The diagram shown here represents the equilibrium state for the reaction A2(𝑔) + 2B(𝑔) ⇌ 2AB(𝑔). (a) Assuming the volume is 2 L, calculate the equilibrium constant 𝐾𝑐 for the reaction.

Verified step by step guidance

1. Step 1: Identify the equilibrium concentrations of the reactants and products from the diagram. The number of molecules of each species in the diagram represents the number of moles of that species. Divide the number of moles by the volume (2 L) to get the molar concentration.
2. Step 2: Write the expression for the equilibrium constant, Kc, for the reaction. For the reaction A2(g) + 2B(g) ⇌ 2AB(g), the equilibrium constant expression is Kc = [AB]^2 / ([A2][B]^2).
3. Step 3: Substitute the equilibrium concentrations from Step 1 into the equilibrium constant expression from Step 2. Remember that the concentrations should be in moles per liter (M).
4. Step 4: Perform the calculations as indicated in the equilibrium constant expression. Remember to square the concentration of AB and B as indicated in the equilibrium constant expression.
5. Step 5: The result of these calculations is the equilibrium constant, Kc, for the reaction. This value indicates the extent to which the reaction proceeds to the right (towards the products) at equilibrium.

Key Concepts

Equilibrium Constant (Kc)

The equilibrium constant, Kc, is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. It is calculated using the formula Kc = [products]^[coefficients] / [reactants]^[coefficients]. A Kc value greater than 1 indicates that products are favored at equilibrium, while a value less than 1 suggests that reactants are favored.

Concentration

Concentration refers to the amount of a substance (solute) present in a given volume of solution. It is typically expressed in moles per liter (Molarity, M). In equilibrium calculations, the concentrations of the reactants and products at equilibrium are essential for determining the value of Kc, as they directly influence the ratio used in the equilibrium expression.

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It involves using the coefficients from the balanced chemical equation to relate the amounts of substances consumed and produced. In the context of equilibrium, stoichiometry is crucial for determining the concentrations of reactants and products based on their initial amounts and the changes that occur as the system reaches equilibrium.