Answer to Question #125395 in Organic Chemistry for Orlando Kwame nyavi maxwell

Question

).Given a 0.1M aqueous solution each of NH4Cl and CH3COONa (ammonium ethanoate),state and explain which of them you would expect to have a lower pH

Answer 1

NH₄Cl is the salt of strong acid (HCl) and weak base (NH₄OH)

pH of NH₄Cl is = 7-1/2pK_b – 1/2logC      [ pK_b of NH₄OH= 4.75, C= 0.1 M]

                        = 7- (4.75/2) -1/2log0.1

                      = 5.162

CH₃COONa is the salt of weak acid (CH₃COOH) and strong base (NaOH)

pH of CH₃COONa  is = 7+ 1/2pK_a + 1/2logC      [ pK_a of CH₃COOH = 4.76, C= 0.1 M]

                        = 7+(4.76/2) +1/2log0.1

                      = 8.88

ammonium ethanoate is the salt of weak acid (CH₃COOH) and weak base (NH₄OH)

pH of ammonium ethanoate is = 7+1/2pK_a – 1/2pK_b

                                               = 7+(4.76/2) - (4.75/2)

                                                 = 7.005

NH₄Cl is the lower pH (Answer)