Question

Explain the degree of dissociation?

Answer 1

Hint: When an acid is dissolved in water, the covalent bond between the electronegative atom and the hydrogen atom is broken by heterolytic fission. As a result, it gives a proton \[{H^ + }\]and a negative ion. Dissociation takes place in the above example. Here the word “degree” means “extent”.

Complete answer:
- Dissociation in chemistry can be defined as a general process in which molecules or ionic compounds, such as complexes or salts, split or separate into smaller particles such as atoms, ions or radicals, generally in a reversible manner.
- The extent to which the dissociation occurs is known as degree of dissociation.
- The degree of dissociation can be defined as the fraction of solute molecules that dissociates.
- It can also be defined as the generation of current carrying free ions which dissociate from the fraction of the solute at a given temperature.
- It is usually defined by the Greek symbol \[\alpha \] .
- It can be defined more accurately as the number of solute particles that dissociate into ions, radicals, smaller molecules or compounds, per mole.
- Degree of dissociation of a strong acid and a strong base will be very close to 1. Weaker acids and bases have lower degree of dissociation.
- Factors that affect degree of dissociation are given below.
(i) The value of \[\alpha \]for strong electrolyte is nearly 1 and for weak electrolyte is less than 1, under normal dilution.
(ii) The nature of the solvent, whether it is polar or nonpolar, also affects the degree of dissociation.
(iii) The degree of dissociation is inversely proportional to the concentration of the solution and the weight of the solution but it is directly proportional to the dilution of the solution and the amount of solvent present in the solution.
(iv) The degree of dissociation of an electrolyte increases with the increase in temperature in a solution.

Note:
There is a difference between the degree of dissociation and the dissociation constant. The degree of dissociation is the dissociation of molecules into smaller particles, ions or radicals, whereas dissociation constant is the ratio of the dissociated ions to the undissociated or the original molecules.