Question

What will be the decreasing order of basic strength of the following conjugate bases?
\( \text{OH}^-, \, \text{R}^-, \, \text{CH}_3\text{COO}^-, \, \text{Cl}^- \)

• A. \( \text{Cl}^- > \text{OH}^- > \text{R}^- > \text{CH}_3\text{COO}^- \)
• B. \( \text{R}^- > \text{OH}^- > \text{CH}_3\text{COO}^- > \text{Cl}^- \)
• C. \( \text{OH}^- > \text{R}^- > \text{CH}_3\text{COO}^- > \text{Cl}^- \)
• D. \( \text{Cl}^- > \text{R}^- > \text{OH}^- > \text{CH}_3\text{COO}^- \)

Answer 1

The Correct Option is B

Conjugate Acid Strength and Basic Strength:

Basic strength of a conjugate base is inversely proportional to the strength of its conjugate acid. Strong acids yield weak conjugate bases, and weak acids yield strong conjugate bases.

Acidity Order of Conjugate Acids:

To ascertain the basic strength of conjugate bases, examine the acidity of their corresponding conjugate acids:

• For \( \text{OH}^- \): Conjugate acid is \( \text{H}_2\text{O} \), a weak acid.
• For \( \text{RO}^- \): Conjugate acid is \( \text{R-OH} \) (alcohol), generally a weaker acid than water.
• For \( \text{CH}_3\text{COO}^- \): Conjugate acid is \( \text{CH}_3\text{COOH} \) (acetic acid), stronger than water and alcohols.
• For \( \text{Cl}^- \): Conjugate acid is \( \text{HCl} \), a strong acid.

Determining Basic Strength Order:

Based on the preceding analysis, the descending order of basic strength is:

\[ \text{RO}^- > \text{OH}^- > \text{CH}_3\text{COO}^- > \text{Cl}^- \]

Final Determination:

The established order of decreasing basic strength is:

\[ \text{RO}^- > \text{OH}^- > \text{CH}_3\text{COO}^- > \text{Cl}^- \]

This corresponds to Option (2).