The boiling point of benzene is 353.23 K. When 1.80 g of a non-volatile solute was dissolved in 90 g benzene, the boiling point is raised to 354.11 K. Calculate the molar mass of the solute. (Kb for benzene is 2.53Kkgmol−1)
58.0gmol−1
Given values are:
T∘benzene=353.00K;Kb=2.53Kkgmol−1
Tb(solution)=354.00k
Wsolute=1.80g
Wsolvent=90g
The elevation in boiling point,ΔTb=Tb(solution)−T∘b(solvent)
=354.11−353.23
=0.88K
Molar mass of solute is given as
Mwsolute=Kb×1000×WsolventΔTb×Wsolvent
Mwsolute=2.53×1000×1.800.88×90=58.0gmol−1
Hence, the molar mass of solute is 58.0gmol−1