Cbse Chemistry Notes for 11 and 12

Supplementary Textual Material in Chemistry for Class XI
&
Class XII

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Acknowledgements
CBSE ADVISORS
Shri Vineet Joshi, I.A.S., Chairman, CBSE
Shri Shashi Bhushan, Director (Acad.), CBSE
CONVENOR & EDITOR
Prof. A.K.Bakhshi
Department of Chemistry, University of Delhi.
DEVELOPMENT TEAM
Prof. A.K.Bakhshi
Department of Chemistry, University of Delhi.
Dr. Anju Srivastava
Hindu College, University of Delhi.
Dr. Vimal Rarh
S.G.T.B. Khalsa College, University of Delhi.
Dr. Geetika Bhalla
Hindu College, University of Delhi.
Ms. Anupama Sharma
Modern School, Vasant Vihar, New Delhi.
MEMBER COORDINATOR
Dr. Srijata Das, Education Officer, CBSE

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TABLE OF CONTENTS
Class XI
Unit 5 : States of Matter

5.7.1

Kinetic Energy and Molecular Speeds

5.7.2

Maxwell-Boltzmann distribution of molecular speeds

Unit 6 : Thermodynamics
6.6.1. Second Law of Thermodynamics
6.8. Third Law of Thermodynamics

Unit 7 : Equilibrium

7.12.1 pH of Buffer Solutions

Class XII
Unit 16 :

Chemistry in Everyday Life

16.4.2.1

Antioxidants
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Unit 5: States of Matter
5.7.1 KINETIC ENERGY AND MOLECULAR SPEEDS
As you have studied in the previous section the molecules of a gas are always in motion and are colliding with each other and with the walls of the container. Due to these collisions the speeds and the kinetic energies of the individual molecules keep on changing. However at a given temperature, the average kinetic energy of the gas molecules remains constant.
If at a given temperature, n1 molecules have speed v1, n2 molecules have speed v2, n3 molecules have speed v3, and so on. Then, the total kinetic energy (EK) of the gas at this temperature is given by

where m is the mass of the molecule.
The corresponding average kinetic energy (

If the following term

Then the average kinetic energy is given by

where c is given by

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) of the