Question

A particular reaction has an equilibrium constant of Kp = 0.50. A reaction mixture is prepared in which all the reactants and products are in their standard states. In which direction will the reaction proceed?

Answer 1

With an equilibrium constant (Kp) of 0.50 and the reactants and products initially in their standard states, the reaction will proceed in the forward direction to reach equilibrium, since the initial reaction quotient (Q) will be less than Kp.

Step-by-step explanation:

The student has asked to predict the direction in which a reaction with an equilibrium constant of Kp = 0.50 will proceed if all reactants and products are in their standard states. Understanding the concept of equilibrium allows us to interpret this value of Kp. The equilibrium constant (Kp) indicates the ratio of partial pressures of products to reactants at equilibrium. A Kp value of less than 1, as in this case, suggests that the reactants are favored at equilibrium.

If the reaction mixture is initially prepared with all components in their standard states, we must consider the reaction quotient (Q). At the start, Q is zero since there are no products yet. Since Q < Kp (which is 0.50 in this case), the reaction will proceed in the forward direction to produce more products and reach equilibrium where Q will equal Kp.

Note that if the reaction involved gases, the number of moles of gaseous reactants and products could further impact the relationship between Kp and Kc via changes in pressure and volume as described by the equation Kp = K(RT)Δn.