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Determination of the molecular formula by the percentage of elements and the molar mass

Exercise 1

A substance has a molar mass of $M=46\frac{g}{mol}$. It contains $52.2\% \; C$. $34.8\% \; O$ and $13.0\% \; H$. Find its molecular formula.

One mole of the substance contains: $0.522\cdot 46=24.0\; g \; C$ = $\frac{24.0}{12.0}= 2\; mol C$ $0.348\cdot 46=16.0\; g \; O$ = $\frac{16.0}{16.0} = 1\; mol O$ $0.130\cdot 46=6.0\; g \; H$ = $\frac{6.0}{1.0} = 6\; mol H$ Molecular formula: $C_2H_6O$