Question

An aqueous solution is 2.00 M urea. The density of the solution is 1.029 g/ml. What is the molality concentration of urea in the solution?

Answer 1

Answer – Given, molarity [Urea] = 2.00 M ,

density of the solution = 1.029 g/ml.

We know . molarity = moles / L of solution

So, 2.00 M means 2.00 moles for 1 L solution

We know ,

1 L = 1000 mL

Now we need to calculate the mass of solution

Mass of solution = 1000 ml * 1.029 g/Ml

                             = 1029 g

Mass of solute urea= 2.00 moles * 60.06 g/mol

                               = 120.12 g

So, mass of solvent = 1029 -120.2 g

                               = 908.88 g

So, molality of urea = 2.00 moles / 0.90888 kg

                                  = 2.20 m

So, molality concentration of urea in the solution is 2.20 m