Answer:
55 moles FeS2
Step-by-step explanation:
You can't do this without knowing what the reactants and products are. Even then the reactants and products have to have equal numbers of atoms on each side of the equation. That's called balancing.
The bare equation is
FeS2 + O2 → Fe2O3 + SO2
It is not balanced. Just as an example, the sulfurs have 2 on the left and 1 on the right. The oxygens have 2 of the left and 5 on the right, so you have to get all of that balanced.
Start with the oxygen in Fe2O3. It's an odd number. Put 2 in front of Fe2O3
FeS2 + O2 → 2Fe2O3 + SO2
But now the Fe's don't balance. Put a 4 in in front of the FeS2
4FeS2 + O2 ===> 2Fe2O3 + SO2
The Ss are way out of kilter. Put an 8 in front of SO2
4FeS2 + O2 → 2Fe2O3 + 8SO2
Finally the oxygens There are 2*3 + 8*2 = 22 oxygens on the right
Put an 11 (because it is O2) on the left
4FeS2 + 11O2 → 2Fe2O3 + 8SO2
That's your balanced equation
4 mols of FeS2 produce 2 moles of Fe2O3
x mols of FeS2 produce 27.5 mols of Fe2O3
4/x = 2/27.5 Cross multiply
2x = 4*27.5
2x = 110 Divide by 2
x = 110/2
x = 55