Question:medium

Identify the correct order of acidic strength:

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Remember the general rule for common organic liquids: Carboxylic acids > Water > Alcohols. The only common alcohol stronger than water is Methanol.
Updated On: May 30, 2026
  • $CH_3COOH > C_2H_5OH > H_2O$
  • $H_2O > CH_3COOH > C_2H_5OH$
  • $CH_3COOH > H_2O > C_2H_5OH$
  • $C_2H_5OH > H_2O > CH_3COOH$
Show Solution

The Correct Option is C

Solution and Explanation

Step 1: Understanding the Concept:
Acidic strength is determined by the stability of the conjugate base formed after losing a proton (\(H^+\)). A more stable conjugate base corresponds to a stronger acid.
Step 2: Detailed Explanation:
1. Acetic acid (\(CH_3COOH\)): The conjugate base is the acetate ion (\(CH_3COO^-\)). It is stabilized by resonance between two electronegative oxygen atoms. Thus, it is the strongest acid among the given options.
2. Water (\(H_2O\)): The conjugate base is the hydroxide ion (\(OH^-\)).
3. Ethanol (\(C_2H_5OH\)): The conjugate base is the ethoxide ion (\(C_2H_5O^-\)). The ethyl group (\(C_2H_5\)) has an electron-donating \(+I\) effect, which increases electron density on the oxygen atom, making the ethoxide ion less stable than the hydroxide ion.
4. Generally, carboxylic acids are stronger than water, and water is a stronger acid than most simple alcohols (except methanol).
Step 3: Final Answer:
The correct order is \(CH_3COOH>H_2O>C_2H_5OH\).
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