How many moles of `H_(2)O` are liberated when one mole hydrated `MgCl_(2)` is heated?

Options

A. 6
B. 5
C. 4
D. 3

Explanation

To determine how many moles of \( H_2O \) are liberated when one mole of hydrated \( MgCl_2 \) is heated, we can follow these steps:

### Step 1: Identify the formula of hydrated \( MgCl_2 \)

The hydrated form of magnesium chloride is \( MgCl_2 \cdot 6H_2O \). This indicates that one mole of \( MgCl_2 \) is associated with six moles of water.

### Step 2: Write the decomposition reaction

When \( MgCl_2 \cdot 6H_2O \) is heated, it decomposes into magnesium oxide (\( MgO \)), hydrochloric acid (\( HCl \)), and water (\( H_2O \)). The balanced chemical equation for this reaction is:

\[ MgCl_2 \cdot 6H_2O \rightarrow MgO + 2HCl + 5H_2O \]

### Step 3: Analyze the products

From the balanced equation, we can see that when one mole of \( MgCl_2 \cdot 6H_2O \) is heated, it produces:

- 1 mole of \( MgO \)
- 2 moles of \( HCl \)
- 5 moles of \( H_2O \)

### Step 4: Determine the moles of \( H_2O \) produced

Since we started with one mole of hydrated \( MgCl_2 \), the reaction produces 5 moles of water. Therefore, when one mole of hydrated \( MgCl_2 \) is heated, it liberates 5 moles of \( H_2O \).

### Final Answer

The number of moles of \( H_2O \) liberated when one mole of hydrated \( MgCl_2 \) is heated is **5 moles**.

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