Molar Mass of Iron(III) oxide
Fe2O3 — 159.687 g/mol, worked out element by element.
Molar mass of Iron(III) oxide, Fe₂O₃
159.687 g/mol
Molecular weight 159.687 · 5 atoms per formula unit
Also known as: fe2o3, ferric oxide, rust, hematite.
Rust, and the ore blast furnaces reduce; the standard empirical-formula worked example.
How 159.687 g/mol is worked out
| Element | Atoms | Atomic mass | Mass | % of total |
|---|---|---|---|---|
| Iron | 2 | 55.845 | 111.690 | 69.94% |
| Oxygen | 3 | 15.999 | 47.997 | 30.06% |
| Total | 5 | 159.687 | 100% |
M = 2 × 55.845 + 3 × 15.999 = 159.687 g/mol
Grams to moles for Iron(III) oxide
| Mass | Moles | Formula units |
|---|---|---|
| 1 g | 0.0063 mol | 3.771 × 10^21 |
| 10 g | 0.0626 mol | 3.771 × 10^22 |
| 25 g | 0.1566 mol | 9.428 × 10^22 |
| 50 g | 0.3131 mol | 1.886 × 10^23 |
| 100 g | 0.6262 mol | 3.771 × 10^23 |
| 250 g | 1.5656 mol | 9.428 × 10^23 |
| 159.687 g | 1 mol | 6.022 × 10^23 |
For any other amount, use the molar mass calculator, or the molarity calculator to make up a solution of a given concentration.
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Frequently Asked Questions
What is the molar mass of Iron(III) oxide?
The molar mass of Iron(III) oxide (Fe2O3) is 159.687 g/mol. That is the sum of the standard atomic weights of all 5 atoms in one formula unit: 2 × 55.845 + 3 × 15.999 = 159.687.
What is the molecular weight of Iron(III) oxide?
159.687 — the same number as the molar mass, but as a dimensionless ratio rather than in g/mol. The two terms describe the same arithmetic, so a molecular weight of 159.69 and a molar mass of 159.69 g/mol are the same answer.
How many moles are in 100 g of Iron(III) oxide?
100 ÷ 159.687 = 0.6262 mol. To convert any mass to moles, divide by the molar mass; to go the other way, multiply.
What is the percent composition of Iron(III) oxide?
By mass, Iron(III) oxide is 69.94% iron, 30.06% oxygen. Each element's share is its total mass in the formula divided by 159.687.
How many atoms are in one formula unit of Iron(III) oxide?
5: 2 iron, 3 oxygen. One mole contains 6.02214076 × 10²³ formula units, so a mole of Iron(III) oxide contains 5 × 6.022 × 10²³ atoms in total.