Answer:
The boiling point of pure X is 107.73 °C
Explanation:
Step 1: Data given
molal boiling point elevation constant Kb = 1.26 °C /m
Mass of urea = 36.1 grams
Mass of X = 550 grams = 0.550 Kg
Solution boils at 109.1 °C
Molar mass of urea = 60.06 g/mol
Step 2: Calculate moles urea
Moles urea = mass urea / molar mass urea
Moles urea = 36.1 grams / 60.06 g/mol
Moles urea = 0.601 moles
Step 3: Calculate boiling point elevation
ΔT = i*Kb*m
⇒with ΔT = the boiling point elevation = TO BE DETERMINED
⇒with i = the van't Hoff factor for urea = 1
⇒with Kb = the molal boiling point elevation constant = 1.26 °C /m
⇒with m = the molality = moles urea / mass X = 0.601 moles / 0.550 kg = 1.09 molal
ΔT = 1.26 °C/m * 1.09 m
ΔT = 1.37°C
Step 4: Calculate boiling point of pure X
ΔT = Tb (solution) - Tb (pure solvent)
1.37°C = 109.1 °C - Tb(pure solvent)
Tb pure solvent = 109.1 - 1.37 °C = 107.73 °C
The boiling point of pure X is 107.73 °C
