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

Explanation

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)`.