Question

Find the mass in grams of aluminum nitrate, Al(NO3)3, required to mix with 750 g of water to makea 1.5m solution.

Answer 1

Answer:
Mass = 239.62 g

Step-by-step explanation:

Molality is given as,

m = Moles of Solute / Kg of Solvent --- (1)

Data Given;
Molality = 1.5 m

Mass of Solvent = 750 g = 0.75 Kg

Solving eq. 1 for Moles,

Moles = Molality × Mass of Solvent

Putting values,
Moles = 1.5 mol.Kg⁻¹ × 0.75 Kg

Moles = 1.125 mol

Calculating mass from moles,

Moles = Mass / M.mass
Or,
Mass = Moles × M.mass

Putting values,
Mass = 1.125 mol × 213 g.mol⁻¹

Mass = 239.62 g