The mass of a piece of iron is 1.62 g. If the iron is exposed to oxygen under conditions in which oxygen combines with all of the iron to form pure oxide of iron, the final mass increased to 2.31 g.
Find the empirical formula.
2007-09-14 17:57:17 · 2 answers · asked by gurlygal 1 in Science & Mathematics ➔ Chemistry
Mass of oxygen gained = 2.31 - 1.62 = 0.69 g
1.62 g Fe / 55.8 g/mole = 0.029 mole Fe
0.69 g O / 16.0 g/mole = 0.043 mole O
0.043 / 0.029 = 1.48 ~ 1.5, so 3 moles of oxygen for two moles of iron. Empirical formula is Fe2O3.
2007-09-14 18:06:41 · answer #1 · answered by TheOnlyBeldin 7 · 0⤊ 0⤋
Divide the mass of iron weight by the atomic weight of iron to get moles. Now, take the increase in weight (due to oxygen) and divide by the g-atomic weight of oxygen to get moles of O.
Now, set the moles of iron=1, and scale-up the moles of O by the same factor.
2007-09-15 01:07:09 · answer #2 · answered by cattbarf 7 · 0⤊ 0⤋