Formic acid is more acidic than

Options

A. Benzoic acid
B. Acetic acid
C. Phenol
D. Benzene sulphoric acid

Answer

To determine why formic acid is more acidic than the given compounds, we can analyze the structures and the factors affecting acidity.

### Step 1: Understanding Acidity
Acidity in organic compounds is primarily determined by the stability of the conjugate base formed after deprotonation. The more stable the conjugate base, the stronger the acid.

### Step 2: Analyzing Formic Acid
Formic acid (HCOOH) is a carboxylic acid. When it donates a proton (H⁺), it forms the formate ion (HCOO⁻). The negative charge on the formate ion is delocalized over the two oxygen atoms, which stabilizes the ion.

### Step 3: Comparing with Acetic Acid
Acetic acid (CH₃COOH) also forms a carboxylate ion (CH₃COO⁻) upon deprotonation. However, the presence of the methyl group (CH₃) in acetic acid is an electron-donating group. This donation of electron density destabilizes the conjugate base compared to the formate ion, making acetic acid less acidic than formic acid.

### Step 4: Comparing with Benzoic Acid
Benzoic acid (C₆H₅COOH) has a phenyl group (C₆H₅) attached to the carboxylic acid. While the phenyl group can stabilize the conjugate base through resonance, it is not as effective as the stabilization seen in formate ion. The resonance in benzoate ion (C₆H₅COO⁻) does not provide as much stabilization as the two resonance structures in formate ion.

### Step 5: Comparing with Phenol
Phenol (C₆H₅OH) is an alcohol. When phenol loses a proton, it forms the phenoxide ion (C₆H₅O⁻). The phenoxide ion is less stable than the formate ion because the negative charge is localized on the oxygen atom without the benefit of additional resonance structures that can stabilize it as effectively as the carboxylate ions.

### Conclusion
Based on the analysis, formic acid is more acidic than acetic acid, benzoic acid, and phenol due to the stability of its conjugate base, the formate ion.

### Final Answer
Formic acid is more acidic than acetic acid, benzoic acid, and phenol.

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