Question

What are the equilibrium concentrations of all the solute species in a 0.95 M solution of hydrogen cyanide, HCN? The Ka value = 6.2 x 10^-10.

(a) [H3O+], M;
(b) [OH-], M;
(c) [HCN], M;
(d) What is the pH of the solution? For HCN

So far i have calculated the concentration of H30+ = 2.4x10^-5
however, i am unsure of how to calculate the OH- concentration. Do i just assume that it is the same concentration as H30+? Or is there an equation i have to use.

Kind regards

Answer 1

You know (H3O^+)(OH^-) = Kw = 1E-14 and with your value of (H3O^+) that will let you calculate (OH^-).