There is 20.30 g sample of a compound containing phosphorus and oxygen and 8.87 g of it is phosphorus. What is the empirical formula of compound

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justaguide eNotes educator| Certified Educator

A sample of the compound with mass 20.3 g has 8.87 g of phosphorus and the rest is oxygen as the compound is made up of oxygen and phosphorus. The mass of oxygen is 20.3 - 8.87 = 11.43 g

The molar mass of oxygen is `15.999 ~~ 16` and that of phosphorus is `30.973762 ~~ 31` . The ratio of oxygen to phosphorus atoms in the compound is `(11.43/16)/(8.87/31) ~~ 2.5`

This gives the number of oxygen atoms in the compound equal to 2.5 times the number of phosphorus atoms. Expressing this as a ratio of whole numbers, the ratio of the number of phosphorus atoms to the number of oxygen atoms is 2:5. The resulting empirical formula of the compound is `P_2O_5`