At an applied discharge potential, if the volumes of  ${\mathrm{O}}_2\mathrm{and}{\mathrm{Cl}}_2$  liberated by the electrolysis of 1 liter of an aqueous  $\text{NaCl}$  solution are in the 2 : 1, after consumption of 4.825 coulombs of charge, the pH of the solution is ……