See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Identifying the Weakest Acid **Step 1: Understand acid strength factors** Acid strength depends on the stability of the conjugate base formed after proton release. A more stable conjugate base means a weaker acid (lower $K_a$). **Step 2: Analyze each conjugate base** - **(A)** $CH_3COOH \rightarrow CH_3COO^-$ (acetate ion) - Negative charge on oxygen, stabilized by inductive effects - **(B)** $CH_3CO_2OH$ (peroxy acid) - Loses $H^+$ from O-H group: $CH_3CO_2O^-$ - Charge placed on oxygen *next to* electron-withdrawing $C=O$ group - Oxygen atoms are less electronegative than carbon, making the conjugate base highly unstable - **(C)** $ClCH_2COOH \rightarrow ClCH_2COO^-$ - Cl (electron-withdrawing) stabilizes the conjugate base - Makes this acid **stronger** than (A) - **(D)** $CH_3CH_2COOH \rightarrow CH_3CH_2COO^-$ (propionate ion) - Similar to (A), but slightly weaker due to less resonance stabilization **Step 3: Compare** Option (B) forms the most unstable conjugate base ($CH_3CO_2O^-$) because the negative charge sits on a less electronegative oxygen atom with minimal stabilization. **Answer: (B)** — The peroxy acid is the weakest because its conjugate base is highly destabilized.