3Fe+3Br2→3FeBr2 (i) 3FeBr2+Br2→Fe3Br8 (ii)
Fe3Br8+4Na2CO3→8NaBr+4CO2+Fe3O4 (iii)
Mol of Fe = 1 mol (given)
In reaction (i), 3 mol of Fe produce 3 mol of FeBr2.
hence, 1 mol will produce 1 mol of FeBr2.
In (ii) reaction, 3 mol of FeBr2 produces 1 mol of Fe3Br8.
So, 1 mol will produce 0.33 mol.
In (iii) reaction, 1 mol of Fe3Br8 produces 8 mol of NaBr.
So, 0.33 mol produce = 8 × 0.33 = 2.64 mol of NaBr.
Amount of NaBr in grams = 2.64 mol × 103 g/mol = 271.92 g