Equilibrium Class 11 Notes - Chapter 7

Equilibrium is attained when molecules leaving the liquid to vapor equals the molecules returning to the liquid from vapor. Kc is the equilibrium constant. It is defined as the concentration of products divided by the concentration of reactants where each term is raised to stoichiometric coefficient.
Kc = [C]c[D]d/[A]a[B]b

Le Chatelier’s Principle

It states that change in any factor such as concentration, pressure, temperature, etc. causes the equilibrium to shift in such a direction to counteract or reduce the effect of a change.


Electrolytes are substances which conduct electricity in aqueous solution. Some examples of electrolytes are bases, salts, and acids. The electricity conducted in aqueous solution is due to cations and anions produced by the ionization or dissociation of electrolytes in the solution.

Lewis Acid and Base

A Lewis acid is a species containing an empty orbital which can accept an electron pair (an electrophile) from a Lewis base and forms a Lewis adduct.

A Lewis base is a species having a filled orbital which contains an electron pair that will not be involved in bonding but might form a dative bond with Lewis acid.


Few Important Questions

  1. While writing the equilibrium constant expression, you can ignore pure liquids and solids. Why? Explain.
  2. Tick mark Lewis acids from the following

H2O, H+, NH+4 and BF3

  1. Below are Brönsted bases. Write the conjugate acids for the same.

NH2 , HCOO , NH3

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