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

The correct answer is A

EXPLANATION

From the equation

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.                        

R.H.S

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

R.H.S

We now, have

L.H.S.                      

Fe= 4                          

O=6                        

R.H.S

Fe =4

O=6

Hence the balanced equation is

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