Write the expression for 𝐾𝑐 for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.
(e) 2Ag(𝑠) + Zn2⁺(𝑎𝑞) ⇌ 2 Ag⁺(𝑎𝑞) + Zn(𝑠)

Key Concepts

Equilibrium Constant (Kc)

The equilibrium constant, Kc, is a numerical value that expresses the ratio of the concentrations of products to the concentrations of reactants at equilibrium for a given reaction at a specific temperature. It is calculated using the formula Kc = [products]^[coefficients] / [reactants]^[coefficients]. Understanding Kc is essential for predicting the direction of a reaction and the extent to which reactants are converted to products.

Homogeneous vs. Heterogeneous Reactions

Homogeneous reactions occur when all reactants and products are in the same phase (solid, liquid, or gas), while heterogeneous reactions involve reactants and products in different phases. This distinction is important because it affects how concentrations are expressed in the Kc expression. In heterogeneous reactions, only the concentrations of species in the aqueous or gaseous phase are included in the Kc expression, while solids and liquids are omitted.

Phase Representation in Reactions

In chemical equations, the physical state of each substance is indicated by symbols: (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous solutions. This representation is crucial for determining the correct form of the Kc expression. For example, in the given reaction, only the aqueous ions are included in the Kc expression, as the solid metals do not contribute to the equilibrium concentrations.