Question

Calculate the mass of urea (NH,CONH,) required in making 2.5 kg
of 0.25 molar aqueous solution.​

Answer 1

Answer:

Given that.

Mass of solution = 2.5 Kg.

Molality = 0.25 m.

Molar mass of urea (NH2CONH2) =14 + 2 × 1 + 12 + 16 + 14 + 2 × 1 = 60 g mol−1.

Let mass of urea (NH2CONH2) = w gram.

Number of moles of urea = w / 60 = 0.01667 mol.

Mass of urea in Kg = w/1000 = 0.001w kg.

Explanation:

hope it helps u .

Answer 2

Answer:

Given that

Mass of solution = 2.5 Kg

Molality = 0.25 m

Molar mass of urea (NH2CONH2) =14 + 2 × 1 + 12 + 16 + 14 + 2 × 1 = 60 g mol−1

Let mass of urea (NH2CONH2) = w gram

Number of moles of urea = w / 60 = 0.01667 mol

Mass of urea in Kg = w/1000 = 0.001w kg

Mass of solvent = total mass - mass of solute = 2.5 - 0.001 w kg

Molality=no of moles of solute / mass of solvent(kg)

w = 37 g of urea