Question

What mass of iron is contained in 86.6 grams of pyrite, FeS2?

40.3 g

47.3 g

29.2 g

80.6 g

64.1 g

Answer 1

Molar mass of FeS2 = 1*MM(Fe) + 2*MM(S)

= 1*55.85 + 2*32.07

= 119.99 g/mol

mass of FeS2 = 86.6 g

we have below equation to be used:

number of mol of FeS2,

n = mass of FeS2/molar mass of FeS2

=(86.6 g)/(119.99 g/mol)

= 0.7217 mol

This is number of moles of FeS2

one mole of FeS2 contains 1 moles of Fe

we have below equation to be used:

number of moles of Fe = 1 * number of moles of FeS2

= 1 * 0.7217

= 0.7217

Molar mass of Fe = 55.85 g/mol

we have below equation to be used:

mass of Fe,

m = number of mol * molar mass

= 0.7217 mol * 55.85 g/mol

= 40.3 g

Answer: 40.3 g