86 г                                                          Х г

   2Na            +           2H2O       ->         2NaOH       +       H2

n = 2 моль                                             n = 2 моль

Mr = 23 г/моль                                     Mr = 40 г/моль

m = 46 г                                                 m = 80 г

86 г Na     -     Х г NaOH

46 г Na     -    80 г NaOH

m(NaOH) = 86 * 80 / 46 = 149 г