What percentage of water is found in `Na_(2)S,9H_(2)O`?

Explanation

To find the percentage of water in the compound \( \text{Na}_2\text{S} \cdot 9\text{H}_2\text{O} \), we will follow these steps:

### Step 1: Determine the molar mass of water (H₂O).
The molar mass of water (H₂O) can be calculated as follows:
- Hydrogen (H) has an atomic mass of approximately 1 g/mol. Since there are 2 hydrogen atoms in water, the total mass from hydrogen is \( 2 \times 1 = 2 \) g/mol.
- Oxygen (O) has an atomic mass of approximately 16 g/mol.
- Therefore, the molar mass of water (H₂O) is:
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