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Question
The percentage composition of sodium phosphate, as determined by analysis is : 42.1% Na, 18.9% P, 39% of O. Find the empirical formula of the compound.
[H =1, N =14, Na = 23, P = 31, Cl = 35.5, Pt = 195]
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Solution
| Element | Atomic mass | Percentage | Relative ratio of moles | Simplest mole ratio | Whole number ratio |
| Na | 23 | 42.1 | 42.1/23 = 1.8 | 1.8/0.6 =3 | 3 |
| P | 31 | 18.9 | 18.9/31 = 0.6 | 0.6/0.6 = 1 |
1 |
| O | 16 | 39 |
39/16 |
2.4/0.6 = 4 | 4 |
Empirical formula = Na3PO4.
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