Question

what mass of 0.5 molal urea solution contains 0.15 mole urea

Answer 1

Molality of a solution is calculated in the following way:

molality = moles of solute/ kg of solvent

Therefore mass of solvent =molality/moles

Molality = 0.5 molal
Moles = 0.15 moles

Thus, mass = 0.5/0.15

= 3.33 kg

Therefore the mass of 0.5 molal urea that contains 0.15 moles is 3.33 kg urea