CBSE Class 12 · 2002 · All India Compartment · SolutionsShort Answer

WhatsApp Email

"The solution of a non-volatile solute boils at a higher temperature than the pure solvent." Show this relationship on a graphic diagram.

Solution

Draw vapour pressure (y-axis) against temperature (x-axis).
The solvent's curve lies above; the solution's curve runs parallel but lower, because the non-volatile solute lowers the vapour pressure at every temperature.
A liquid boils when its vapour pressure equals the external (1 atm) line: the solvent's curve meets this line at

T_{b}^{\circ}

, the solution's only at a higher temperature

T_{b}

.
Hence

Δ T_{b} = T_{b} - T_{b}^{\circ} > 0

— the solution boils at the higher temperature (see figure).

Structure Vapour pressure vs temperature: the solution's curve lies below the solvent's, so it reaches 1 atm at a higher temperature (elevation of boiling point) — Vapour pressure vs temperature: the solution's curve lies below the solvent's, so it reaches 1 atm at a higher temperature (elevation of boiling point)

CBSE Class 12 Board · 2002 · All India Compartment · Subjective

Practise more: all CBSE board PYQs on Solutions →

More board questions on Solutions

Isotonic solutions have the same
CBSE 2024View solution →
Van't Hoff factor for Na $_{2}$ SO $_{4} \cdot$ 10H $_{2}$ O solution, assuming complete ionization, is
CBSE 2024View solution →
(a)(i) Ishan's automobile radiator is filled with 1.0 kg of water. How many grams of ethylene glycol (molar mass = 62 g mol $^{- 1}$ ) must Ishan add to get the freezing point of the solution lowered to −2.8°C? (K $_{f}$ for water = 1.86 K kg mol $^{- 1}$ )
(ii) What type of deviation fro …
CBSE 2024View solution →
(b)(i) The boiling point of water at 750 mm Hg pressure is 99.68°C. How much sucrose (molar mass = 342 g mol $^{- 1}$ ) is to be added to 500 g of water so that it boils at 100°C? (K $_{b}$ for water = 0.52 K kg mol $^{- 1}$ )
(ii) State Henry's law and write any one application of it.
CBSE 2024View solution →
Which of the following aqueous solutions will have the highest boiling point?
CBSE 2023View solution →
(i) Why is the boiling point of 1 M NaCl solution more than that of 1 M glucose solution?
(ii) A non-volatile solute 'X' (molar mass = 50 g mol $^{- 1}$ ), when dissolved in 78 g of benzene, reduced its vapour pressure to 90%. Calculate the mass of X dissolved in the solution.
(iii) …
CBSE 2023View solution →