In: Chemistry
Discuss effects of structure and of the medium on the strengths of acids and bases. Use examples to illustrate your explanation.
To compare the strenght of acids, we examine their conjugate bases. A congugate base is stronger if it is able to share its electron pair. Because they influence electron density,the following structural effects influence basicity.Dispersion of negative charge in a conjugate base helps it to stabilize. Thus any factor influencing charge dispersion becomes a factor increasing the acidity of the acid.
Following is the order of the factors affecting the conjugate base to stabilize: structural effects -
inductive effect<electronegativity<atomic size<resonance
The medium also affects the strength of the acids and bases. The solvent that helps stabilizing the conjugate base is the one that helps in increasing the acidity. The stabilizing factors are -
H-bonding> ion-dipole interacton etc.