Question

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Iron(III) oxide is formed when iron combines with oxygen in the air. How many grams of Fe2O3 are formed when 20.5 of Fe reacts completely with oxygen? 4Fe(s) +3O2(g) → 2Fe2O3(s)

Answer 1

From the balanced equation:
4mol Fe will produce 2mol Fe2O3
Molar mass Fe = 55.847g/mol
16.7gFe = 16.7/55.847 = 0.3mol Fe
This will produce 0.15mol Fe2O3
Molar mass Fe2O3 = 159.6887 g/mol
0.15mol = 159.6887*0.15 = 23.95g Fe2O3 produced
Hope this helps