Hydrochloric acid HCl is a strong acid, which means it completely dissociates in water into hydrogen ions H+ and chloride ions Cl- . The concentration of hydrogen ions in the solution is equal to the concentration of the HCl.In this case, the concentration of HCl is 0.05 M, so the concentration of H+ ions is also 0.05 M.To calculate the pH of the solution, use the pH formula:pH = -log10[H+]where [H+] is the concentration of hydrogen ions in moles per liter M .pH = -log10 0.05 pH 1.3The pH of the solution containing 0.05 M hydrochloric acid is approximately 1.3.