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

Understanding Basic Strength in Terms of Conjugate Acids:

The basic strength of a conjugate base is inversely related to the strength of its conjugate acid. A strong acid has a weak conjugate base, and a weak acid has a strong conjugate base.

Order of Acidity of Conjugate Acids:

To determine the basic strength of the conjugate bases, analyze the acidity of their conjugate acids:

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

Determine the Order of Basic Strength:

Based on the above analysis, the decreasing order of basic strength is:

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

Conclusion:

The correct order of decreasing basic strength is:

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

which corresponds to Option (2).