Fe2O3 + Fe + H2SO4 → FeSO4 + H2O
How would I balance this using oxidation numbers? Is the Fe2 being reduced and the Fe being oxidized?
Yes, Fe in Fe2O3 is going from +6 total to +4 total in 2FeSO4. Fe on the left is going to +2 on the right. The easiest way to do this is to write it in half equations; i.e.,
Fe2O3 ==> 2Fe^2+ and
Fe ==> Fe^2+
and add the spectator ions later.
S
To balance the given chemical equation using oxidation numbers, you need to determine the oxidation numbers of each element and identify any changes in the oxidation state.
Let's assign the oxidation numbers to the elements in the equation:
Fe2O3 + Fe + H2SO4 → FeSO4 + H2O
Fe2O3:
The total charge of Fe2O3 is 0 since oxygen is typically assigned an oxidation number of -2. So, we have:
2x + 3(-2) = 0
2x - 6 = 0
2x = 6
x = +3
Fe:
The oxidation number of Fe is not given, so we will assign it as "Fe."
H2SO4:
Hydrogen (H) is almost always assigned an oxidation number of +1. Oxygen (O) is most commonly assigned an oxidation number of -2. Since the overall charge of H2SO4 is 0, we have:
2(+1) + S + 4(-2) = 0
2 + S - 8 = 0
S = +6
FeSO4:
The overall charge of FeSO4 is 0. Since oxygen is usually -2, we have:
Fe + S + 4(-2) = 0
Fe + S - 8 = 0
Fe + S = +8
H2O:
The overall charge of H2O is 0, and oxygen is typically -2. So we have:
2H + O = 0
2(+1) + O = 0
2 + O = 0
O = -2
Now let's analyze the changes in oxidation state:
Fe2O3:
In Fe2O3, Fe has an oxidation number of +3, while in FeSO4, Fe has an oxidation number of +2. Therefore, Fe is being reduced from Fe2O3 to FeSO4.
Fe:
The oxidation number of Fe is unchanged in the reaction. Therefore, it remains as "Fe."
By comparing the oxidation states, we can conclude that Fe2O3 is being reduced, and Fe remains unchanged. To balance the equation, we need to ensure that the number of electrons lost (oxidation) is equal to the number of electrons gained (reduction).
Fe2O3 + Fe + H2SO4 → FeSO4 + H2O
To balance the equation, we can multiply Fe2O3 by 3, Fe by 8, H2SO4 by 4, and H2O by 6:
3Fe2O3 + 8Fe + 4H2SO4 → 8FeSO4 + 6H2O
The balanced equation using oxidation numbers is:
3Fe2O3 + 8Fe + 4H2SO4 → 8FeSO4 + 6H2O