NEET
- Exam
- NEET
- Subject
- Chemistry
- Chapter
- Carboxylic Acid Derivatives
NEET · Chemistry · Carboxylic Acid Derivatives
Assertion: Chloro acetic acid has higher pKa value than Acetic...
Assertion: Chloro acetic acid has higher pKa value than Acetic acid.
Reason: The - I effect of Cl further stabilises the carboxylate anion formed by the loss of the proton.
Options
- ABoth assertion and reason are correct statements, and reason is the correct explanation of the assertion.
- BBoth assertion and reason are correct statements, but reason is not the correct explanation of the assertion.
- CAssertion is correct, but reason is wrong statement.
- DAssertion is wrong, but reason is correct statement.
Correct answer
D. Assertion is wrong, but reason is correct statement.
Step-by-step solution
- Fact check:
- Acetic acid: pKa (\approx 4.76)
- Chloroacetic acid: pKa (\approx 2.86) (much lower, hence stronger acid).
- Assertion: Chloroacetic acid has higher pKa than acetic acid (\rightarrow) False (it has lower pKa).
- Reason: The -1 effect of Cl stabilises the carboxylate anion formed after deprotonation (\rightarrow) True. Because chlorine is electronegative, it pulls electron density away, dispersing the negative charge on the carboxylate ion, thus stabilising it. This increases acidity (lowers pKa).