A solution of hydrochloric acid has a pH of 3. What is the approximate new pH if diluted ten times?

💡 Explanation:

A pH of 3 corresponds to a hydrogen ion concentration $([H^+]$) of $10^{-3} M$. Diluting the solution ten times reduces the concentration by a factor of 10. The new $[H^+]$ is $frac{10^{-3}}{10} = 10^{-4} M$. The new pH is calculated as $-log_{10}[H^+]$, which is $-log_{10}(10^{-4}) = 4$.