Degree of Dissociation - Practice Questions & MCQ

Degree of dissociation: It is the extent to which an electrolyte gets dissociated in a solvent. It is shown by ?.

Degree of dissociation(?) depends on the following factors:

• Nature of solute and solvent: For strong electrolytes, ? is more than that for weak electrolytes.
• ? ∝ Dielectric constant of solvent
  That is, greater the dielectric constant of a solvent more will be ionization of electrolyte in it.
• The degree of dissociation of weak electrolyte ∝ Dilution that is ? is maximum at infinite dilution.
• ? ∝ 1/Concentration
• ? ∝ Temperature

In equilibrium, observed molar mass or average molar mass of the reactant is the total mass of the mixture divided by the total number of moles.

             
Initially:  1            0
Equil:    1 - ?       n?

In the equilibrium system, the observed molar mass of the reactant is always different than the actual mass. Thus, when reaction is reversible, then observed mass vary. In a chemical reaction, some amount of this reactant gets convert into product, thus observed mass is different than actual mass.

For example:

In this reaction, original molar mass of N₂O₄ = 92g/mol. But thee observed molar mass at equilibrium is 80g/mol. The observed molar mass is less than original molar mass as during the reaction some amount of N₂O₄ is converted into NO₂.

Vapour Density

Similarly, observed density of the substance is different than the actual density.

Thus, we know: 

Vapour density = Molar mass/2