Answer:
pH = 2.38
Explanation:
Recall that HCl is a strong acid and hence dissociates completely into H⁺ and Cl⁻ ions. Thus, the solution's H⁺ concentration is equivalent to the acid concentration. That is, [H⁺] = 4.2 × 10⁻³ M.
Therefore, the pH of the solution is:
[tex]\displaystyle \begin{aligned}\text{pH} & = -\log[\text{H}^+] \\ \\ & = -\log (4.2\times 10^{-3}) \\ \\ & = 2.38\end{aligned}[/tex]
