The Pka of acetic acid is 4.76. calculate the PH if a solution of acetic acid is

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Chemical reaction CH3COOH + NaOH -----> CH3COONa + H2O Initial                   56 moles       44moles            0 Change                -44 moles    -44moles            + 44 moles Final (mol)        (56-44) mol      0                       44 moles At this stage we have a buffer system made up of CH3COOH andCH3COO- ( from the salt , CH3COONa). To calculate the pH of thesolution, we write                   Ka = [H+][CH3COO-]/[CH3COOH]                  [H+] = (Ka)(CH3COOH)/[CH3COO-]                           = ( 1.73*10^-5)(12)/(44)                           = 0.472*10^-5     therefore pH = -log(0.472*10^-5)                        = 5-log(0.472)                         = 4.67 given data pka = -logKa                   4.76 = -logKa               Ka = 1.73*10^-5

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