Final answer:
The molecular formula for the compound with empirical formula P₂O₅ and a molar mass of 285±10 g/mol is P₄O₁₀.
Step-by-step explanation:
The empirical formula of a compound is a formula that represents the simplest whole number ratio of the elements present. To determine the molecular formula from the empirical formula, we need to know the molar mass of the compound. In this case, the compound has an empirical formula of P₂O₅ and a molar mass of 285±10 g/mol. The molar mass of the empirical formula P₂O₅ is 2*(31.0 g/mol) + 5*(16.0 g/mol) = 142.0 g/mol. Therefore, the molecular formula of the compound must be a multiple of the empirical formula. To find the multiple, we divide the molar mass of the compound (285 g/mol) by the molar mass of the empirical formula (142 g/mol). The result is approximately 2.0. This indicates that the molecular formula of the compound is twice the empirical formula. Therefore, the molecular formula of the compound is P₄O₁₀.