Chemical Equilibrium — 60 Terms Defined

Equilibrium Position Chemical Equilibrium mol/L The particular set of concentrations at which a system settles, describing how far the reaction has proceeded.

Equilibrium Yield Chemical Equilibrium Dimensionless The proportion of reactant converted to product once equilibrium has been reached. yield = n_product / n_theoretical

Extent of Reaction Chemical Equilibrium mol A single variable measuring how far a reaction has progressed from pure reactants towards products. ξ = (n_i − n_i°) / ν_i

Heterogeneous Equilibrium Chemical Equilibrium Dimensionless An equilibrium involving species present in more than one phase.

Homogeneous Equilibrium Chemical Equilibrium Dimensionless An equilibrium in which all the reacting species are present in the same phase.

ICE Table Chemical Equilibrium mol/L A systematic tabulation of Initial, Change and Equilibrium amounts used to solve equilibrium problems.

Ionic Equilibrium Chemical Equilibrium mol/L An equilibrium involving ions in solution, such as the dissociation of weak electrolytes or the dissolution of sparingly soluble salts.

Ionic Product Chemical Equilibrium Various The product of the ion concentrations actually present in a solution, each raised to its stoichiometric power. Q_sp = [A⁺]^m[B⁻]^n

Ionic Strength Chemical Equilibrium mol/L A measure of the total concentration of ionic charge in a solution. I = ½ Σ c_i z_i²

Law of Mass Action Chemical Equilibrium Various The principle that the rate of a reaction is proportional to the product of the active masses of the reactants. K = [C]^c[D]^d / [A]^a[B]^b

Le Chatelier's Principle Chemical Equilibrium Dimensionless When a system at equilibrium is disturbed, it responds in the direction that partially opposes the disturbance.

Magnitude of K and Extent of Reaction Chemical Equilibrium Dimensionless The use of the size of the equilibrium constant to judge how far a reaction proceeds before equilibrium is reached. K ≫ 1: products favoured

Mole Fraction Equilibrium Constant Chemical Equilibrium Dimensionless The equilibrium constant written in terms of the mole fractions of the reacting gases. Kx = Kp × p^(−Δn)

Optimum Conditions for Industrial Yield Chemical Equilibrium Various The compromise set of temperature, pressure and catalyst chosen to balance equilibrium yield against reaction rate and cost.

Overall Formation Constant Chemical Equilibrium Various The equilibrium constant for the formation of a complex directly from the free metal ion and all its ligands. β_n = K₁K₂ … K_n

Partition Coefficient Chemical Equilibrium Dimensionless The equilibrium ratio of a solute's concentrations in two immiscible phases. P = C₁ / C₂

Perturbation and Re-equilibration Chemical Equilibrium s The disturbance of an equilibrium followed by its relaxation to a new equilibrium state.

Phase Equilibrium Chemical Equilibrium Dimensionless The condition in which two or more phases of a substance coexist with no net transfer between them. μ_phase1 = μ_phase2

Physical Equilibrium Chemical Equilibrium Dimensionless An equilibrium between two physical states or phases of the same substance. H₂O(l) ⇌ H₂O(g)

Predicting Precipitation Chemical Equilibrium Dimensionless The use of the ionic product and solubility product to decide whether a solid will form on mixing two solutions. Q_sp > Ksp → precipitate

Pressure Equilibrium Constant Chemical Equilibrium Various The equilibrium constant for a gaseous reaction expressed in terms of partial pressures. Kp = p_C^c p_D^d / p_A^a p_B^b

Reaction Quotient Chemical Equilibrium Various The same ratio as the equilibrium constant but evaluated with the concentrations actually present at any moment. Q = [C]^c[D]^d / [A]^a[B]^b

Relationship between K and Rate Constants Chemical Equilibrium Various The equilibrium constant of an elementary reaction equals the ratio of its forward and reverse rate constants. K = k_forward / k_reverse

Relationship between Kp and Kc Chemical Equilibrium Dimensionless The conversion linking the pressure and concentration forms of the equilibrium constant for a gaseous reaction. Kp = Kc(RT)^Δn