Question

What is the molality of a solution containing 4.0 moles of solute in 3.2 kg of solvent? Round to the nearest tenth. Don't forget the units.

Answer 1

Molality is the moles of solute per Kg of solvent. Simply:
m=moles solute/Kg solvent

m=(4.0 moles solute/3.2 Kg solvent)
m=1.25

m=1.3 mol/Kg or 1.3 molal [rounded to nearest tenth]


(FYI - molarity is found by moles of solute divided by liters of solution)

Answer 2

1.3 mol/kg is the molality of a solution.

Step-by-step explanation:

`Molality=\frac{\text{moles of solute}}{\text{Mass of the solvent (kg)}}`

Moles of solute = 4.0 moles

Mass of the solvent = 3.2 kg

`Molality=(4.0 mol)/(3.2 kg)=1.25 mol/kg\approx 1.3 mol/kg`

1.3 mol/kg is the molality of a solution containing 4.0 moles of solute in 3.2 kg of solvent.