Question

What's the molality of a solution with 120 g of NaCl and 30 kg of water?

Answer 1

Answer: The correct option is A) 0.068 m

Explanation:

Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molarity:

$\text{Molality of solution}=\frac{\text{Given mass of solute}}{\text{Molar mass of solute}\times \text{Mass of solvent (in kg)}}$ .....(1)

We are given:

Given mass of NaCl = 120 g

Molar mass of NaCl = 58.45 g/mol

Mass of solvent = 30 kg

Putting values in equation 1, we get:

$\text{Molality of NaCl}=\frac{120}{58.44\times 30}\\\\\text{Molality of NaCl}=0.068m$

Hence, the correct option is A) 0.068 m