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Heptane and octane form an ideal solution. At 373 K, the vapour pressu...

Heptane and octane form an ideal solutio | Class 12 Chemistry Chapter Solutions, Solutions NCERT Solutions

Question:

Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are 105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure of a mixture of 26.0 g of heptane and 35 g of octane?

Answer:

Vapour pressure of heptane p₁⁰ = 105.2 kPa

Vapour pressure of octane p_²⁰= 46.8 kPa

As we know that, Molar mass of heptane (C₇H₁₆) = 7 × 12 + 16 × 1 = 100 g mol ^{- 1}

∴ Number of moles of heptane = 26/100 mol = 0.26 mol

Molar mass of octane (C₈H₁₈) = 8 × 12 + 18 × 1 = 114 g mol^{- 1}

∴ Number of moles of octane = 35/114 mol = 0.31 mol

Mole fraction of heptane, x₁ = 0.26 / 0.26 + 0.31

= 0.456

And, mole fraction of octane, x₂ = 1 - 0.456 = 0.544

Now, partial pressure of heptane, p₁= x₂p₂⁰

= 0.456 × 105.2

= 47.97 kPa

Partial pressure of octane,p₂= x₂p₂⁰

= 0.544 × 46.8 = 25.46 kPa

Hence, vapour pressure of solution, p_total= p1 + p2

= 47.97 + 25.46

= 73.43 kPa

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Comments

NATS
2023-10-04 22:18:47

35/114=0.30 .....but why 0.31?

Nayan M J
2019-06-26 18:22:24

It was a suitable answer

Fucker
2019-05-15 10:44:32

There is a mistake for finding partial pressure. It should have been written Pa = xapÂ°a

Aakarshan
2019-04-24 19:37:56

The yellow background soothes me.

chutiya
2019-04-22 17:19:50

dhanywad

Procrastinator
2019-03-12 01:11:32

God bless ur soul

Shivam Yadav
2019-03-09 14:41:41

Wow thanks

Alfin
2019-03-01 09:58:20

p1 = x2 p20??

Samoon karamat
2018-05-30 11:12:01

Thanks for this help ....best &simple solution

Rama
2017-10-17 12:07:26

Thanks for this help Best site!!!!!!

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Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 16: Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid componen....

Heptane and octane form an ideal solutio | Class 12 Chemistry Chapter Solutions, Solutions NCERT Solutions

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