# What mass of iron is needed to react with 16.0 grams of sulfur? 8 Fe + S8 ---> 8 FeS

May 14, 2014

How many grams of Fe are produced if 16.0 grams of sulfur?

We begin with a balanced chemical equation that is provided in the question.

$8 F e + {S}_{8} \to 8 F e S$

Next we determine what we have and what we want.
We have 16.0 grams of sulfur and we want grams of iron.

We set up a roadmap to solve the problem

$g r a m s S \to m o l S \to m o l F e \to g r a m s F e$

We need the molar mass ($g f m$) of $S$ and $F e$.
$S$ = 32.0 g/mol and $F e$ = 55.8 g/mol.

We need the mole ratio between $S$:$F e$ 1:8. This comes from the coefficients of the balanced chemical equation.

Now we set up conversion factors following the roadmap from above.
Unit we want in the numerator, unit to cancel in the denominator.

$16.0 g S \cdot \frac{1 m o l S}{32.0 g S} \cdot \frac{8 m o l F e}{1 m o l S} \cdot \frac{55.8 g F e}{1 m o l F e} =$

Multiply the numerators, and divide the denominators.

The outcome is
$223.2 g F e$
will be consumed with 16.0 grams $S$