Question

Calculate the [H3O+] and [OH-] for 0.0084 M H2SO4 Answer in units of M for both answers.

Answer 1

You can realize that sulfuric acid (H2SO4) is a strong acid because it can dissociate completely in an aqueous solution, so we can assume that the concentration [H3O+] is 0.0084 M.

We can find [OH-], using the following formula:

$\lbrack H_3O^+\rbrack\lbrack OH^-\rbrack=10^{-14}.$

So, let's clear [OH-] and replace the data that we have:

$\begin{gathered} \lbrack OH^-\rbrack=\frac{10^{-14}}{\lbrack H_3O^+\rbrack}, \\ \lbrack OH^-\rbrack=\frac{10^{-14}}{0.0084}, \\ \lbrack OH^-\rbrack=1.190\cdot10^{-12}M\approx1.2\cdot10^{-12}M. \end{gathered}$

The answer is that we have 0.0084 M of [H3O+] and 1.2 x 10^(-12) M of [OH-].