Since hydrochloric acid HCl is a strong acid, it will completely dissociate in water. This means that the concentration of hydrogen ions H+ will be equal to the initial concentration of HCl.[H+] = 0.1 MTo calculate the pH, we use the formula:pH = -log10[H+]pH = -log10 0.1 pH = - -1 pH = 1So, the pH of a 0.1 M solution of hydrochloric acid is 1.