Syre-base ligevægt

a)
                      CH₃COOH _(aq)   +   H₂O _(l)   <--->   CH₃COO^- _(aq)   +   H₃O⁺ _{(aq)
     molariteter:}      c_s - α·c_s                                            α·c_s                            α·c_{s           0 < α < 1 hvor α er hydronolysegraden}

b)
                       [H₃O⁺] = 10^-pH = 10^-3,01 ≈ 0,001 M
                           
                              [H₃O⁺]      0,001 M
                       α = ---------- = ------------- = 0,0014 = 0,14%
                                 c_s          0,700 M

c)
       ligevægtsbrøken
       giver:

                                       [CH₃COO^-] • [H₃O⁺]
                                      ---------------------------- = K_{s            Ks er temperaturafhængig}
                                             [CH₃COOH]


                                           [H₃O⁺]²
                                      ----------------- = K_s               som ved indsættelse af  [H₃O⁺] = 0,001 M giver
                                        c_s - [H₃O⁺]

                                                  (0,001 M)²
                                      ------------------------------- = K_s =  1,431·10^-6 M            
                                        (0,700 M) - (0,001 M)
 

                                      pK_s = -log(K_s) = -log(1,431·10^-6) = 5,84

       ethansyres officielle pK_s-værdi ved 25ºC er 4,75

d)
      I det følgende regnes videre med ethansyres
      officielle pK_s-værdi ved 25ºC   4,75:

      pK_b(CH₃COO^-) = 14 - 4,75 = 9,25     dvs en svag base

      I 0,600 M CH₃COONa-opløsning
      er
                          pOH = (1/2)•(pK_b - log(c_b)) = (1/2)•(9,25 - log(0,600)) = 4,74
                          pH = 14 - pOH = 14 - 4,74 = 9,26

e)

      100 mL 0,200 M CH₃COOH titreret med 100 mL 0,200 M NaOH giver
      200 mL 0,1 M CH₃COONa

                     pOH = (1/2)•(pK_b - log(c_b)) = (1/2)•(9,25 - log(0,100)) = 5,13
                     pH = 14 - pOH = 14 - 5,13 = 8,87