A sample of 4 . 5 mg of an unknown monohydric alcohol, R - OH was added to methylmagnesium iodide. A gas is…

Alcohols on reaction with Grignard reagent forms hydrocarbons.This is due to the presence of active hydrogen in alcohols and here grignard reagent acts as a base.

When any alcohol is treated with methyl magnemsium iodide the hydrocarbon formed should be methane gas.

$\mathrm{ROH}+{\mathrm{CH}}_3\mathrm{MgI}\to \mathrm{ROMgI}+{\mathrm{CH}}_4\left(\mathrm{g}\right)$

Number of moles of ${\mathrm{CH}}_4=$ Number of moles of $\mathrm{ROH}$

$\Rightarrow \frac{\mathrm{Volume}\left(\mathrm{Litres}\right) \mathrm{of} \mathrm{the} \mathrm{gas}}{22400}=\frac{\mathrm{mass} \mathrm{of} \mathrm{the} \mathrm{gas}}{\mathrm{Molecular} \mathrm{mass} \mathrm{of} \mathrm{the} \mathrm{gas}}$ (Assuming $\mathrm{NTP}$ Condition)

$\Rightarrow \frac{3.1}{22400}=\frac{4.5\times {10}^{-3}}{\mathrm{Molecular} \mathrm{mass} \mathrm{of} \mathrm{the} \mathrm{gas}}$

$\Rightarrow \mathrm{MM}=32.51$

$=33$$\mathrm{g}/\mathrm{mol}$