Question

A sample of 4.5 mg of an unknown monohydric alcohol, R–OH was added to methylmagnesium iodide. A gas is evolved and is collected and its volume measured to be 3.1 mL. The molecular weight of the unknown alcohol is___ g/mol. [Nearest integer]

Answer 1

ROH+CH3MgI$\rightarrow$ROMgI+CH4(g)
moles of CH4 = moles of ROH
⇒ $\frac{V^2}{2400}$=$\frac{m}{M.M}$ (Assuming NTP Condition )
⇒$\frac{3.1}{22400}$=$\frac{4.5×10^{−3}}{M⋅M}$
⇒MM=32.51
Nearest Integer = 33