Molar Mass of Oxygen gas
O2 — 31.998 g/mol, worked out element by element.
Molar mass of Oxygen gas, O₂
31.998 g/mol
Molecular weight 31.998 · 2 atoms per formula unit
Also known as: o2, dioxygen.
Diatomic in every gas-phase equation — using 16 rather than 32 g/mol is the most common stoichiometry slip there is.
How 31.998 g/mol is worked out
| Element | Atoms | Atomic mass | Mass | % of total |
|---|---|---|---|---|
| Oxygen | 2 | 15.999 | 31.998 | 100.00% |
| Total | 2 | 31.998 | 100% |
M = 2 × 15.999 = 31.998 g/mol
Grams to moles for Oxygen gas
| Mass | Moles | Formula units |
|---|---|---|
| 1 g | 0.0313 mol | 1.882 × 10^22 |
| 10 g | 0.3125 mol | 1.882 × 10^23 |
| 25 g | 0.7813 mol | 4.705 × 10^23 |
| 50 g | 1.5626 mol | 9.410 × 10^23 |
| 100 g | 3.1252 mol | 1.882 × 10^24 |
| 250 g | 7.8130 mol | 4.705 × 10^24 |
| 31.998 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 Oxygen gas?
The molar mass of Oxygen gas (O2) is 31.998 g/mol. That is the sum of the standard atomic weights of all 2 atoms in one formula unit: 2 × 15.999 = 31.998.
What is the molecular weight of Oxygen gas?
31.998 — 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 32.00 and a molar mass of 32.00 g/mol are the same answer.
How many moles are in 100 g of Oxygen gas?
100 ÷ 31.998 = 3.1252 mol. To convert any mass to moles, divide by the molar mass; to go the other way, multiply.
What is the percent composition of Oxygen gas?
By mass, Oxygen gas is 100.00% oxygen. Each element's share is its total mass in the formula divided by 31.998.
How many atoms are in one formula unit of Oxygen gas?
2: 2 oxygen. One mole contains 6.02214076 × 10²³ formula units, so a mole of Oxygen gas contains 2 × 6.022 × 10²³ atoms in total.