Equilibrium

Review Packet

Objectives:

• Write equilibrium expressions for a given reaction
• Calculate Q (reaction quotient) and compare it to K to determine if a reaction is at equilibrium
• Manipulate K if a reaction is reversed or multiplied by a coefficient
• Calculate K from given equilibrium concentrations, or if given K and all except one equilibrium concentrations, solve for the missing value
• Calculate equilibrium concentrations (or one of the missing variables) if given any two of the following values: K, the initial concentrations, one equilibrium concentration
• Do calculations involving gaseous equilibrium, partial pressures, and K_p
• Know relationship between K and K_p
• Use LeChatlier’s principle to determine in what direction the position of equilibrium will shift when a change is imposed
• Calculate the value of K from thermodynamic values such as ΔG°
• The solubility-product constant, K_sp
• Solubility
• Ion Product
• Factors affecting solubility
• Complex Ions
• Coordination Complexes
• Nomenclature of Coordination Complexes

Chapters 15, 17, 18, 19, 23

Equations and Constants (on yellow sheet)

Q = ([C]^c[D]^d) / ([A]^a[B]^b) where aA + bB à cC + dD 14 = pH + pOH

K_a = [H⁺][A^-] / [HA] pH = pK_a + log [A^-]/[HA]

K_b = [OH^-] [HB⁺]/[B] pOH = pK_b + log [HB⁺]/[B]

K_w = [OH^-][H⁺] = 10^-14 @ 25° C = K_a x K_b pK_a= - log K_a; pK_b = - log K_b

pH = - log [H⁺], pOH = - log [OH^-] K_p = K_c(RT)^Δn, where Δn = moles product gas-moles reactant gas

Notes

AP TIP

The first Free Response question is always an equilibrium problem and it is worth 20% of your free response grade.

--College Board Website

I. Equilibrium Constant

A. K or K_c

B. K_p

C. Equilibrium Expression

D. Relationship between K_c & K_p

E. Calculations involving K_c

II. Reaction Quotient

A. Expression

B. Compare Q to K

III. Types of Equilibrium Problems

A. Manipulation of the equilibrium constant

1. Reaction is reversed

2. Coefficients in a balanced equation are multiplied by a number, n

B. If given all equilibrium concentrations, calculate K

C. If given a value of K, and all but one of the equilibrium concentrations

D. If given the value of the initial concentrations of the reactants and one of the equilibrium concentrations of either the reactants or products

E. If given the initial concentrations and the value of K, solve by approximation for the equilibrium concentrations

IV. LeChâtlier’s Principle

A. Effects of changing concentration

B. Effects of changing pressure

C. Effects of changing temperature

D. Catalysis

V. Relationship of K to Free Energy

VI. Solubility Product Constant

A. Solubility

B. Ion Product

C. Factors that affect solubility

D. Common-Ion effect

E. Effect of pH on solubility

VII. Complex Ions

A. Amphoterism

B. Coordination Complexes

C. Nomenclature of coordination complexes