Question

Identify the correct order of acidic strength:

• A. $CH_3COOH > C_2H_5OH > H_2O$
• B. $H_2O > CH_3COOH > C_2H_5OH$
• C. $CH_3COOH > H_2O > C_2H_5OH$
• D. $C_2H_5OH > H_2O > CH_3COOH$

Hint:

Remember the general rule for common organic liquids: Carboxylic acids > Water > Alcohols. The only common alcohol stronger than water is Methanol.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Acidic strength depends on the stability of the conjugate base formed after the loss of a proton ($H^+$). The more stable the conjugate base, the stronger the acid.

Step 2: Detailed Explanation:

• Acetic acid ($CH_3COOH$): It is a carboxylic acid. Its conjugate base (acetate ion) is stabilized by resonance between two oxygen atoms, making it the strongest acid in this group.
• Water ($H_2O$): It is neutral but more acidic than simple alcohols.
• Ethanol ($C_2H_5OH$): In alcohols, the alkyl group ($C_2H_5$) exerts an electron-releasing inductive effect ($+I$ effect), which destabilizes the conjugate base (ethoxide ion) and makes it less acidic than water.

Step 3: Final Answer:
The correct order is $CH_3COOH > H_2O > C_2H_5OH$.