According to the boiling point elevation formula:
ΔTb = i * Kb * m
- when i is the van't Hoff factor for sucrose = 1
as the sucrose is an organic molecule so, there is no dissociation in water so i = 1
- Kb is the ebullioscopic constant of the solvent (water) = 0.512°C Kg mol-1
- and when m is the molality = moles sucrose / Kg water
so, we need first to get moles sucrose = mass/molar mass
= 759 g / 342.3 g/mol
= 2.22 moles
∴ m = 2.22 moles / 0.3 Kg
= 7.4 mol/kg
by substitution on ΔTb:
∴ΔTb = 1 * 0.512 * 7.4
= 3.8
∴Tb = 100 °C + 3.8 = 103.8 °C
