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

Answer:

The correct answer is A

Explanation:

Answer 2

ANSWER

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.                        

$O=2\times3=6$      

R.H.S

$O=3\times2=6$  

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.                        

$Fe=1\times4=4$      

R.H.S

$Fe=4\times1=4$  

We now, have

L.H.S.                      

Fe= 4                          

O=6                        

R.H.S

Fe =4

O=6

Hence the balanced equation is

$4Fe +3O_2\rightarrow 2Fe_2O_3$