactants}]^{coefficients}}\]
2. Understand that when \(K\) is very small (much less than 1), it means the numerator (products) is much smaller than the denominator (reactants), indicating that the concentration of products is low compared to reactants at equilibrium.
3. Interpret this to mean the reaction favors the reactants, so the reaction does not proceed significantly toward product formation and remains mostly on the reactant side.
4. Contrast this with a large \(K\) (much greater than 1), which would indicate the reaction favors products and proceeds nearly to completion.
5. Therefore, a very small equilibrium constant \(K \ll 1\) indicates that at equilibrium, the concentration of reactants is much greater than the concentration of products.