The concentration of hydrochloric acid in a given solution is 1.0-8 M. What is the value of pH for this solution?

The pH of a 1.0 × 10⁻⁸ M hydrochloric acid (HCl) solution is less than 7. While a simple calculation using -log[H⁺] might suggest a pH of 8, this is incorrect because HCl is an acid and cannot produce a basic solution . In extremely dilute solutions, the contribution of hydronium ions (H⁺) from the autoionization of water (1.0 × 10⁻⁷ M) becomes significant and must be accounted for alongside the H⁺ from the acid . By solving the equilibrium equation [H⁺]total = [H⁺]acid + [H⁺]water, where [H⁺][OH⁻] = 10⁻¹⁴, the total [H⁺] is found to be approximately 1.1 × 10⁻⁷ M . This results in a pH of approximately 6.96 . Since 6.96 is less than 7, the solution remains acidic, consistent with the properties of a strong acid in water .