A solution of 0.450 g of urea (mol. wt. 60) in 22.5 g of water showed 0.170oC of elevation in boiling point. Calculate the molal elevation constant of water.

Weight of solute, w = 0.450 gWeight of solvent, W = 22.5 gMolecular weight of solute, m = 60Molal elevation constant Kb=?Boiling point elevation, ΔTb=0.170oCSubstituting these values in the equation Kb=m×W×ΔTb1000×w                                                                           =60×22.5×0.1701000×0.450=0.51oC