Final answer:
Molality is calculated by dividing the moles of calcium chloride by the mass of methanol in kilograms, after converting the mass to moles using its molar mass.
Step-by-step explanation:
To calculate the molality of the solution made with calcium chloride (CaCl2) and methanol (CH3OH), we first need to find the moles of CaCl2 and then divide by the mass of the solvent (methanol) in kilograms.
Molar mass of CaCl2 = 40.08 (Ca) + 2 × 35.45 (Cl) = 110.98 g/mol
Moles of CaCl2 = mass (g) / molar mass (g/mol) = 15.2 g / 110.98 g/mol
This calculation will give us the number of moles of CaCl2. Then, the mass of methanol needs to be converted from grams to kilograms: 345 g = 0.345 kg.
Molality (m) = moles of solute / mass of solvent (kg)
= Moles of CaCl2 / Mass of methanol (kg)