Practice: Provide K expression for the reverse of the following reaction:
Fe2O3(s) + 3 H2(g) ⇌ 2 Fe(s) + 3 H2O(g)
Equilibrium Constant (K) specifies the favored direction of a reaction.
Equilibrium Constant
Concept #1: Equilibrium Constant (K) Concept 1
Concept #2: Equilibrium Constant Expressions
Solids and pure liquids are excluded from Equilibrium Expressions.
Example #1: What is the equilibrium constant expression for the following reaction:
2 HgO (s) + H2O (l) + 2 Cl2 (g) ⇌ 2 HOCl (aq) + HgO (s) + HgCl2 (s)
Concept #3: Magnitude of Equilibrium Constant
Magnitude of Equilibrium Constant (K) indicates how far right or left a reaction lies at equilibrium. This allows us to determine if more products or reactants exist at equilibrium.
Example #2: When this reaction comes to an equilibrium, which will be higher in pressure, reactants or products?
2 CH4 (g) + 2 H2S (g) ⇌ CS2 (g) + 4 H2 (g) Kp = 1.3 x 103
a) reactants b) products c) neither d) impossible to estimate
Practice: Which of the reactions is likely to produce more O2 at equilibrium at 25°C?
Practice: Consider the reaction A(g) ⇌ B(g) + C(g), with kforward of 5.7 x 10–2 and kreverse of 3.8 x 10–4. Which would be greater at equilibrium, partial pressure of A or partial pressures of B and C?
