Sodium forms a crystalline ionic solid with dihdrogen . The solid is non-volatile and non-conducting in nature. It reacts violently with water to produce dihydrogen gas. Write the formula of this compound and its reaction with water. What will happen on electrolysis of the melt of this solid ?

Explanation

### Step-by-Step Solution:

1. **Identify the Compound**: Sodium (Na) reacts with dihydrogen (H₂) to form sodium hydride (NaH). This compound is an ionic solid that is crystalline in structure.

**Formula of the Compound**:
\[ \text{NaH} \]

2. **Reaction with Water**: Sodium hydride reacts violently with water, producing sodium hydroxide (NaOH) and dihydrogen gas (H₂). The balanced chemical equation for this reaction is:

\[ 2 \text{NaH} + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2 \]

3. **Electrolysis of the Melt**: When sodium hydride is melted and subjected to electrolysis, it dissociates into sodium ions (Na⁺) and hydride ions (H⁻). The reactions at the electrodes during electrolysis are as follows:

- At the **cathode** (negative electrode), sodium ions gain electrons to form sodium metal:
\[ \text{Na}^+ + e^- \rightarrow \text{Na} \]

- At the **anode** (positive electrode), hydride ions lose electrons to form dihydrogen gas:
\[ \text{H}^- \rightarrow \text{H}^+ + e^- \quad \text{(2H}^- \rightarrow \text{H}_2 + 2e^-) \]

Therefore, the overall reaction during electrolysis produces sodium metal at the cathode and dihydrogen gas at the anode.

### Summary of the Solution:
- **Formula of the Compound**: NaH
- **Reaction with Water**:
\[ 2 \text{NaH} + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2 \]
- **Electrolysis Products**: Sodium metal at the cathode and dihydrogen gas at the anode.

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