Chapter 15, Problem 15.125QP

In the vapor phase, acetic acid molecules associate to a certain extent to form dimers:

$2{\text{CH}}_3\text{COOH}(g)\stackrel{}{\rightleftharpoons }{({\text{CH}}_3\text{COOH})}_2(g)$

At 51°C the pressure of a certain acetic acid vapor system is 0.0342 atm in a 360-mL flask. The vapor is condensed and neutralized with 13.8 mL of 0.0568 M NaOH. (a) Calculate the degree of dissociation (α) of the dimer under these conditions:

${{\text{(CH}}_3\text{COOH)}}_{\text{2}}\stackrel{}{\rightleftharpoons }{\text{2CH}}_3\text{COOH}$

(Hint: See Problem 14.117 for general procedure.) (b) Calculate the equilibrium constant KP for the reaction in (a).