What mass of iron is needed to react with sulfur in order to produce 96 g of iron (III) sulfide

Answer 1

First, we must write a correctly balanced equation for the reaction taking place:

2Fe(s) + 3S(s) ==> Fe₂S₃

Next, using molar masses of Fe and Fe₂S₃, along with the balanced equation, we can determine moles of Fe needed, and then finally, convert that to mass of Fe needed.

atomic mass Fe = 55.9 g / mol

molar mass Fe₂S₃ = 208 g / mol

moles of Fe₂S₃ in 96 g = 96 g x 1 mol / 208 g = 0.462 mols Fe₂S₃

moles Fe needed = 0.462 mols Fe₂S₃ x 2 mol Fe / mol Fe2S3 = 0.924 mols Fe

mass Fe needed = 0.924 mols Fe x 55.9 g / mol = 52 g Fe needed (2 sig. figs.)