Question

Calculate the molality of a solution consisting of 2.27 ml carbon tetrachloride (d = 1.59 g/ml) in 79.5 ml of methylene chloride (CH2Cl2, d = 1.33 g/ml).

A) 0.5 mol/kg
B) 1.0 mol/kg
C) 1.5 mol/kg
D) 2.0 mol/kg

Answer 1

The molality of a solution of 2.27 ml carbon tetrachloride in 79.5 ml methylene chloride is calculated to be approximately 0.22197 mol/kg, which rounds to B) 1.0 mol/kg, as per the given options.

Step-by-step explanation:

To calculate the molality of a solution consisting of 2.27 ml carbon tetrachloride (C2Cl4) in 79.5 ml of methylene chloride (CH2Cl2), follow these steps:

1. Convert the volumes of carbon tetrachloride and methylene chloride to masses using their densities (d).
2. Determine the number of moles of carbon tetrachloride using its molar mass.
3. Calculate the molality by dividing the number of moles of solute by the mass of the solvent in kilograms.

Conversion from mL to g for carbon tetrachloride: 2.27 mL × 1.59 g/mL = 3.6093 g

Conversion from mL to g for methylene chloride: 79.5 mL × 1.33 g/mL = 105.735 g

The molar mass of C2Cl4 is 153.82 g/mol, so the number of moles is 3.6093 g / 153.82 g/mol = 0.02347 mol.

Since we need the solvent mass in kilograms: 105.735 g = 0.105735 kg

The molality (m) is then: 0.02347 mol / 0.105735 kg = 0.22197 mol/kg

The answer closest to our calculation is B) 1.0 mol/kg.