Question

6.
Boiling point of water at 750 mm Ag is 99.63°C. How much
sucrose is to be added to 500g of water such that it boils at
100°C molal elevation constant for water is 0.52k. kg mol''.​

Answer 1

Answer:

Here, elevation of boiling point ΔTb= (100 + 273) - (99.63 + 273)

= 0.37 K

Mass of water, wl = 500 g

Molar mass of sucrose (C12H22O11),

M2= 11 × 12 + 22 × 1 + 11 × 16 = 342 g mol - 1

Molal elevation constant, Kb= 0.52 K kg mol - 1

We know that:

= (0.37 x 342 x 500) / (0.52 x 1000)

= 121.67 g (approximately)

Hence, 121.67 g of sucrose is to be added.