Question

Determine the [OH−] in a 0.22 M solution of HClO4. Answer in units of M.?

Answer 1

Consider the equilibrium of this acid's dissociation,

`HClO_4 rightleftharpoons H^(+) + ClO_4^-`

Moreover, let's assume that `HClO_4` is a strong acid and will fully dissociate.

Hence,

`[H^+]_"eq" = 0.22"M"`

Now, recall,

`K_"w" = [H^+][OH^-] = 1.0*10^-14`

Hence,

`=> [OH^-] = K_"w"/[H^+]_"eq" approx 4.5*10^-14"M"`

Yes, even in a solution of strong acid, there are still hydroxide ions!