An ionic hydride of an alkali metal has significant covalent character and is almost unreactive towards oxygen and chlorine . This is used in the synthesisi of other useful hydrides. Write the formula of this is used in the synthesis of other hydrides. Write the formula of this hydride. Write its reaction with `Al_(2)Cl_(6)`.

Explanation

To solve the problem, we need to identify the ionic hydride of an alkali metal that has significant covalent character and is unreactive towards oxygen and chlorine. Then, we will write its reaction with Al₂Cl₆.

### Step 1: Identify the Ionic Hydride
- **Analysis**: The question states that the hydride is an ionic hydride of an alkali metal with significant covalent character. Among the alkali metals (Li, Na, K, Rb, Cs), lithium (Li) has the smallest cation size. According to Fajan's rules, smaller cations tend to have more covalent character when forming compounds.
- **Conclusion**: Therefore, the ionic hydride we are looking for is Lithium Hydride (LiH).

### Step 2: Write the Reaction with Al₂Cl₆
- **Reaction**: Lithium hydride reacts with aluminum chloride (Al₂Cl₆) to form lithium aluminum hydride (LiAlH₄) and lithium chloride (LiCl).
- **Balanced Equation**: The balanced chemical equation for the reaction is:
\[ 8 \text{LiH} + \text{Al}_2\text{Cl}_6 \rightarrow 2 \text{LiAlH}_4 + 6 \text{LiCl} \]

### Final Answer
- The formula of the hydride is **LiH** (Lithium Hydride).
- The reaction with Al₂Cl₆ is:
\[ 8 \text{LiH} + \text{Al}_2\text{Cl}_6 \rightarrow 2 \text{LiAlH}_4 + 6 \text{LiCl} \]