Question

What is the empirical formula of a compound containing 36.5% sulfur and 63.5% iron?

• A. FeS
• B. $F{e}_{63}{S}_{36}$
• C. $F{e}_{2}S$
• D. $F{e}_2{S}_2$
• E. 2FeS

Answer 1

The correct option is A FeS

100 g of the compound will contain $36.5gSand63.5gFe.$
The atomic masses of $S$ and $Fe$ are 32.1 g/mol and 55.8 g/mol respectively.
The number of moles are obtained by dividing mass with molar mass.
The number of moles of S $=\frac{36.5}{32.1}=1.137$ moles

The number of moles of Fe $=\frac{63.5}{55.8}=1.137$
Hence, the ratio of the number of moles of Fe to the number of moles of S is $1.137:1.137=1:1.$
The empirical formula of the compound is $FeS.$