Increasing order of Lewis acid strength `AICI_(3)`,`GaCl_(3)` ,`InCl_(3)`

Options

A. `Iltlllt III`
B. `IIIltlllt I`
C. `IIltllt III`
D. ` IIIltllt II`

Answer

To determine the increasing order of Lewis acid strength among AlCl₃, GaCl₃, and InCl₃, we need to analyze the electron deficiency of each compound. Lewis acids are electron pair acceptors, and their strength is influenced by their ability to accept electrons, which is related to their electron deficiency.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have three compounds to consider: AlCl₃ (Aluminum Chloride), GaCl₃ (Gallium Chloride), and InCl₃ (Indium Chloride).

2. **Understand Lewis Acids**: Lewis acids are substances that can accept an electron pair. The more electron-deficient a compound is, the stronger it acts as a Lewis acid.

3. **Analyze Electron Deficiency**:
- **AlCl₃**: Aluminum has a smaller atomic size and a higher charge density compared to Ga and In. It has a significant electron deficiency due to its empty p-orbitals and can readily accept electrons.
- **GaCl₃**: Gallium is larger than aluminum, and its electron deficiency is less than that of AlCl₃ because of increased orbital overlap (4p with 3p).
- **InCl₃**: Indium is larger than gallium, and its electron deficiency is the least among the three due to even greater orbital overlap (5p with 3p), which stabilizes the electron cloud.

4. **Determine the Order of Electron Deficiency**:
- AlCl₃ > GaCl₃ > InCl₃ in terms of electron deficiency.
- This means AlCl₃ is the most electron deficient and thus the strongest Lewis acid, while InCl₃ is the least electron deficient and the weakest Lewis acid.

5. **Write the Increasing Order of Lewis Acid Strength**:
- Since we need the increasing order of Lewis acid strength, we can summarize it as:
- InCl₃ < GaCl₃ < AlCl₃

### Final Answer:
The increasing order of Lewis acid strength is:
**InCl₃ < GaCl₃ < AlCl₃**