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

Answer

To determine how many moles of water (H₂O) are liberated when one mole of hydrated magnesium chloride (MgCl₂·6H₂O) is heated, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Hydrated Form**:
The hydrated form of magnesium chloride is represented as MgCl₂·6H₂O. This indicates that each formula unit of magnesium chloride is associated with 6 water molecules.

2. **Write the Decomposition Reaction**:
When hydrated magnesium chloride is heated, it decomposes. The balanced chemical equation for the decomposition of MgCl₂·6H₂O can be written as:
\[ \text{MgCl}_2 \cdot 6\text{H}_2\text{O} \rightarrow \text{MgO} + 2\text{HCl} + 5\text{H}_2\text{O} \]

3. **Analyze the Products**:
From the balanced equation, we can see that for every 1 mole of hydrated magnesium chloride that decomposes, 5 moles of water (H₂O) are produced.

4. **Conclusion**:
Therefore, when one mole of hydrated magnesium chloride (MgCl₂·6H₂O) is heated, it liberates 5 moles of water (H₂O).

### Final Answer:
5 moles of H₂O are liberated when one mole of hydrated MgCl₂ is heated.

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