Question

How many moles of iron metal are required to react completely with 12 moles of oxygen?

Answer 1

9.0 moles of O2 and produce 6.0 moles of Fe2O3

Step-by-step explanation:

Fe→Fe3++3e− iron. Is oxidised: it's losing electrons

O2+4e−→2O2− oxygen Is reduced, it's gaining electrons

Balance for the electrons.

The smallest common product of 3 and 4 Is 12.

So we get:

4Fe→4Fe3++12e−

3O2+12e−→6O2−

Adding:

4Fe+3O2+12e−→4Fe3++12e−+6O2−

The electrons balance so they cancel out:

4Fe+3O2→4Fe3++6O2−

Since Fe and O can combine in a ratio of 2:3

4Fe+3O2→4Fe3++6O2−→2Fe2O3

Extra :

Pure iron. won't rust, because the oxide layer would form a protective skin (as aluminium does). It needs some impurities (mainly carbon) and, apart from the oxygen, some moisture -- even carbondioxide 'helps'. In that case iron.-hydroxy-oxides and -carbonates are formed, and these flake, no longer protecting the iron. underneath.

Answer 2

16 moles

Step-by-step explanation:

from the equation:

4Fe + 3O2 -----> Fe2O3

the mole ratio of Fe to O2 follows,

3 moles O2 reacts with 4 moles Fe.

therefore,

1 mole O2 reacts with 4/3 moles Fe

and 12 moles O2 reacts with (4/3) × 12 moles Fe = 16 moles