An aqueous solution of 2% non-volatile s | Class 12 Chemistry Chapter Solutions, Solutions NCERT Solutions

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Academic session 2026-27, Chapter 1 in the current curriculum.

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 15:

An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?

. 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 15:

An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling point of the solvent. What is the molar mass of the solute?

Answer:

Here,

Vapour pressure of the solution at normal boiling point (p1) = 1.004 bar  (Given)

Vapour pressure of pure water at normal boiling point (p10) = 1.013 bar

Mass of solute, (w2) = 2 g

Mass of solvent (water), (w1) = 100 - 2 = 98 g

Molar mass of solvent (water), (M1) = 18 g mol - 1

According to Raoult's law,

(p10 - p1) / p10    =  (w2 x M1 ) / (M2  x w1 )

(1.013 - 1.004) / 1.013 =  (2 x 18) / (M2 x 98 )

0.009 / 1.013  =   (2 x 18) / (M2 x 98 )

M2  =  (2 x 18 x 1.013) / (0.009 x 98)

M2  = 41.35 g mol - 1

Hence, the molar mass of the solute is 41.35 g mol - 1.


Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

  • Read the question carefully and focus on the core concept being asked.
  • Reference examples and data from the chapter when answering questions about Solutions.
  • Review previous year question papers to get an idea of how such questions may be framed in exams.
  • Practice answering questions within the time limit to improve your speed and accuracy.
  • Discuss your answers with your teachers or peers to get feedback and improve your understanding.

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Comments

  • nishant
  • Jul 14, 2021

there is a little mistake in formula right formula is (p1* - p1) / p1 = (w2 x M1 ) / (M2 x w1 ) by this formula the answer is 40.9 which is correct also mention in NCERT question 2.15


  • Reena Roy
  • Jul 18, 2019

Very helpful


  • Anupama
  • Jul 06, 2019

In the question,it's only given as a solvent.Why did u take it as water?


  • Veer Pratap Singh Laungwal
  • May 30, 2019

Thank you so much very informative


  • Satya prakash satapathy
  • May 26, 2019

Thanks


  • Pooja
  • May 22, 2019

Thx


  • Arushi
  • May 05, 2019

Thanks


  • pratap
  • May 05, 2019

isme vapour presure water ka to diya hi na h


  • Kr shiddartha
  • Apr 23, 2019

Thanks


  • Prashant
  • Apr 21, 2019

Thanks


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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 15: An aqueous solution of 2% non-volatile solute exerts a pressure of 1.004 bar at the normal boiling p....

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