Question

What is the molality of a solution consisting of 4.45 mL of carbon tetrachloride (CCl4; d = 1.59 g/mL) in 85.1 mL of methylene chloride (CH2Cl2; d = 1.33 g/mL)?

Answer 1

Answer: 0.44 mol/kg

Step-by-step explanation:

Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.

`Molality=(n* 1000)/(W_s)`

where,

n = moles of solute

`W_s` = weight of solvent in g

Mass of solute
`CCl_4=Volume* density=4.45ml* 1.59g/ml=7.08g`

moles of solute =
`\frac{\text {given mass}}{\text {molar mass}}=(7.08g)/(153.82g/mol)=0.05moles`

Mass of solvent
`CH_2Cl_2=Volume* density=85.1ml* 1.33g/ml=113.2g`

Molality =
`(0.05* 1000)/(113.2g)=0.44mol/kg`

Thus molality of solution will be 0.44 mol/kg.