31 gof phosphorousreacted with oxygengas to form 71 gof a phosphorousoxide. what is the empirical formulaof the oxide

In this problem you would need to determine the mass of each element first. The mass of phosphorus is given which is 31 grams. The mass of oxygen is the difference between 71 grams and 31 since we know that the compound formed weighs 71 grams. Then determine the moles of each element. You would get 1.0009 moles for phosphorus and 2.5 moles for oxygen. You have to then multiply the moles to the lowest number that would give a whole number for each element. The empirical formula of the oxide is P2O5.