Chemistry Carboxylic Acids MDCAT 2015
PMDC Verified Question 80 of 94
An organic acid 'z' reacts separately with sodium bicarbonate, sodium hydroxide and sodium carbonate. Which one of the following represent the structure of 'z'
A
\( \text{HCOOC}_2\text{H}_5 \)
B
\( \text{CH}_3\text{CH}_2\text{OH} \)
C
\( \text{CH}_3\text{-CH=CH}_2 \)
D
\( \text{H}_3\text{C-CH}_2\text{-COOH} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( \text{H}_3\text{C-CH}_2\text{-COOH} \)
Concept:

Only carboxylic acids possess sufficient acidity to react with weak bases like sodium bicarbonate and sodium carbonate to release \( \text{CO}_2 \) gas.

Formula:

$$ \text{R-COOH} + \text{NaHCO}_3 \longrightarrow \text{R-COONa} + \text{H}_2\text{O} + \text{CO}_2\uparrow $$

Solution:

  • Option A is an ester (ethyl formate); it is neutral and unreactive with bases under normal conditions.


  • Option B is an alcohol (ethanol); it can react with strong metals but not weak bases like \( \text{NaHCO}_3 \).


  • Option C is an alkene (propene); it does not undergo acid-base reactions.


  • Option D is propanoic acid (\( \text{CH}_3\text{CH}_2\text{COOH} \)), a carboxylic acid that readily neutralizes \( \text{NaOH} \), \( \text{NaHCO}_3 \), and \( \text{Na}_2\text{CO}_3 \).


Why other options are incorrect:

Only the molecule containing the carboxyl group (\( -\text{COOH} \)) possesses the necessary acid strength.

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