A cell using a potassium ISE based on a liquid membrane using valinomycin as an ionophore and a silver/silver chloride electrode gives a voltage of \(-0.273 \mathrm{~V}\) in a solution of \(7.50 \times 10^{-6} \mathrm{M} \mathrm{KCl}\) standard solution (using an ionic strength buffer). Assuming that the electrode responds ideally, calculate the cell potential for the same conditions plus the presence of \(2.00 \times 10^{-2} \mathrm{M} \mathrm{HCl}\) as an interfering electrolyte.