Question

Calculate the number of moles of methyl alcohol in 2 molal solution in 5 L. The density of solution is 0.981 $kg.d{m}^{-3}$. Given that, molar mass of methyl alcohol is 32 g.$mo{l}^{-1}$ .

Answer 1

Given,

$m=2$

$V=5d{m}^3$

$\rho =0.981kg/d{m}^3=0.981g/ml$

$M=32g/mol$

Since $m=\frac{1000M}{\rho \times 1000-M_b\times M}$

Since $2=\frac{1000M}{0.981\times 1000-32\times M}$

Hence, $M=1.844mol/d{m}^3$

Number of moles of methyl alcohol $=M\times V=1.842\times 5=9.22moles$