Question

An aqueous solution of urea freezes at –0.186°C, K_f for water = 1.86 K kg mol^–1, K_b for water = 0.512 K kg mol^–1. The boiling point of urea solution will be ______.

Options

• 373.065 K

• 373.186 K

• 373.512 K

• 373.0512 K

Answer 1

An aqueous solution of urea freezes at – 0.186°C, K_f for water = 1.86 K kg mol^–1, K_b for water = 0.512 K kg mol^–1. The boiling point of urea solution will be 373.0512 K.

Explanation:

0 − (−0.186) = 1.86 m

∴ m = `(0.186)/1.86` = 0.1

ΔT_b = K_b m

= 0.512 × 0.1

= 0.0512

T − T° = 0.0512

T = 0.0512 + T°

= 0.0512 + 373

= 373.0512 K