350 г                                               Х г

 H2SO4       +       2NaOH       =      Na2SO4       +     2H2O

n = 1 моль                                   n = 1 моль

М= 98 г/моль                              М= 142 г/моль

m = 98 г                                      m = 142 г

350 г H2SO4    -   Х г Na2SO4

98 г H2SO4    -   142 г Na2SO4

m(Na2SO4) = 350 * 142 / 98 = 507 г