Question

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

A)

0.068

B)

0.004

C)

0.25

D)

6.8

Answer 1

Answer: The correct option is A) 0.068 m

Step-by-step 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}* \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}=(120)/(58.44* 30)\\\\\text{Molality of NaCl}=0.068m`

Hence, the correct option is A) 0.068 m