One can distinguish between `HCOOH` and `CH_3 COOH` with :

Options

A. `NaHCO_(3)`
B. tollens reagent
C. fehling's solution
D. None of these

Answer

To distinguish between HCOOH (formic acid) and CH3COOH (acetic acid), we can use specific reagents that will react differently with these two acids. Here’s a step-by-step solution:

### Step 1: Understanding the Acids
- **HCOOH (Formic Acid)**: A simple carboxylic acid that can be oxidized easily.
- **CH3COOH (Acetic Acid)**: A carboxylic acid that is less easily oxidized compared to formic acid.

### Step 2: Testing with Sodium Bicarbonate (NaHCO3)
- When both acids react with sodium bicarbonate, they produce carbon dioxide (CO2) and a corresponding sodium salt.
- **Reaction with HCOOH**:
\[ \text{HCOOH} + \text{NaHCO}_3 \rightarrow \text{HCOONa} + \text{CO}_2 + \text{H}_2\text{O} \]
- **Reaction with CH3COOH**:
\[ \text{CH}_3\text{COOH} + \text{NaHCO}_3 \rightarrow \text{CH}_3\text{COONa} + \text{CO}_2 + \text{H}_2\text{O} \]
- **Conclusion**: Both reactions produce CO2, so this test cannot distinguish between the two acids.

### Step 3: Testing with Tollens Reagent
- **Tollens Reagent**: This reagent is used to test for aldehydes and some carboxylic acids.
- **Reaction with HCOOH**:
\[ \text{HCOOH} + 2 \text{Ag(NH}_3)_2^+ + 2 \text{OH}^- \rightarrow 2 \text{Ag} + \text{CO}_2 + 2 \text{H}_2\text{O} + 4 \text{NH}_3 \]
- This reaction produces a silver mirror, indicating a positive test.
- **Reaction with CH3COOH**:
- Acetic acid does not react with Tollens reagent and does not produce a silver mirror.
- **Conclusion**: Tollens reagent can distinguish between formic acid (positive test) and acetic acid (negative test).

### Step 4: Testing with Fehling's Solution
- **Fehling's Solution**: This is used to test for reducing sugars and some carboxylic acids.
- **Reaction with HCOOH**:
\[ \text{HCOOH} + 2 \text{Cu}^{2+} + 4 \text{OH}^- \rightarrow \text{Cu}_2\text{O} + \text{CO}_2 + 3 \text{H}_2\text{O} \]
- This reaction produces a red precipitate of Cu2O, indicating a positive test.
- **Reaction with CH3COOH**:
- Acetic acid does not produce a red precipitate with Fehling's solution.
- **Conclusion**: Fehling's solution can also distinguish between formic acid (positive test) and acetic acid (negative test).

### Final Conclusion
To distinguish between HCOOH and CH3COOH, we can use either Tollens reagent or Fehling's solution. Both tests will yield a positive result for formic acid and a negative result for acetic acid.

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