Question

A lead-acid battery uses a redox reaction in which lead(0) and lead(IV) are both converted to lead(II). This reaction is facilitated by the presence of sulfuric acid, H2SO4, as shown by the reaction

Pb+PbO2+2H2SO4→2PbSO4+2H2O

Suppose that a fully charged lead-acid battery contains 1.50 L of 5.00 M H2SO4. What will be the concentration of H2SO4 in the battery after 3.60 A of current is drawn from the battery for 6.00 hours ?

Answer 1

charge = current x time

             = 3.60 x 6 x 60 x 60 sec

           = 77760 C

moles of electrons utlised = charge / faraday

                                         = 77760 / 96485

                                         = 0.806

moles of H2SO4 = moles of electrons = 0.806

initial moles = 1.5 x 5 = 7.5

moles remains = 7.5 - 0.806 = 6.694

concentration of H2SO4 = moles / volume

                                     = 6.694 / 1.50

                                    = 4.46 M

concentration of H2SO4 = 4.46 M