# . The mineral manganosite is a compound of manganese-55 and oxygen-16. If 77% of the mass of manganosite is due to manganese, what is the empirical formula of manganosite?

Nov 5, 2016

$\text{Manganosite}$ has an empirical formula of $M n O$

#### Explanation:

Typically with these problems, we assume a mass of $100 \cdot g$ of compound, and we work out the empirical formula on this basis.

${\text{Moles of " }}^{55} M n$ $=$ $\frac{77.0 \cdot g}{55.0 \cdot g \cdot m o {l}^{-} 1}$ $=$ $1.40 \cdot m o l .$

${\text{Moles of " }}^{16} O$ $=$ $\frac{23.0 \cdot g}{16.0 \cdot g \cdot m o {l}^{-} 1}$ $=$ $1.44 \cdot m o l .$

These are tolerably close to equimolar quantities, and thus the empirical formula is $M n O$.