Formic acid and Acetaldehyde can be distinguish by

Options

A. `I_(2)+NaOH`
B. Tollen's reagent
C. Fehling reagent
D. `2,4`-DNP test

Answer

To distinguish between formic acid (HCOOH) and acetaldehyde (CH3CHO), we can use Tollens' reagent. Here’s the step-by-step solution:

### Step 1: Understand the Compounds
- **Formic Acid (HCOOH)**: A carboxylic acid that acts as a reducing agent.
- **Acetaldehyde (CH3CHO)**: An aldehyde that can also act as a reducing agent but is less reactive than formic acid.

**Hint**: Identify the functional groups in each compound to understand their reactivity.

### Step 2: Identify the Reagent
- **Tollens' Reagent**: This is a solution of silver nitrate (AgNO3) in ammonia (NH3) and is used to test for aldehydes. It can oxidize aldehydes to carboxylic acids while being reduced to metallic silver.

**Hint**: Recall that Tollens' reagent is specifically used for detecting aldehydes.

### Step 3: Perform the Test
- When formic acid is treated with Tollens' reagent, it reduces the silver ions (Ag+) to metallic silver (Ag), resulting in a silver mirror on the test tube.
- Reaction:
\[ \text{HCOOH} + 2 \text{Ag}^+ + 2 \text{OH}^- \rightarrow 2 \text{Ag} + \text{CO}_2 + 2 \text{H}_2\text{O} \]

**Hint**: Remember that the formation of a silver mirror indicates a positive test for reducing agents.

### Step 4: Compare with Acetaldehyde
- When acetaldehyde is treated with Tollens' reagent, it does not produce a silver mirror because it is less reactive than formic acid.
- Therefore, no reaction occurs with acetaldehyde.

**Hint**: Consider the reactivity of aldehydes versus carboxylic acids when using Tollens' reagent.

### Conclusion
- Formic acid can be distinguished from acetaldehyde using Tollens' reagent because formic acid reduces the reagent to produce a silver mirror, while acetaldehyde does not react.

**Final Answer**: Formic acid and acetaldehyde can be distinguished by using **Tollens' reagent** (Option B).