Write an expression for the equilibrium constant of each chemical equation.
a. SbCl₅(g) ⇌ SbCl₃(g) + Cl₂(g)
b.2 BrNO(g) ⇌ 2 NO(g) + Br₂(g)
c. CH₄(g) + 2 H₂S(g) ⇌ CS₂(g) + 4 H₂(g)
d. 2 CO(g) + O₂(g) ⇌ 2 CO₂(g)

Key Concepts

Equilibrium Constant (K)

The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given chemical reaction. It is specific to a particular reaction at a certain temperature and provides insight into the extent to which a reaction proceeds. A larger K value indicates a greater concentration of products at equilibrium, while a smaller K suggests that reactants are favored.

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products over time. At this point, the system is in a state of balance, and no net change is observed. Understanding this concept is crucial for writing equilibrium expressions, as it highlights the dynamic nature of reactions.

Writing Equilibrium Expressions

To write an equilibrium expression for a chemical reaction, the general form is K = [products]^coefficients / [reactants]^coefficients, where the brackets denote the molar concentrations of the species involved. For the reaction given, SbCl5(g) ∆ SbCl3(g) + Cl2(g), the equilibrium expression would be K = [SbCl3][Cl2] / [SbCl5]. This expression reflects the relationship between the concentrations of the reactants and products at equilibrium.