Answer:
The molar mass of Fe2O3 is 92 g/mol. We can use this information to find the molecular formula by calculating the empirical formula and then determining the molecular formula using the molar mass.
First, we need to find the empirical formula. To do this, we can assume that we have 100 grams of Fe2O3. We can then find the number of moles of each element in the compound:
Fe: (2 mol Fe / 1 mol Fe2O3) x (55.85 g Fe / 1 mol Fe) = 111.7 g Fe
O: (3 mol O / 1 mol Fe2O3) x (16.00 g O / 1 mol O) = 48.00 g O
Next, we need to find the smallest whole number ratio of Fe to O in the compound. We can divide the number of moles of each element by the smaller of the two:
Fe: 111.7 g / 55.85 g/mol = 1.999 mol
O: 48.00 g / 16.00 g/mol = 3.00 mol
Dividing both by the smaller number of moles (1.999 mol), we get:
Fe: 1.999 / 1.999 = 1
O: 3.00 / 1.999 = 1.501
Rounding to the nearest whole number, we get the empirical formula: Fe2O3.
To find the molecular formula, we need to determine the number of Fe2O3 units in one molecule. We can do this by dividing the molar mass of Fe2O3 (92 g/mol) by the empirical formula mass (2x55.85 + 3x16.00 = 159.70 g/mol):
Molecular formula mass = 92 g/mol / 159.70 g/mol = 0.576
Multiplying the empirical formula by 0.576, we get: Fe1.152O1.728
Rounding to the nearest whole number, the molecular formula of the compound is Fe2O3.