Дано:                                                      Решение:

 m(NaNO 3) смеси  = 340 г.          1) Составим уравнение химической реакции  выполним  

                                                           необходимые вычисления и выпишем данные для 

                                                            составления  пропорции:

W ( примеси) -- ?                                   Х г                             33,6 л

                                                                 NaNO 3        =          NaNO 2   +   О 2

                                                                                М = 85 г\ моль                       V M  = 22,4 л

                                                                   m = 170г                                        V     = 22,4 л

Х г NaNO 3  ---------------33,6 л   О 2                     33, 6  х 170

170 г           ------------    22,4 л                Х = ---------------- = 255 г

                                                                              22,4                             m(NaNO 3) чистая  = 255 г.