The distinguishing test between methanoic acid and ethanoic acid is :

Options

A. litmus test
B. sodium bicarbonate test
C. Tollen's test
D. esterification test

Answer

To distinguish between methanoic acid (formic acid) and ethanoic acid (acetic acid), we can perform a specific test that takes advantage of the unique functional groups present in these compounds. Here’s a step-by-step solution:

### Step 1: Identify the Structures
- **Methanoic Acid (Formic Acid)**: Its structure is HCOOH, which contains one carbon atom and a carboxylic acid group.
- **Ethanoic Acid (Acetic Acid)**: Its structure is CH3COOH, which contains two carbon atoms and a carboxylic acid group.

### Step 2: Recognize Functional Groups
- Methanoic acid has both a carboxylic acid group and an aldehyde group (as it can be considered as the simplest carboxylic acid).
- Ethanoic acid has only a carboxylic acid group.

### Step 3: Perform the Tollen's Test
- The Tollen's test is a distinguishing test for aldehydes. When methanoic acid is treated with Tollen's reagent (ammoniacal silver nitrate), it will reduce the silver ions to metallic silver, forming a silver mirror.
- Ethanoic acid, lacking the aldehyde group, will not give a positive Tollen's test.

### Step 4: Conclusion
- Since methanoic acid gives a positive Tollen's test due to the presence of the aldehyde group, while ethanoic acid does not, we can distinguish between the two acids using this test.

### Final Answer
The distinguishing test between methanoic acid and ethanoic acid is the **Tollen's test**, which will yield a positive result for methanoic acid but not for ethanoic acid.

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