What is the pH of a 2.5 x 10−3 M HCl solution?

The pH of a solution is calculated using the formula:

pH = -log[H+]

Where [H+] is the concentration of hydrogen ions in the solution.

In the case of HCl, it is a strong acid and it dissociates completely in water to form H+ and Cl- ions. Therefore, the concentration of H+ ions is equal to the concentration of HCl.

So, [H+] = 2.5 x 10^-3 M

Substituting this into the formula:

pH = -log(2.5 x 10^-3)

Using a calculator to find the log:

pH = -(-2.60)

Therefore, the pH of the solution is approximately 2.60.