NEET Chemistry Notes Chemical Equilibrium – Equilibrium State
In a reversible reaction, the point at which there is no further change in concentration of reactants and products, is called equilibrium state.
Dynamic Nature Equilibrium is always dynamic in nature i.e. the reaction does not stop but goes on forward and backward directions with equal speed
It indicates that at equilibrium, rate of conversion of ice into water = rate of conversion of water into ice
Equilibrium in Physical and Chemical Processes Equilibrium in Physical Processes
The equilibrium developing between different phases or physical properties of a substance is termed as physical equilibria.
Equilibrium in Chemical Processes
In case of reversible reactions, when the concentration of reactants and products do not change with time, the reaction is called in a state of chemical equilibrium.
Law of Chemical Equilibrium
Law of mass action states, “Rate of a reaction is directly proportional to the concentration of reactants with each concentration term raised to the power equal to the respective stoichiometric coefficient”.
where, Kp= equilibrium constant in terms of partial pressure
Significance of Kc and Kp
- If Kc >103, products predominate over reactants. In other words, if Kc is very large, the reaction proceeds almost in all the ways to completion.
- If Kc <10-3, reactants predominate over products. In other words, if Kc is very small, the reaction proceeds hardly at all.
- If Kc is in the range (10-3 to 103) appreciable concentration of both reactants and products are present.
Relation between Kp and Kc
R = gas constant, T = temperature in kelvin
= gaseous moles of products – gaseous moles of reactants
Some Facts Related to Equilibrium Constant
- Equilibrium constant (Kc or Kp) does not depend on pressure, volume, concentration and catalyst but depends only upon temperature.
- Equilibrium constant for a given reaction is independent of the reaction mechanism.
- Equilibrium constant depends on stoichiometric coefficient e.g.
Units of Kc and Kp
Relation between K and
Gibbs free energy change and reaction quotient are related as