Alkynes are .......... acidic than alkenes.

Answer

To determine whether alkynes are more acidic than alkenes, we need to analyze the stability of the anions formed when a hydrogen ion (H⁺) is removed from each type of hydrocarbon.

### Step-by-Step Solution:

1. **Identify the Hydrocarbons**:
- Consider an alkyne, for example, but-1-yne (CH₃-C≡C-H).
- Consider an alkene, for example, but-1-ene (CH₃-CH=CH₂).

2. **Remove a Proton (H⁺)**:
- For the alkyne, removing H⁺ gives us the anion: CH₃-C≡C⁻.
- For the alkene, removing H⁺ gives us the anion: CH₃-CH=CH⁻.

3. **Determine Hybridization**:
- In but-1-yne, the carbon atom bonded to the hydrogen (from which H⁺ is removed) is sp hybridized.
- In but-1-ene, the carbon atom bonded to the hydrogen is sp² hybridized.

4. **Analyze S Character**:
- The sp hybridized carbon has 50% s character.
- The sp² hybridized carbon has 33.3% s character.

5. **Relate S Character to Electronegativity**:
- Higher s character means greater electronegativity. Therefore, the sp hybridized carbon (in alkynes) is more electronegative than the sp² hybridized carbon (in alkenes).
- This increased electronegativity allows the sp hybridized carbon to better stabilize the negative charge of the anion formed after the removal of H⁺.

6. **Conclude Acidity**:
- Since the anion formed from the alkyne (CH₃-C≡C⁻) is more stable due to the higher electronegativity and s character, alkynes are more acidic than alkenes.

### Final Answer:
Alkynes are **more acidic** than alkenes.

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