Washing soda has the formula `Na_(2) CO_(2).10H_(2)O`. What is mass of anhydrous sodium carbonate left when all the water of crystallisation is expelled by heating 57.2 g of washing soda?

Explanation

To solve the problem, we need to find out how much anhydrous sodium carbonate (Na₂CO₃) is left after heating 57.2 g of washing soda (Na₂CO₃·10H₂O) to expel all the water of crystallization.

### Step-by-Step Solution:

1. **Determine the Molar Mass of Washing Soda (Na₂CO₃·10H₂O)**:
- Sodium (Na): 2 atoms × 23 g/mol = 46 g/mol
- Carbon (C): 1 atom × 12 g/mol = 12 g/mol
- Oxygen (O) in Na₂CO₃: 3 atoms × 16 g/mol = 48 g/mol
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