In the reaction `LiH+AlH_(3) to LiAlH_(4), AlH_(3) and LiH` act as :

Options

A. Lewis acid and Lewis base
B. Lewis base and Lewis acid
C. Bronsted base and Bronsted acid
D. None of these

Answer

To determine the roles of LiH and AlH3 in the reaction to form LiAlH4, we can analyze the reaction step by step.

### Step 1: Understand the Reaction
The reaction given is:
\[ \text{LiH} + \text{AlH}_3 \rightarrow \text{LiAlH}_4 \]

### Step 2: Identify the Components
- **LiH (Lithium Hydride)**: This compound can donate a hydride ion (H⁻).
- **AlH3 (Aluminum Hydride)**: This compound can accept a hydride ion.

### Step 3: Analyze Electron Transfer
In the reaction:
- **LiH** donates a hydride ion (H⁻) to **AlH3**.
- **AlH3** accepts the hydride ion (H⁻) from **LiH**.

### Step 4: Define Lewis Acid and Lewis Base
- A **Lewis Acid** is a species that accepts an electron pair.
- A **Lewis Base** is a species that donates an electron pair.

### Step 5: Determine the Roles
From the analysis:
- **LiH** acts as a Lewis Base because it donates the hydride ion (H⁻).
- **AlH3** acts as a Lewis Acid because it accepts the hydride ion (H⁻).

### Conclusion
Thus, in the reaction \( \text{LiH} + \text{AlH}_3 \rightarrow \text{LiAlH}_4 \):
- **LiH is a Lewis Base**
- **AlH3 is a Lewis Acid**

The correct answer is: **Lewis acid and Lewis base**.

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