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Chemical Equilibrium

A Tutorial on Chemical Equilibrium: Notes, Figures and Problems with Solutions

Target Audience: These notes on Atomic Structure are meant for college freshmen, or high school students in Grades 11 or 12.

They might be of use to Indian students preparing for the ISC or CBSE Class 11 and 12 Examinations, IIT JEE (main and advanced), AIEEE; students from across the world preparing for their A Level Examinations, IB (International Baccalaureate) or AP Chemistry.

This compilation of notes has been prepared by Ayushi Patel of IIT Gandhinagar.

Complete Tutorial with Problems, Figures and Solutions : 

A Tutorial on Chemical Equilibrium

Summary and Outline of Notes: Here's a quick recap of the outline of topics which were covered in this tutorial



Chemical Equilibrium : Chemical Equilibrium occurs when the amount of reactants and products are not changing over time.

Some points about chemical equilibrium :

1)Rate of forward reaction = rate of backward reaction.

2)At equilibrium,properties like pressure, concentration,color ,intensity etc becomes constant.

3)Chemical equilibrium always occurs in a closed system.

4)A chemical equilibrium is dynamic ,both forward and backward reaction keep on occuring.

5)Chemical reaction can be obtained from both forward or backward side.

6)Catalyst does not affects the equilibrium condition but it can increase the rate of forward and backward reaction by the same rate.

Law of mass action :

It states that the rate of a chemical reaction is proportional to the product of active masses. Active masses means the mass raised to the power of coefficient of the species in the equation denoting chemical reaction.


Le Chatelier’s Principle :

This principle helps to understand what can be the affects of changes made in equilibrium.

It states that whenever changes are made in an equilibrium,the equilibrium will shift in such direction ,in which direction it can cancel out that change.

Concentration, Pressure/Volume, Temperature Changes:

These are some of the important factors which affect the chemical equilibrium.

A Quick Look at a few of the problems we will learn how to solve:


Under certain temperature conditions,the equation existed in equilibrium.Initially there were 12 moles and 16 moles of nitrogen and oxygen and 8 moles of nitrogen oxide are formed.Find the equilibrium constant for the reaction. 


Calculate the degree of dissociation for the following reaction ,with equilibrium constant 0.095 molL-1 . and volume 2L and 80 g of ammmonia initially present .Take molecular weight of A2B as 30 g.

2A2B ⇌ 2AB + A2


For the given reaction,at 1127 0C, the value of equilibrium constant is 4.7.Find the value of kp

for the reaction

H2O + CH4  ⇌ CO + 3H2


4.8 g of HCONH2 was obtained at a temperature with of 127 0C volume 2L and 3 atm pressure at equilibrium.Calculate the degree of dissociation of  HCONH2  for the reaction.

HCONH2(g) ⇌ NH3(g)+ CO(g)


R ⇌ P + 2Q

The value of kc at any a particular instant for the above reaction is 3 .Find in which direction will the reaction prgress if total pressure at equilibrium is 0.56 atm and initial pressure is 0.3 atm.Given that the temperature is 300 k.

..And many more challenging questions