WARM UP For the reaction Br2(aq) + I2(aq) 2IBr(aq), equilibrium concentrations are .108M for Br2, .34M for I2, and .472M for IBr. What is K? Is the reaction product-favored or reactant-favored? Using the same reaction equation, if you begin with 2.5 M of each reactant, and have 1.1 M remaining at equilibrium, how much product would you have formed?

Acid/Base Ionization

Strong vs. Weak Strong acids and bases Completely ionize (dissociate) in water HCl  H+ + Cl- Every bit of reactant becomes acid or base 2 M HCl = 2M H+ (acid)

Strong vs. Weak Weak acids and bases Do not completely ionize Equilibrium between reactant and products CH3COOH H+ + CH3COO- Smaller than expected amount of acid or base Percent ionization Ratio of H+ / CH3COOH K value Ka (acids) or Kb (bases)

Weak Acids/Bases Calculate K for the ionization if you know concentrations at equilibrium Ka x Kb = Kw Greater the K value, stronger the acid or base More H+ or OH- product Ex: NH3 + H2O NH4+ + OH- Kb = [NH4+] [OH-] [NH3]

ICE and K Calculating K Ex: .1 M HCOOH (pH = 2.39) You often only know pH and Initial concentration Equilibrium[H+] or [OH-] determined by pH H+ = 10-pH OH-=10-pOH pH + pOH = 14 ICE Table to get values for K Ex: .1 M HCOOH (pH = 2.39)

WARM UP A .100 M solution of chloroacetic acid (ClCH2COOH) has a pH of 1.95. Calculate the Ka for chloroacetic acid.