Step 1: Understanding the Concept:
The acidic strength of carboxylic acids is determined by the stability of the conjugate base (carboxylate ion). Electron-withdrawing groups (EWGs) stabilize the negative charge on the carboxylate ion, increasing acidity.
Step 2: Key Formula or Approach:
Chlorine is a highly electronegative atom and acts as an electron-withdrawing group (–I effect).
As the number of chlorine atoms increases, the inductive effect (–I) increases, leading to greater stabilization of the conjugate base.
Step 3: Detailed Explanation:
- \(\text{CH}_3\text{COOH}\): No electron-withdrawing group; weakest acid.
- \(\text{ClCH}_2\text{COOH}\): One Chlorine atom exerts a moderate –I effect.
- \(\text{Cl}_2\text{CHCOOH}\): Two Chlorine atoms exert a stronger –I effect.
- \(\text{Cl}_3\text{CCOOH}\): Three Chlorine atoms exert the strongest –I effect, making it the most acidic.
The strength follows the trend: \(\text{Cl}_3\text{CCOOH}>\text{Cl}_2\text{CHCOOH}>\text{ClCH}_2\text{COOH}>\text{CH}_3\text{COOH}\).
Step 4: Final Answer:
The correct order of acidic strength is (C).