Question

Explain why ionic attractions are weaker in media with high dielectric constants, e. g., aqueous buffers

Answer 1

Ionic interactions arise from electrostatic attraction between two groups of opposite charge. This energy is inversely proportional to the dielectric constant of the medium.

The higher the dielectric constant of a solvent, the more polar it is. eg: The dielectric constant of water is higher than that of methanol; water is more polar than methanol.

The ionic strength of a solution is a measure of the concentration of ions in that solution. Ionic compounds, when dissolved in water, dissociate into ions. The total electrolyte concentration in solution will affect important properties such as the dissociation constant or the solubility of different salts.

According to Coulomb's Law:

F∝q1q2 /d2 ϵ
This law, is also applied to chemistry and ionic bonds, since they are all characterized by electrostatic interactions.

the strength of a ionic bond is directly proportional to the product of the charges on the ions, inversely proportional to the square of their distance, and inversely proportional to the dielectric constant of the solvent. In vacuum, the dielectric constant is ϵ=1.

So, if the dielectric constant is higher , the electrostatic force will be less and hence the ion - ion interaction will be less or weaker .