Weak Acid/Weak Base Hydrolysis

• Is a solution of NH4OCN acidic or basic?

• NH4+ + H2O ? NH3 + H3O+

  Kh = Ka = 1.0 x 10-14/1.76 x 10-5 = 5.7 x 10-10
  

• OCN- + H2O ? HOCN + OH-

  Kh = Kb = 1.0 x 10-14/3.46 x 10- 4 = 2.9 x 10-11
  

• Produces more H3O+ than OH-, so the solution is acidic.

H3O+

OH-

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