Question

Determine the molecular formula of an oxide of iron in which the mass percent of iron and oxygen are `69.9` and `30.1`, respectively.

Answer 1

For calculation of empirical formula,
Empirical formula mass of `Fe_(2)O_(3)`
`=2xx55.85+3xx16.00=159.7 g mol^(-1)`
`n=("Molar mass")/("Empirical fomula mass")=159.8/159.7=1`
Hemce, molecular formula is same as empirical formula viz., `Fe_(2)O_(3)`.