Question

The [OH-] of an aqueous solution is 3.5 x 10-5. What is the [H+]?

Answer 1

Answer: The concentration of hydrogen ion in the given solution is $2.81 \times 10^{-10}$.

Explanation:

pOH of a solution is the negative logarithm of concentration of hydroxide ions.

Hence, if $[OH^{-}]$ is $3.5 \times 10^{-5}$ then its pOH value is calculated as follows.

$pOH = -log [OH^{-}]\\= -log (3.5 \times 10^{-5})\\= 4.45$

Now, the relation between pH and pOH is as follows.

pH + pOH = 14

pH + 4.45 = 14

pH = 14 - 4.45

= 9.55

And, pH is the negative logarithm of concentration of hydrogen ions. Hence, $[H^{+}]$ is calculated as follows.

$pH = -log [H^{+}]\\9.55 = -log [H^{+}]\\H^{+} = 2.81 \times 10^{-10}$

Thus, we can conclude that the concentration of hydrogen ion in the given solution is $2.81 \times 10^{-10}$.