Which is weakest acid in the following?

Options

A. `CH_(2)OH`
B. `(CH_(3))_(2)CHOH`
C. `CH_(3)CH_(2)OH`
D. `(CH_(3))_(3)COH`

Answer

To determine which is the weakest acid among the given options, we need to analyze the stability of the conjugate bases formed when each acid donates a proton (H⁺). The weaker the acid, the less stable its conjugate base will be.

### Step-by-Step Solution:

1. **Identify the Acids**:
Let's assume we have four acids to compare:
- Acid A: CH₃OH (Methanol)
- Acid B: CH₃CH₂OH (Ethanol)
- Acid C: (CH₃)₂CHOH (Isopropanol)
- Acid D: (CH₃)₃COH (Tert-butanol)

2. **Understand Acid Strength**:
The strength of an acid is determined by its ability to donate a proton (H⁺). When an acid donates a proton, it forms a conjugate base (A⁻). The stability of this conjugate base is crucial in determining the strength of the acid. A more stable conjugate base corresponds to a stronger acid.

3. **Analyze Conjugate Bases**:
- For CH₃OH, the conjugate base is CH₃O⁻.
- For CH₃CH₂OH, the conjugate base is CH₃CH₂O⁻.
- For (CH₃)₂CHOH, the conjugate base is (CH₃)₂CHO⁻.
- For (CH₃)₃COH, the conjugate base is (CH₃)₃C⁻.

4. **Stability of Conjugate Bases**:
- The stability of the conjugate base can be influenced by the inductive effect of alkyl groups. Alkyl groups are electron-donating, which can destabilize the negative charge on the conjugate base.
- CH₃O⁻ has one alkyl group (methyl).
- CH₃CH₂O⁻ has two alkyl groups (ethyl).
- (CH₃)₂CHO⁻ has three alkyl groups (isopropyl).
- (CH₃)₃C⁻ has four alkyl groups (tert-butyl).

5. **Determine Weakest Acid**:
- The more alkyl groups attached to the conjugate base, the less stable it becomes due to increased electron density. Therefore, the acid with the least stable conjugate base will be the weakest acid.
- Among the conjugate bases, (CH₃)₃C⁻ is the least stable due to the high electron-donating effect of the four alkyl groups.

6. **Conclusion**:
- Therefore, the weakest acid among the given options is **(CH₃)₃COH (Tert-butanol)**.

### Final Answer:
The weakest acid is **(CH₃)₃COH (Tert-butanol)**.

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