Question

Iron reacts with atmospheric oxygen to form iron oxide or ferric oxide. Look at the chemical equation for this reaction: Fe + O2 → Fe2O3

This equation is unbalanced. Which of the following is the correct balanced equation for this reaction?

A. 4Fe + 3O2 → 2Fe2O3
B. 3Fe + 4O2 → 2Fe2O3
C. 2Fe + 4O2 → 3Fe2O3
D. 3Fe + 3O2 → 4Fe2O3
E. 4Fe + 4O2 → 3Fe2O3

Answer 1

The correct answer is A

Step-by-step explanation:

Answer 2

The correct answer is A

EXPLANATION

From the equation
`Fe + O_2 \rightarrow Fe_2O_3`

L.H.S.

Fe = 1

O =2

R.H.S

Fe =2

O =3

Now, let try to balance the oxygen atoms first,

To do this, we know the Least Common Multiples of 2 and 3 is 6

To get 6 atoms of oxygen at L.H.S multiply 2 by 3 and on the R.H.S, multiply 3 by 2

L.H.S.

`O=2*3=6`

R.H.S

`O=3*2=6`

This means that, 3 should be in front of
`O_2` at the L.H.S and 2 should come before
`Fe_2O_3` in the R.H.S of the equation

Now, we have

L.H.S.

Fe = 1

O = 6

R.H.S

Fe =4

O =6

The equation is still not balanced since Fe is not balance

The Least Common Multiple of 1 and 4 is 4

Which means that we need to multiply 1 by 4 at the L.H.S and 4 by 1 at the R.H.S

L.H.S.

`Fe=1*4=4`

R.H.S

`Fe=4*1=4`

We now, have

L.H.S.

Fe= 4

O=6

R.H.S

Fe =4

O=6

Hence the balanced equation is

`4Fe +3O_2\rightarrow 2Fe_2O_3`