Which of the following is the strongest base?

Options

A. `C_(2)H_(5)^(-)`
B. `C_(2)H_(5)COO`
C. `C_(2)H_(5)O^(-)`
D. `OH^(-)`

Explanation

To determine which of the given options is the strongest base, we need to analyze the conjugate acids formed when each base reacts with a proton (H⁺). The base with the weakest conjugate acid will be the strongest base.

### Step-by-Step Solution:

1. **Identify the Bases and Their Conjugate Acids:**
- **C₂H₅⁻ (Ethyl anion)**: When it reacts with H⁺, it forms C₂H₆ (Ethane).
- **C₂H₅COO⁻ (Ethanoate ion)**: When it reacts with H⁺, it forms C₂H₅COOH (Ethanoic acid).
- **C₂H₅O⁻ (Ethoxide ion)**: When it reacts with H⁺, it forms C₂H₅OH (Ethanol).
- **OH⁻ (Hydroxide ion)**: When it reacts with H⁺, it forms H₂O (Water).

2. **Analyze the Conjugate Acids:**
- **C₂H₆ (Ethane)**: This is a saturated hydrocarbon and does not easily donate H⁺, making it a weak acid.
- **C₂H₅COOH (Ethanoic acid)**: This is a weak acid that can donate H⁺.
- **C₂H₅OH (Ethanol)**: This is also a weak acid that can donate H⁺.
- **H₂O (Water)**: Water can act as both an acid and a base, but it is a weak acid.

3. **Determine the Strength of the Conjugate Acids:**
- Among the conjugate acids, C₂H₆ (Ethane) is the weakest acid because it does not readily donate H⁺ due to its stable covalent bonds.
- The other acids (C₂H₅COOH and C₂H₅OH) are stronger acids compared to ethane.

4. **Conclude the Strongest Base:**
- Since C₂H₅⁻ (Ethyl anion) has the weakest conjugate acid (C₂H₆), it is the strongest base among the options provided.

### Final Answer:
**C₂H₅⁻ (Ethyl anion) is the strongest base.**

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