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

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter Solutions. This page offers a step-by-step solution to the specific question from Exercise 2, Question 16: . With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 16:

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 p20= 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 = x2 p20

= 0.456 × 105.2

= 47.97 kPa

Partial pressure of octane,p2 = x2 p20

= 0.544 × 46.8 = 25.46 kPa

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

= 47.97 + 25.46

= 73.43 kPa


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Comments

  • NATS
  • Oct 04, 2023

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


  • Nayan M J
  • Jun 26, 2019

It was a suitable answer


  • Fucker
  • May 15, 2019

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


  • Aakarshan
  • Apr 24, 2019

The yellow background soothes me.


  • chutiya
  • Apr 22, 2019

dhanywad


  • Procrastinator
  • Mar 12, 2019

God bless ur soul


  • Shivam Yadav
  • Mar 09, 2019

Wow thanks


  • Alfin
  • Mar 01, 2019

p1 = x2 p20??


  • Samoon karamat
  • May 30, 2018

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


  • Rama
  • Oct 17, 2017

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....