Concentration of HCN and NaCN in a solution is 0.01M each.Calculate [H30+]& [OH-].Ka(HCN)=0.00000000072

(i)  HCN    H⁺   +   CN^-

(0.01 - X)M           XM         XM

(ii) NaCN   Na⁺ + CN^-

Initial  0.01 M  0M  0M

Final   0.0M  0.01M  0.01M

So at equilibrium, [H⁺] = XM

[CN^-]_Total  =  [CN^-]_Acid  +  [CN^-]_Salt

= XM  +  0.01M  = 1.01M

[HCN] = 0.01M – XM = 0.01M

 

 

= -log[H⁺]  = log 7.2 X 10^-10