(a) Define the following terms: i) Ideal solution ii) Azeotrope iii) Osmotic pressure (b) A solution of glucose (C$_6$H$_{12}$O$_6$) in water is labelled as 10% by weight. What would be the molality of the solution? (Molar mass of glucose = 180 g mol$^{-1}$)

(a)(i) A solution obeying Raoult's law at all concentrations, with ΔH_mix = 0 and ΔV_mix = 0. (ii) A constant-boiling mixture distilling with unchanged composition. (iii) Excess pressure that just stops osmosis. (b) m ≈ 0.617 mol kg⁻¹

CBSE Class 12 · 2013 · SolutionsLong Answer

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(a) Define the following terms:
i) Ideal solution
ii) Azeotrope
iii) Osmotic pressure
(b) A solution of glucose (C

_{6}

_{12}

_{6}

) in water is labelled as 10% by weight. What would be the molality of the solution? (Molar mass of glucose = 180 g mol

^{- 1}

)

Solution

(a)(i) Ideal solution: one that obeys Raoult's law over the whole concentration range, for which

Δ_{mi x} H = 0

and

Δ_{mi x} V = 0

.
(ii) Azeotrope: a binary liquid mixture that boils at a constant temperature with identical liquid and vapour compositions, so it cannot be separated by fractional distillation.
(iii) Osmotic pressure: the minimum excess pressure applied on a solution that just prevents the inflow of solvent through a semipermeable membrane.
(b) 10% by weight: 10 g glucose + 90 g water.

m = \frac{10/180}{0.090} = \frac{0.05556}{0.090}

m = 0.617 mol kg^{- 1}

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CBSE Class 12 · 2013 · SolutionsLong Answer

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