Which equilibrium can be described as an acid base reaction using the Lewis acid-base definition but not using the Bronsted-Lowery definition?

Options

A. ` 2NH_3+H_2SO_4 hArr 2NH_4^(+) +SO_4^(2-)`
B. ` NH_3+CH_3COOH hArr NH_4^(+) +CH_3COO^(-)`
C. ` H_2O + CH_3COOH hArr H_3O^(+) CH_3COO^(-)`
D. ` [Cu(H_2O )_4^(2+) +4NH_3 hArr [Cu(NH_3)_4]^(2+) +4H_2O`

Answer

To solve the question, we need to identify an equilibrium that can be classified as an acid-base reaction according to the Lewis definition but not according to the Bronsted-Lowry definition.

### Step-by-Step Solution:

1. **Understand the Definitions:**
- **Bronsted-Lowry Definition:** An acid is a substance that donates a proton (H⁺), and a base is a substance that accepts a proton.
- **Lewis Definition:** An acid is a substance that accepts a lone pair of electrons, and a base is a substance that donates a lone pair of electrons.

2. **Analyze the Options:**
- We need to evaluate each option to see if it fits the criteria of being a Lewis acid-base reaction but not a Bronsted-Lowry reaction.

3. **Option 1: NH₃ + H₂SO₄**
- NH₃ accepts a proton (H⁺) from H₂SO₄, making NH₃ a Bronsted base and H₂SO₄ a Bronsted acid. This reaction fits both definitions.

4. **Option 2: NH₃ + CH₃COOH**
- NH₃ accepts a proton from CH₃COOH, making NH₃ a Bronsted base and CH₃COOH a Bronsted acid. This reaction fits both definitions.

5. **Option 3: H₂O + CH₃COOH**
- H₂O accepts a proton from CH₃COOH, making H₂O a Bronsted base and CH₃COOH a Bronsted acid. This reaction fits both definitions.

6. **Option 4: Cu²⁺ + 4 NH₃**
- In this case, NH₃ donates a lone pair of electrons to Cu²⁺. Here, NH₃ acts as a Lewis base, and Cu²⁺ acts as a Lewis acid. There is no transfer of protons involved, which means it does not fit the Bronsted-Lowry definition.

7. **Conclusion:**
- The only reaction that can be classified as an acid-base reaction using the Lewis definition but not the Bronsted-Lowry definition is **Option 4: Cu²⁺ + 4 NH₃**.

### Final Answer:
**The equilibrium that can be described as an acid-base reaction using the Lewis acid-base definition but not using the Bronsted-Lowry definition is Option 4: Cu²⁺ + 4 NH₃.**