The elementary analysis of alcohols by combustion

Exercise 3

The complete combustion of $0.37\;g$ of a saturated aliphatic mono-alcohol requires a volume of oxygen $V = 0.672\;L$ STP 1) Write the complete combustion equation of such an alcohol! 2) Find the mass of carbon in A! 3) Find the molecular formula of A!

1) $C_nH_{2n+2}O $ $+$ $\frac{3n}{2}\;O_2$ $\rightarrow$ $ n\;CO_2$ $ +$ $ (n+1)\;H_2O$ 2) $n_{O_2}$ $=$ $\frac{0.672}{22.4}$ $=$ $0.030 \; mol$ $\frac{3n}{2} \; mol \;O_2$ consume $n\; mol\; C$ $\frac{3}{2} \; mol \;O_2$ consume $1\; mol \;C$ $0.030 \; mol \;O_2$ consume $0.020\; mol\; C$ $m_C$ $=$ $0.020\cdot 12$ $ $ $ 0.24 \; g$ 3) Percentage of carbon: $\frac{0.24\cdot 100}{0.37}$ $=$ $\frac{12n\cdot 100}{12n +2n+2+16}$ $n$ $=$ $4$ Molecular formula: $C_4H_{10}O$