(a) Define the following terms: (i) Molarity (ii) Molal elevation constant (Kb) (b) A solution containing 15g urea (molar mass = 60gmol⁻¹) per litre of solution in water has the same osmotic pressure (isotonic) as a solution of glucose (molar mass = 190gmol⁻¹) in water. Calculate the mass of glucose present in one litre of its solution.

(a)(i) Molarity of a solution is defined as the number of moles of solute present in one litre of the solvent (ii) Molal elevation constant (Kb) is defined as the elevation in boiling point of a solution when one mole of a non volatile solute is dissolved in one kilogram of a volatile solvent (b) Osmotic pressure π = CRT when n is the number of moles of solute present in volume V of solvent It is given that the solution of urea is isotonic with the solution of glucose, thus nGlucoseVRT = nUreaVRT = Glucose = 15/60 × 180 = 45g Hence, the mass of glucose present in one litre of its solution = 45g