the diluted concentration of HCl = (0.120 M x 25.0 mL) / (25.0 + 40.0) mL = 0.0462 M [H+] = [HCl] = 0.0462 M pH = -log[H+] = -log0.0462 = 1.33 Solution the diluted concentration of HCl = (0.120 M x 25.0 mL) / (25.0 + 40.0) mL = 0.0462 M [H+] = [HCl] = 0.0462 M pH = -log[H+] = -log0.0462 = 1.33.