Question

Calculate the $pH$ of a solution at ${25}^{0}C$ that contains ${10}^{-10}M$ of hydronium ions.

• A. 1
• B. 7
• C. 4
• D. 10

Answer 1

The correct option is D 10

The pH is calculated by taking the negative log of the concentration of hydrogen ions.

However hydrogen ions combine with water (in aqueous medium) to form hydronium ions which are more stable and comparatively less energetic than the hydrogen ions.

$pH=-lo{g}_{10}\left[H_3{O}^{+}\right]$

Here, the concentration of hydronium ions is $\left[H_3{O}^{+}\right]={10}^{-10}M$

$\therefore pH=-lo{g}_{10}\left({10}^{-10}\right)$

$\therefore pH=10$