How would you balance the following equation: Fe+O2 --> Fe2O3?

1 Answer
Nov 2, 2015

Answer:

#4Fe# + #3O_2# #rarr# #2Fe_2O_3#

Explanation:

Step 1: Tally the number of atoms based on subscript.

#Fe# + #O_2# #rarr# #Fe_2O_3# (unbalanced)

left side: Fe = 1; O = 2
right side: Fe = 2; O = 3

Step 2: Start balancing the simple molecules first, in this case the #O_2#

#Fe# + #color (green) 3O_2# #rarr# #Fe_2O_3#

left side: Fe = 1; O = 2 x #color (green) 3# = 6
right side: Fe = 2; O = 3

Since there are now 6 #O# atoms on the left, there must also be 6 #O# atoms on the right. Notice that the right hand is one big molecule so whatever coefficient you would use to balance the #O# atoms, you would also need to apply to the bonded #Fe# atom.

#Fe# + #3O_2# #rarr# #color (red) 2Fe_2O_3#

left side: Fe = 1; O = 2 x 3 = 6
right side: Fe = 2 x #color (red) 2# = 4; O = 3 x #color (red) 2# = 6

Step 3: Now balance the rest of the equation.

#color (blue) 4Fe# + #3O_2# #rarr# #2Fe_2O_3#

left side: Fe = 1 x #color (blue) 4# = 4; O = 2 x 3 = 6
right side: Fe = 2 x 2 = 4; O = 3 x 2 = 6

The equation is now balanced.