Question:
Correct order of acidic strength:
Correct order of acidic strength:
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Carboxylic acids are generally stronger than phenols, and phenols are stronger than alcohols. Remember the sequence: $RCOOH>ArOH>H_2O>ROH$.
Updated On: Apr 20, 2026
- Phenol>Ethanol>Acetic acid
- Acetic acid>Phenol>Ethanol
- Ethanol>Phenol>Acetic acid
- Phenol>Acetic acid>Ethanol
- Acetic acid>Ethanol>Phenol
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The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
Acidic strength depends on the stability of the conjugate base formed after losing a proton ($H^+$). The more stable the conjugate base, the stronger the acid.
Step 2: Detailed Explanation:
1. Acetic Acid ($CH_3COOH$): Forms the acetate ion ($CH_3COO^-$). The negative charge is delocalized over two highly electronegative oxygen atoms through resonance. This is very stable, making it the strongest acid in this group.
2. Phenol ($C_6H_5OH$): Forms the phenoxide ion ($C_6H_5O^-$). The negative charge is delocalized over the benzene ring. While resonance occurs, the charge resides on carbon atoms (less electronegative than oxygen), so it is less stable than the acetate ion.
3. Ethanol ($C_2H_5OH$): Forms the ethoxide ion ($C_2H_5O^-$). There is no resonance stabilization. In fact, the ethyl group has an $+I$ (inductive) effect, which pushes electron density toward the oxygen, making the negative charge \textit{less} stable.
Step 3: Final Answer:
The correct order of acidic strength is Acetic acid>Phenol>Ethanol.
Acidic strength depends on the stability of the conjugate base formed after losing a proton ($H^+$). The more stable the conjugate base, the stronger the acid.
Step 2: Detailed Explanation:
1. Acetic Acid ($CH_3COOH$): Forms the acetate ion ($CH_3COO^-$). The negative charge is delocalized over two highly electronegative oxygen atoms through resonance. This is very stable, making it the strongest acid in this group.
2. Phenol ($C_6H_5OH$): Forms the phenoxide ion ($C_6H_5O^-$). The negative charge is delocalized over the benzene ring. While resonance occurs, the charge resides on carbon atoms (less electronegative than oxygen), so it is less stable than the acetate ion.
3. Ethanol ($C_2H_5OH$): Forms the ethoxide ion ($C_2H_5O^-$). There is no resonance stabilization. In fact, the ethyl group has an $+I$ (inductive) effect, which pushes electron density toward the oxygen, making the negative charge \textit{less} stable.
Step 3: Final Answer:
The correct order of acidic strength is Acetic acid>Phenol>Ethanol.
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