The correct order of increasing acidic strength is _____.

Options

A. Phenol< Ethanol < Chloroacetic acid < Acetic acid
B. Ethanol < phenol < Chloroacetic acid < acetic acid
C. Ethanol< phenol< acetic acid
< Chloroacetic acid
D. Chloroacetic acid < acetic acid < phenol < ethanol

Answer

To determine the correct order of increasing acidic strength among the given compounds (phenol, ethanol, acetic acid, and chloroacetic acid), we need to analyze the stability of their conjugate bases. The more stable the conjugate base, the stronger the acid.

### Step-by-Step Solution:

1. **Identify the Compounds:**
- The compounds we are comparing are:
- Phenol (C6H5OH)
- Ethanol (C2H5OH)
- Acetic Acid (CH3COOH)
- Chloroacetic Acid (CH2ClCOOH)

2. **Determine the Conjugate Bases:**
- When these acids donate a proton (H+), they form their respective conjugate bases:
- Phenol → C6H5O⁻
- Ethanol → C2H5O⁻
- Acetic Acid → CH3COO⁻
- Chloroacetic Acid → CH2ClCOO⁻

3. **Analyze Stability of Conjugate Bases:**
- The stability of the conjugate base is key to determining the acidity of the acid.
- **Phenol (C6H5O⁻):** The negative charge on oxygen can be delocalized into the aromatic ring, increasing stability.
- **Ethanol (C2H5O⁻):** The negative charge is localized on oxygen and is not stabilized by resonance, making it less stable than phenol.
- **Acetic Acid (CH3COO⁻):** The negative charge is delocalized between the two oxygen atoms, providing some stability.
- **Chloroacetic Acid (CH2ClCOO⁻):** The presence of the electron-withdrawing Cl group increases the stability of the conjugate base by reducing electron density on the negatively charged oxygen.

4. **Rank the Acids Based on Stability of Conjugate Bases:**
- Chloroacetic Acid (most stable conjugate base) > Acetic Acid > Phenol > Ethanol (least stable conjugate base).
- Therefore, the order of increasing acidic strength is:
- Ethanol < Phenol < Acetic Acid < Chloroacetic Acid.

5. **Final Answer:**
- The correct order of increasing acidic strength is:
- **Ethanol < Phenol < Acetic Acid < Chloroacetic Acid.**