Question

Calculate the molality of 58.5 g of NaCl (Molar mass of NaCl= 58.5 $gmo{l}^{-1})$ dissolved in 500 g of water.

• A. 1 m
• B. 2 m
• C. 0.5 m
• D. 1.5 m

Answer 1

The correct option is B 2 m

Molality is given by,
Molality (m)= $\frac{n_{solute}}{W_{solvent}\left(g\right)}\times 1000$
Where, $n_{solute}$ is the number of moles of solute and $W_{solvent}$ is the weight of solvent.
$Molality\left(m\right)=\frac{W_{solute}\times 1000}{M_{solute}\times W_{solvent}}$
Where, $M_{solute}$ is the molar mass of the solute.
Molality (m)= $\frac{58.5\times 1000}{58.5\times 500}$=2
Therefore, the molality of the given solution is 2 molal.