What information does an equilibrium constant give about a reaction?
A. It tells how long it takes the reaction to reach equilibrium.
B. It tells how much energy is required for the reaction to happen.
C. It tells what the rate constant of the reaction is at equilibrium.
D. It tells whether products or reactants are favored at equilibrium.
The correct answer is D. An equilibrium constant provides information about the relative amounts of products and reactants that are present at equilibrium. Specifically, it indicates whether the products or the reactants are favored.
To calculate the equilibrium constant, you need the balanced chemical equation for the reaction. The equilibrium constant is expressed as the ratio of the concentrations of the products raised to their stoichiometric coefficients, divided by the concentrations of the reactants also raised to their stoichiometric coefficients. The concentrations used in the equilibrium constant expression should be in terms of molarity (moles per liter).
For example, if the balanced chemical equation for a reaction is A + B -> C + D, the equilibrium constant expression would be K = [C]^c[D]^d / [A]^a[B]^b, where [C], [D], [A], and [B] represent the molar concentrations of the respective species, and c, d, a, and b represent their stoichiometric coefficients.
The value of the equilibrium constant determines whether the reaction is product-favored or reactant-favored at equilibrium. If the equilibrium constant is greater than 1, it means that the concentration of products is higher than the concentration of reactants at equilibrium, indicating that the reaction is product-favored. If the equilibrium constant is less than 1, it means that the concentration of reactants is higher than the concentration of products at equilibrium, indicating that the reaction is reactant-favored. If the equilibrium constant is equal to 1, it means that the concentration of products and reactants at equilibrium are equal, indicating that the reaction is at equilibrium with no net change in concentrations.
Therefore, the equilibrium constant provides valuable information about the direction and extent to which a reaction proceeds at equilibrium.