Question

AB₂ is 10% dissociated in water to A²⁺ and B⁻. The boiling point of a 10.0 molal aqueous solution of AB₂ is ______°C. (Round off to the Nearest Integer).

[Given: Molal elevation constant of water K_b = 0.5 K kg mol⁻¹ boiling point of pure water = 100°C]

Options

• 105

• 106

• 107

• 108

Answer 1

AB₂ is 10% dissociated in water to A²⁺ and B⁻. The boiling point of a 10.0 molal aqueous solution of AB₂ is 106°C.

Explanation:

ΔT_b = iK_bm

α = `("i" - 1)/("n" - 1)`

0.1 = `(("i" - 1))/((3 - 1))`

\[\ce{[AB2 -> A^{2+} + 2B^-]}\] for dissociation

i = 1.2

ΔT_b = 1.2 × 0.5 × 10

ΔT_b = 6°C

`("T"_"b")_"Solution"` = 100 + 6 = 106°C