50 г                                              Х г

   H2SO4       +        2NaOH      =    Na2SO4     +     2H2O

n = 1 моль                                     n = 1 моль

Mr = 98 г/моль                              Mr = 142 г/моль

m = 98 г                                        m = 142 г

50 г H2SO4     -     Х г Na2SO4

98 г H2SO4    -     142 г Na2SO4

m(Na2SO4) = 50 * 142 / 98 = 72 г