---
title: "A student compares the acid ionization constants ( \\(K_a\\)) of four carboxylic acids: fluoroacetic acid (\\(\\text{CH}_2\\text{FCOOH}\\)), chloroacetic acid (\\(\\text{CH}_2\\text{ClCOOH}\\)), bromoacetic acid (\\(\\text{CH}_2\\text{BrCOOH}\\)), and acetic acid (\\(\\text{CH}_3\\text{COOH}\\)). Which of the following lists the acids in order of decreasing acid strength (from strongest to weakest) and provides the correct explanation?"
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url: "https://nerd-notes.com/ubq/121472/"
date_modified: "2026-08-23T05:04:45+00:00"
---

# A student compares the acid ionization constants (
\(K_a\)) of four carboxylic acids: fluoroacetic acid (\(\text{CH}_2\text{FCOOH}\)), chloroacetic acid (\(\text{CH}_2\text{ClCOOH}\)), bromoacetic acid (\(\text{CH}_2\text{BrCOOH}\)), and acetic acid (\(\text{CH}_3\text{COOH}\)). Which of the following lists the acids in order of decreasing acid strength (from strongest to weakest) and provides the correct explanation?

A student compares the acid ionization constants (
\(K_a\)) of four carboxylic acids: fluoroacetic acid (\(\text{CH}_2\text{FCOOH}\)), chloroacetic acid (\(\text{CH}_2\text{ClCOOH}\)), bromoacetic acid (\(\text{CH}_2\text{BrCOOH}\)), and acetic acid (\(\text{CH}_3\text{COOH}\)). Which of the following lists the acids in order of decreasing acid strength (from strongest to weakest) and provides the correct explanation?

- **A.** \(\text{CH}_2\text{FCOOH} > \text{CH}_2\text{ClCOOH} > \text{CH}_2\text{BrCOOH} > \text{CH}_3\text{COOH}\), because fluorine has the greatest electronegativity, producing the strongest inductive electron withdrawal that stabilizes the conjugate base.
- **B.** \(\text{CH}_3\text{COOH} > \text{CH}_2\text{BrCOOH} > \text{CH}_2\text{ClCOOH} > \text{CH}_2\text{FCOOH}\), because halogen substituents draw electron density toward the carboxyl group, strengthening the \(\text{O}-\text{H}\) bond and inhibiting proton release.
- **C.** \(\text{CH}_2\text{FCOOH} > \text{CH}_2\text{ClCOOH} > \text{CH}_2\text{BrCOOH} > \text{CH}_3\text{COOH}\), because the smaller fluorine atom forms stronger intermolecular hydrogen bonds with water, pulling the acidic proton into solution.
- **D.** \(\text{CH}_2\text{BrCOOH} > \text{CH}_2\text{ClCOOH} > \text{CH}_2\text{FCOOH} > \text{CH}_3\text{COOH}\), because bromine has the largest atomic radius and greatest polarizability, which delocalizes the negative charge on the carboxylate group most effectively.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/121472/*