Two pairs of compounds are given below, which one in each is more acidic and why? (i) \(\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\) and \(\mathrm{H}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\) (ii) \(\mathrm{BrCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\) and CCC(C)CCO

Electronegativity plays a crucial role in determining the acidity of organic compounds. Acidity is often gauged by the strength of a compound to donate a proton (H+), and this is greatly influenced by the stability of the resulting conjugate base. The more stable the conjugate base, the stronger the acid.

An atom's electronegativity can stabilize the negative charge of a conjugate base by distributing the charge over a larger volume or by an attractive force with the negative charge. For instance, in the compounds ewline BrCH_2CH_2CH_2OH ewline and ewline H_3COCH_2CH_2CH_2OH, the presence of oxygen, a highly electronegative atom, in the latter compound makes it more acidic. This is because oxygen is better able to stabilize the negative charge on the conjugate base that forms when the compound donates a proton.

The resonance effect involves the delocalization of electrons within a molecule, which can alter its acidity. When a conjugate base is capable of delocalizing its negative charge through resonance structures, it becomes more stable, therefore enhancing the acidity of the original compound.

For instance, a carboxylic acid is more acidic than an alcohol because the negative charge on the carboxylate anion (the conjugate base) is resonance-stabilized between two oxygen atoms. Although not directly applicable to the given exercise, understanding this concept can help predict acidity in more complex organic molecules.

The inductive effect refers to the electronic influence that an atom or a group of atoms exerts through sigma bonds in a molecule. Electronegative atoms or substituents can pull electron density through the bonds, stabilizing a negative charge by the inductive effect.

In the case of ewline BrCH_2CH_2CH_2OH ewline versus ewline CH_3CH_2CH(CH_3)CH_2CH_2OH, the bromine atom in the first compound exerts an inductive effect, pulling electron density towards itself and thus stabilizing the negative charge on the conjugate base that forms upon deprotonation. This enhanced stabilization due to the inductive effect of the bromine makes the first compound more acidic.

Conjugate base stability is a determining factor for the strength of an acid. If the conjugate base is stabilized by factors such as electronegativity, resonance, or inductive effects, the parent acid will be stronger as it more willingly donates a proton.

In the provided exercise, the stability of the conjugate base is influenced primarily by the electronegativity of the atoms near the deprotonation site. For ewline BrCH_2CH_2CH_2OH, ewline the bromine atom stabilizes the conjugate base due to its electronegativity and the inductive effect it exerts. This analysis allows us to conclude that this compound is more acidic compared to one with less electronegative substituents, as seen with the second compound in pair (ii).