Among the following acids which has the lowest pKa value? (a) CH3 COOH (b) HCOOH (c) (CH3)2 CH-C

step 1 Question is among the following acids which has the lowest PCA value. So as the value of PCA dec

Among the following acids which has the lowest pKa value?...

Among the following acids which has the lowest pKa value?
(a) $\mathrm{CH}_{3} \mathrm{COOH}$
(b) $\mathrm{HCOOH}$
(c) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-\mathrm{COOH}$
(d) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COH}$

Key Concepts

Acid Dissociation Constant (pKa)

The pKa is a quantitative measure of the strength of an acid in solution; it is defined as the negative logarithm of the acid dissociation constant (Ka). A lower pKa value indicates a stronger acid because it signifies a greater tendency to donate a proton. This concept is fundamental in predicting and comparing the acidities of different compounds.

Conjugate Base Stability

Acid strength is largely determined by the stability of its conjugate base. A more stable conjugate base, which can better accommodate and delocalize the negative charge, corresponds to a stronger acid. Factors such as resonance stabilization and electronegativity play key roles in this stability.

Inductive Effects

Inductive effects refer to the electron-donating or electron-withdrawing influence of substituent groups attached to the acidic molecule. Electron-withdrawing groups stabilize the negative charge on the conjugate base, thereby enhancing acidity (lowering pKa), while electron-donating groups have the opposite effect, reducing acidity by destabilizing the conjugate base.

Carboxylic Acid Functional Group

Carboxylic acids contain the carboxyl group (-COOH), which is a common acidic functional group in organic chemistry. The inherent ability of the carboxylate ion (the conjugate base) to delocalize charge across the oxygen atoms through resonance is a key feature that contributes to the acidity of these compounds.

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