17. Acid and Base Equilibrium

Which Bronsted-Lowry base has the greatest concentration of hydroxide ions? 

Determine the pK_a given the Kb of the following bases:

i) NH₃               K_b = 1.76 × 10⁻⁵ ; NH₄⁺           pK_a = ____________

ii) C₆H₅NH₂     K_b = 3.9 × 10⁻¹⁰ ; C₆H₅NH₃⁺  pK_a = ____________

Hypobromous acid (K_a = 2.8 × 10⁻⁹) and hydrocyanic acid (K_a = 4.9 × 10⁻¹⁰) are both weak acids. Determine if reactants or products are favored in the following reaction.

HBrO (aq) + CN⁻ (aq) ⇌ BrO⁻ (aq) + HCN (aq)

a) reactants        b) products            c) both directions are favored equally   d) neither direction is favored