Calculate the mass of a non-volatile solute (molecular mass 40 g mol^–1) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.

Solution

Answer:
molar mass of solute, M₂ =40g mol^-1mass of octane, w₁= 114g
molar mass of solute, M₁ = 114 g mol^-1

Let the vapour pressure of pure octane be

p_{A}^{0}

then, the vapour pressure of the octane after dissolving the non volatile solute is

\frac{80}{100} p_{1}^{0}

applying the relation,

\frac{P_{A}^{0} - P_{A}}{P_{A}^{0}} = x_{A}

\frac{100 - 80}{100} = \frac{\frac{ω_{B}}{M_{B}}}{\frac{ω_{A}}{M_{A}}}

\frac{20}{100} = \frac{ω_{B}}{40} \times \frac{114}{114}

ω_{B} = \frac{40 \times 20}{100} = 8 g

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?
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Solutions

Calculate the mass of a non-volatile solute (molecular mass 40 g mol^–1) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?
(i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform, (vi) pentanol.

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NCERT Sample Papers

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Solutions

Calculate the mass of a non-volatile solute (molecular mass 40 g mol–1) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.

Some More Questions From Solutions Chapter

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 370C.

Suppose a solid solution is formed between two substances, one whose particles are very large and the other whose particles are very small. What kind of solid solution is this likely to be?

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?(i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform, (vi) pentanol.

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Calculate the mass of a non-volatile solute (molecular mass 40 g mol^–1) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.

Calculate the osmotic pressure in pascals exerted by a solution prepared by dissolving 1.0 g of polymer of molar mass 185,000 in 450 mL at 37⁰C.

Amongst the following compunds identify which are insoluble, partially soluble and highly soluble in water?
(i) phenol (ii) toluene (iii) formic acid (iv) ethylene glycol (v) chloroform, (vi) pentanol.