Â
CH3COOH + H2O -----------> CH3COO- + H3O+
    Â
IÂ Â Â Â Â Â Â Â Â
0.14MÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0
    Â
CÂ Â Â Â Â Â Â Â Â
-x                                           Â
+x              Â
+x
    Â
EÂ Â Â Â Â Â Â Â
0.14-x                                     Â
+x                Â
+x
                             Â
Ka = [CH3COO-][H3O+]/[CH3COOH]
                            Â
1.8*10-5Â Â = x*x/0.14-x
                            Â
1.8*10-5 *(0.14-x) = x2
                                  Â
x  = 0.00157M
                    Â
[H3O+]  = x  = 0.00157M
                    Â
PHÂ Â Â = -log[H3O+]
                             Â
= -log0.00157
                             Â
= 2.8041