Question

What is the pH of a 0.017 M solution of HCl

Answer 1

pH scale is used to have better appreciation of the value of the hydrogen ion concentration where:

$$\mathrm{pH} = -\log [\mathrm{H}^+]$$

The dissociation equation for HCl is next:

$$\mathrm{HCl} \rightleftharpoons \mathrm{H}^+ + \mathrm{Cl}^-$$

The concentration of $\mathrm{H}^+$ is the same that HCl concentration. This conclusion could be made from upper equation.

$$[\mathrm{H}^+] = [\mathrm{HCl}] = 0.017\ \mathrm{M}$$ $$\mathrm{pH} = -\log [\mathrm{H}^+] = -\log [0.017] = 1.77$$