Question

What are the types of equilibrium?

Answer 1

Equilibrium:

1. It is a condition of an isolated system where there is no propensity towards change.
2. The forward rate of reaction is equal to the rate of backward reaction.
3. The chemical composition of a substance is constant.
4. Example: The rate of evaporation is equal to the rate of condensation. It is represented by:
   ${\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\rightleftharpoons {\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$, where Double half arrow shows that the process in both directions is going simultaneously.

Types:

1. Dynamic equilibrium: In a closed vessel, the reactants convert into the product at a particular temperature with the decrease in the reactant concentration and increase in the product concentration. After some time, the rate of forwarding reaction is equal to the rate of backward reaction at constant concentration. This is known as dynamic equilibrium.
2. Physical equilibrium: The equilibrium involves the phase transformation process of the state of matter like $\mathrm{solid}\rightleftharpoons \mathrm{liquid},\mathrm{liquid}\rightleftharpoons \mathrm{gas},\mathrm{gas}\rightleftharpoons \mathrm{solid}$.
3. Chemical equilibrium: There are mainly three conditions for the chemical equilibrium, first is the concentration of the reactants is negligible, second is the small amount of product is formed with most of the reactant unchanged at the equilibrium stage, and the last is comparable results of concentration of reactant and product at equilibrium.
4. Ionic equilibrium: It is the involvement of the physical and chemical equilibrium along with ionic equilibrium in the aqueous solution.
5. Homogenous equilibrium: All the reactants and products are in the same phase. For example,
   ${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\rightleftharpoons 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$. In this reaction, the reactants and the products are in the same phase.
6. Heterogeneous equilibrium: The reactants and the products are not in the same state of matter. For example, $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)\rightleftharpoons {\mathrm{Ca}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)$. In this reaction, the equilibrium reaction is between a solid and aqueous phase.