Determination of the molecular formula of alcohols

Exercise 3

    

$ 6.40\; g $ of alcohol are vaporized and occupy at $100^ oC$ and $1.00\; atm$ a volume of $6.19 \; L$ 1) Determine the molar mass! 2) What alcohol is it?

1) Gas law: $n$ $=$ $\frac{PV}{RT}$ $n$ $=$ $\frac{1.00\cdot6.19}{0.083\cdot 273.15}$ $n$ $=$ $0.200$ Molar mass: $M$ $=$ $\frac{m}{n}$ $M$ $=$ $\frac{6.40}{0.200}$ $M$ $=$ $32.0 \frac{g}{mol}$ 2) The formula has the type: $ROH$(more than one alcohol function is impossible) $M_R$ $=$ $32.0$ $-$ $16.0$ $-$ $1.0$ $=$ $15.0$ $R$ $=$ $CH_3$ It is methanol !