Question

Calculate the molality of a solution of copper(II) sulfate, CuSO4, where 11.25 g of the crystals have been dissolved in 325 g of water.

Answer 1

0.216 mol.Kg⁻¹

Step-by-step explanation:

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Answer 2

Answer:
Molality = 0.216 mol.Kg⁻¹

Solution:
Molality is the amount of solute dissolved per Kg of solvent. It is expressed as,

Molality = Moles / Kg of Solvent ----- (1)

Data Given;
Mass = 11.25 g

Mass of Solvent = 325 g = 0.325 Kg

First calculate Moles for given mass as,

Moles = Mass / M.mass

Moles = 11.25 g / 159.6 g.mol⁻¹

Moles = 0.0704 mol

Now, putting value of Moles and Volume in eq. 1,

Molality = 0.0704 mol ÷ 0.325 Kg

Molality = 0.216 mol.Kg⁻¹