How many of these compounds are more acidic than phenol here.
Formic acid, Benzoic acid, Picric acid, Ethanol, Water, Ortho - nitrophenol, Ortho - cresol, para - nitrophenol, para - cresol

Answer

To determine how many of the given compounds are more acidic than phenol, we will analyze each compound based on its structure and the stability of its conjugate base.

### Step-by-Step Solution:

1. **Identify the acidity of phenol**:
- Phenol (C6H5OH) has a pKa of about 10. This serves as our reference point for comparing the acidity of other compounds.

2. **Analyze Formic Acid (HCOOH)**:
- Formic acid is a carboxylic acid. Carboxylic acids are generally more acidic than phenol due to the resonance stabilization of their conjugate base (formate ion).
- **Conclusion**: More acidic than phenol.

3. **Analyze Benzoic Acid (C6H5COOH)**:
- Similar to formic acid, benzoic acid is also a carboxylic acid. Its conjugate base (benzoate ion) is stabilized by resonance with the aromatic ring.
- **Conclusion**: More acidic than phenol.

4. **Analyze Picric Acid (C6H2(NO2)3OH)**:
- Picric acid has three nitro groups which are strong electron-withdrawing groups. This significantly stabilizes the conjugate base (picrate ion) through resonance and inductive effects.
- **Conclusion**: More acidic than phenol.

5. **Analyze Ethanol (C2H5OH)**:
- Ethanol is an alcohol and has a pKa of about 16, which is much higher than that of phenol. It does not have significant resonance stabilization for its conjugate base.
- **Conclusion**: Not more acidic than phenol.

6. **Analyze Water (H2O)**:
- Water has a pKa of about 15.7, which is also higher than phenol. It is not more acidic than phenol.
- **Conclusion**: Not more acidic than phenol.

7. **Analyze Ortho-Nitrophenol (C6H4(NO2)OH)**:
- The nitro group in ortho position has a strong -M (mesomeric) effect, which stabilizes the conjugate base through resonance. This makes ortho-nitrophenol more acidic than phenol.
- **Conclusion**: More acidic than phenol.

8. **Analyze Ortho-Cresol (C6H4(CH3)OH)**:
- The methyl group is an electron-donating group (+I effect), which destabilizes the conjugate base, making ortho-cresol less acidic than phenol.
- **Conclusion**: Not more acidic than phenol.

9. **Analyze Para-Nitrophenol (C6H4(NO2)OH)**:
- Similar to ortho-nitrophenol, the para-nitro group also stabilizes the conjugate base through resonance, making it more acidic than phenol.
- **Conclusion**: More acidic than phenol.

10. **Analyze Para-Cresol (C6H4(CH3)OH)**:
- Like ortho-cresol, the methyl group in para-cresol also destabilizes the conjugate base due to its +I effect, making para-cresol less acidic than phenol.
- **Conclusion**: Not more acidic than phenol.

### Summary of Acidity Comparison:
- **More acidic than phenol**: Formic acid, Benzoic acid, Picric acid, Ortho-nitrophenol, Para-nitrophenol.
- **Not more acidic than phenol**: Ethanol, Water, Ortho-cresol, Para-cresol.

### Final Answer:
**5 compounds are more acidic than phenol.**

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