Question

Iron metal reacts with elemental oxygen to form rust according to the unbalanced reaction, Fe(s) + O2(g) → Fe2O3(s),. What is the coefficient of the oxygen, O2(g), in the balanced reaction?

a
1
b
2
c
3
d
4

Answer 1

c. 3

Step-by-step explanation:

The unbalanced reaction expression is given as:

Fe + O₂ → Fe₂O₃

To balance the expression gives the coefficient of oxygen.

Assign the coefficients a,b, c and use a mathematical approach to solve this problem:

aFe + bO₂ → cFe₂O₃

Conserving Fe: a = 2c

O: 2b = 3c

Now let c = 1, a = 2, b =
`(3)/(2)`

Multiply through by 2,

a = 4, b = 3 and c = 2

4Fe + 3O₂ → 2Fe₂O₃

The coefficient of O₂ is 3