thx

a) Determine the change in e.m. f., when we add to the cell a 0.2mol/kg solution of KF. (Consider that all electrolytes are fully dissociated and do not form ionic pairs.) in Pt(s)H2g)(1atm),HCl(m),AgCl(s)Ag(s),t=25.0C. The e.m.f. of this battery has been measured at several molalities: b) This time at 298K and with an activity for the solute aHCl=at=0.24. Using the tabulated standard potentials for the half-cells, determine the pressure of H2 needed to produce an electromotive force of 0.30V. (Consider the gas as ideal.)