Question

In a reaction, 3.78g of iron metal is reacted completely with excess sulfur to produce only one product, a compound that weighs 5.95g. What is the empirical formula of this compound

Answer 1

Answer: The empirical formula is
`FeS`

Step-by-step explanation:

Mass of Fe = 3.78 g

Mass of S = (5.95-3.78) g = 2.17 g

Step 1 : convert given masses into moles.

Moles of Fe =
`\frac{\text{ given mass of Fe}}{\text{ molar mass of Fe}}= (3.78g)/(56g/mole)=0.0675moles`

Moles of S =
`\frac{\text{ given mass of S}}{\text{ molar mass of S}}= (2.17g)/(32g/mole)=0.0678moles`

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For Fe =
`(0.0675)/(0.0675)=1`

For S =
`(0.0678)/(0.0675)=1`

The ratio of Fe : S= 1: 1

Hence the empirical formula is
`FeS`