Question:
The concentration of hydrogen ion in a sample of soft drink is $3.8 \times 10^{-3} \mathrm{M}$. what is its $\mathrm{pH}$ ?
Solution:
Given,
$\left[\mathrm{H}^{+}\right]=3.8 \times 10^{-3} \mathrm{M}$
pH value of soft drink
$=-\log \left[\mathrm{H}^{+}\right]$
$=-\log \left(3.8 \times 10^{-3}\right)$
$=-\log 3.8-\log 10^{-3}$
$=-\log 3.8+3$
$=-0.58+3$
$=2.42$