Question

Write the equation for the reaction that occurs when acetic acid is combined with sodium hydorixide. For a 1M solution of acetic acid, calculate the pH of the resulting solution when 0.25, 0.5, and 0.75 molar equivalents of NaOH are added.

Answer 1

CH3COOH(aq) + NaOH(aq) ---> CH3COONa(aq) + H2O(l)

   1 mol CH3COOH = 1 mol NaOH

after addition of naOH

pH = pka + log(base/acid-base)

pka of ch3cooh = 4.745

1) 0.25 molar equivalents of NaOH are added.

   pH = 4.745+log(0.25/(1-0.25))

      = 4.27

2) 0.5 molar equivalents of NaOH are added.

   pH = 4.745+log(0.5/(1-0.5))

      = 4.745

3) 0.75 molar equivalents of NaOH are added.

   pH = 4.745+log(0.75/(1-0.75))

      = 5.22