Question

At what temperature will a sucrose solution boil if it contains 1.55 moles of sucrose in 600mL of water? kb of water is 0.51°C/m.

Answer 1

∆T=K_b×m, where m is molality (number of moles of solute per kilogramme of solvent).

If the density of water is 1g/ml, 600 ml weights 600 g or 0.6 kg.

Molality equals to

m=1.55/0.6=2.58(mol/kg)

∆T=T-T₀, where T₀ is a boiling point of pure water.

T=∆T+T₀

T=1.32+100=101.32(°C)