On the basis of given data:
Mass of solvent (benzene) = 100 gm or 0.1 Kg
Molar mass of solute (solid) = 89 g/mol
Increase in boiling point (deltaTb) = 2.42 degree C
The boiling point elevation constant k = 2.53 C.kg/mol
There is a need to determine the mass of the solid to be added, the elevation in boiling point is proportional to the m (molality) of the solute;
ΔTb = k.m
Here, m that is molality = moles of solute/kg of solvent
Therefore,
ΔTb = k (benzene) × moles of solid/kg of benzene
2.42 = 2.53 × moles of solid/0.1
moles of solid = 0.0956 moles
The molar mass of solid = 89 g/mol
Thus, the mass of solid = 0.0956 moles × 89 g/mol
= 8.508 g
Thus, the mass of solid to be added is 8.508 g.
