Describe the differences between the reaction quotient and equilibrium constant.

The reaction quotient and equilibrium constant are both measures of a chemical reaction's progress towards equilibrium, but they differ in their calculation and meaning.

The reaction quotient (Q) is calculated using the same formula as the equilibrium constant (K), but with the concentrations of reactants and products at any given time during the reaction, rather than at equilibrium. Q can be used to predict the direction in which a reaction will proceed, based on whether it is greater than or less than K. If Q is greater than K, the reaction will shift towards the reactants to reach equilibrium, while if Q is less than K, the reaction will shift towards the products.

The equilibrium constant (K) is a measure of the ratio of products to reactants at equilibrium, and is calculated using the concentrations of reactants and products at that point. K is a constant value for a given reaction at a given temperature, and is independent of the initial concentrations of reactants and products. K can be used to calculate the concentrations of reactants and products at equilibrium, and to compare the relative strengths of acids and bases.

In summary, the reaction quotient and equilibrium constant are both important measures of a chemical reaction's progress towards equilibrium, but differ in their calculation and meaning. Q is based on concentrations at any given time during the reaction, and can be used to predict the direction of the reaction, while K is based on concentrations at equilibrium, and is a constant value for a given reaction at a given temperature.