Question

What is the sum of the coefficients when the following equation is balanced with the simplest whole numbers? If a substance has an understood 1 as the coefficient, do not forget to add it in. Fe2O3 (s) + C (s) → Fe (s) + CO2 (g)

Answer 1

`12`

Explanation:

`Fe_2O_3 (s)+C (s)rarrFe (s)+CO_2 (g)`

Number of iron (Fe) atoms: 2 on the LHS, 1 on the RHS.
Number of carbon (C) atoms: 1 on the LHS, 1 on the RHS.
Number of oxygen (O) atoms: 3 on the LHS, 2 on the RHS.

Since we have an odd number of oxygens, we should probably balance that first.

Multiply by `2`: `2Fe_2O_3 (s)+C (s)rarrFe (s)+CO_2 (g)`

Let's balance the oxygen on the other side by multiplying by `3`: `2Fe_2O_3 (s)+C (s)rarrFe (s)+3CO_2 (g)`

Balance the carbon by multiplying by `3` on the LHS: `2Fe_2O_3 (s)+3C (s)rarrFe (s)+3CO_2 (g)`

Finally, balance the iron by multiplying by `4` on the LHS: `2Fe_2O_3 (s)+3C (s)rarr4Fe (s)+3CO_2 (g)`

This is our balanced equation in its simplest form.

The sum of the coefficients is `2+3+4+3=12`.