Browse Questions

The expression relating molarity (M) and molality (m) of a solution is (where $\rho$ is the density of solution and $M_2$ is the molar mass of solute)

$\begin{array}{1 1}m=\large\frac{M}{\rho+MM_2}\\m=\large\frac{M}{\rho-MM_2}\\m=\large\frac{\rho+MM_2}{M}\\m=\large\frac{\rho-MM_2}{M_2}\end{array}$

Answer : $m=\large\frac{M}{\rho-MM_2}$
$m=\large\frac{n_2}{m_1}=\frac{n_2}{m_{total}-m_2}=\frac{n_2}{m_{total}-(m_2/M_2)M_2}$
$\Rightarrow \large\frac{n_2}{\rho V-n_2M_2}=\frac{n_2/V}{\rho-(n_2/V)M_2}=\frac{M}{\rho-MM_2}$