Write the correct order of acidic strength of following compounds:
`(a)CH_(3)COOH" "(d)CH_(3)CH_(2)OH`
`(c )C_(6)H_(5)OH" "(d)C_(6)H_(5)SO_(3)H`

Answer

To determine the correct order of acidic strength for the given compounds, we need to analyze the stability of the anions formed after the loss of a proton (H⁺). The more stable the anion, the stronger the acid. Let's evaluate each compound step by step.

### Step 1: Identify the Compounds
The compounds given are:
- (a) CH₃COOH (Acetic Acid)
- (b) CH₃CH₂OH (Ethanol)
- (c) C₆H₅OH (Phenol)
- (d) C₆H₅SO₃H (Benzene Sulfonic Acid)

### Step 2: Analyze the Deprotonation of Each Compound
1. **Acetic Acid (CH₃COOH)**:
- Upon losing H⁺, it forms CH₃COO⁻ (acetate ion).
- The negative charge on the acetate ion is stabilized by resonance with the carbonyl group (C=O).
- Resonance structures allow the negative charge to be delocalized, enhancing stability.

2. **Ethanol (CH₃CH₂OH)**:
- Upon losing H⁺, it forms CH₃CH₂O⁻ (ethoxide ion).
- There is no resonance stabilization for the negative charge; it remains localized on the oxygen atom.
- Additionally, the alkyl group (methyl) has a +I effect, which increases electron density and destabilizes the anion.

3. **Phenol (C₆H₅OH)**:
- Upon losing H⁺, it forms C₆H₅O⁻ (phenoxide ion).
- The negative charge on the phenoxide ion is stabilized by resonance within the aromatic ring.
- This delocalization of the negative charge across the ring enhances stability.

4. **Benzene Sulfonic Acid (C₆H₅SO₃H)**:
- Upon losing H⁺, it forms C₆H₅SO₃⁻ (benzenesulfonate ion).
- The negative charge is highly stabilized by resonance with the sulfonyl group (S=O).
- This compound can delocalize the negative charge over multiple oxygen atoms, providing significant stability.

### Step 3: Compare the Stability of the Anions
- **Benzene Sulfonate Ion (C₆H₅SO₃⁻)**: Most stable due to resonance with three oxygen atoms.
- **Acetate Ion (CH₃COO⁻)**: Stable due to resonance with one carbonyl group.
- **Phenoxide Ion (C₆H₅O⁻)**: Stable due to resonance in the aromatic ring, but less stable than acetate.
- **Ethoxide Ion (CH₃CH₂O⁻)**: Least stable due to lack of resonance and destabilizing +I effect.

### Step 4: Determine the Order of Acidity
Based on the stability of the anions formed after deprotonation, we can arrange the compounds in order of increasing acidity:
1. **Ethanol (CH₃CH₂OH)** - least acidic
2. **Phenol (C₆H₅OH)**
3. **Acetic Acid (CH₃COOH)**
4. **Benzene Sulfonic Acid (C₆H₅SO₃H)** - most acidic

### Final Order of Acidity
The correct order of acidic strength is:
**C₆H₅SO₃H > CH₃COOH > C₆H₅OH > CH₃CH₂OH**