Final answer:
The empirical formula of a compound containing only iron and oxygen with 22.27% oxygen by mass is determined to be FeO, indicating a 1:1 molar ratio of iron to oxygen. Option A is correct.
Step-by-step explanation:
To determine the empirical formula of a compound that contains only iron and oxygen with 22.27% oxygen by mass, we first calculate the moles of each element in a 100 g sample, assuming we have 100 g of the compound. This simplifies the calculation since the percentages can be directly treated as grams. The molar mass of oxygen (O) is approximately 16 g/mol, and iron (Fe) has an approximate molar mass of 56 g/mol.
For oxygen: 22.27 g O × (1 mol O / 16 g O) = 1.392 mol O
For iron: (100 g - 22.27 g) Fe × (1 mol Fe / 56 g Fe) = 1.388 mol Fe
The ratio of iron to oxygen can be calculated by dividing the moles of each element by the smallest number of moles obtained:
1.388 mol Fe / 1.388 = 1
1.392 mol O / 1.388 ≈ 1
Even though these resulting numbers are very close to each other, they are not precise enough to suggest a 1:1 ratio directly. However, because the numbers are close to each other and considering that there must be whole numbers in the subscripts of an empirical formula, one can estimate that the empirical formula is FeO, which indicates a 1:1 ratio of iron to oxygen. Thus, the empirical formula of a compound that contains only iron and oxygen and is 22.27% oxygen is FeO (option A).
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