5,4 г                                                 Х г

    2Al             +          3Br2        =      2AlBr3

n = 2 моль                                      n = 2 моль

Mr = 27 г/моль                               Mr = 267 г/моль

m = 54 г                                          m = 534 г

5,4 г Al    -    Х г AlBr3

54 г Al     -   534 г AlBr3

m(AlBr3) = 5,4 * 534 / 54 = 53,4 г