Chemical Equilibrium and Equilibrium Constant:

Chemical equilibrium occurs when the rate of the forward reaction is equal to the rate of the reverse reaction. In a chemical equilibrium, the concentrations of reactants and products remain constant over time.

The equilibrium constant (K) is a mathematical expression that relates the concentrations of reactants and products at equilibrium. It is defined as the ratio of the product concentrations to the reactant concentrations, each raised to the power of their respective stoichiometric coefficients.

Giving the Given Information:

In the given chemical equilibrium A + B ⇌ C + D, it is stated that when one mole of each of the two reactants (A and B) are mixed, 0.6 mole each of the products (C and D) are formed.

This information allows us to determine the concentrations of reactants and products at equilibrium.

Calculating Equilibrium Concentrations:

Let's assume that the initial concentration of A and B is x mol/L. Since one mole of each reactant is mixed, the initial concentration of A and B is equal.

At equilibrium, the concentration of A will be (x - 0.6) mol/L (one mole of A has reacted to form 0.6 mole of product C), and the concentration of B will also be (x - 0.6) mol/L.

Similarly, the concentrations of C and D at equilibrium will be 0.6 mol/L each (as 0.6 mole of each product is formed).

Writing the Equilibrium Expression:

The equilibrium expression for the given chemical equilibrium is:

K = [C]^c[D]^d / [A]^a[B]^b

where [A], [B], [C], and [D] are the concentrations of A, B, C, and D at equilibrium, respectively, and a, b, c, and d are the stoichiometric coefficients of A, B, C, and D in the balanced chemical equation.

Since one mole of each reactant forms 0.6 mole of each product, the stoichiometric coefficients of A, B, C, and D are all 1.

Calculating the Equilibrium Constant:

Substituting the equilibrium concentrations into the equilibrium expression, we get:

K = (0.6)^1 * (0.6)^1 / (x - 0.6)^1 * (x - 0.6)^1

Simplifying the expression, we have:

K = 0.36 / (x - 0.6)^2

Therefore, the equilibrium constant (K) for the given chemical equilibrium can be calculated using the above expression.

Conclusion:

In summary, the equilibrium constant (K) for the chemical equilibrium A + B ⇌ C + D can be calculated by determining the concentrations of reactants and products at equilibrium and substituting them into the equilibrium expression. The given information of one mole of each reactant forming 0.6 mole of each product allows us to determine the equilibrium concentrations and subsequently calculate the equilibrium constant.