The molar mass of sodium nitrite, NaNO2, is 68.994769 g/mol. That single number is what connects a mass you can weigh to an amount of substance you can react: one mole is 68.99477 g, and a gram of it is 8.728e+21 formula units. The calculator turns any weighed mass into that count, and reports the amount in moles, millimoles and the mass of a single formula unit alongside it.
The figure comes from the formula. Sodium nitrite is 22.9898 (Na) + 14.007 (N) + 2 × 15.999 (O), which is 68.994769 g/mol, taking standard atomic weights, and every page here computes that sum rather than quoting it. Oxygen makes up the largest share of the mass: 2 of the 4 atoms in a formula unit are oxygen, and they account for 31.998 g of the 68.99477 g, or 46.38% by mass. The derivation table below breaks the whole molecule down element by element.
The numbers a bench actually uses sit at the millimole scale. One millimole of sodium nitrite is 68.9948 mg and one micromole is 68.9948 µg, so a balance reading to a milligram places you within 14.49 µmol. A single formula unit weighs 1.1457e-22 g, which is why the count in the gauge runs into the sextillions for any mass you can see.
The curing salt in bacon and ham, used at a fraction of a percent, and a corrosion inhibitor. Pink curing salt is 6.25% of it in sodium chloride. At 68.99477 g/mol it is heavier than 2 of the 34 salts covered here, and that ranking matters more than it looks: sodium chloride has a molar mass of 58.43977 g/mol, so a gram of it contains 18.1% more formula units than a gram of sodium nitrite. Weigh by mass and you are not weighing equal amounts of substance.
Two practical things move the result. Purity below 100% means the weighed mass overstates how much compound you have — at 98% assay, 1.3799 g of every 68.99477 g is not the compound — and any water picked up from the air does the same. Both are systematic, so they shift every solution made from that jar in the same direction.
The formula
m- The mass of sodium nitrite in grams
68.994769- The molar mass of sodium nitrite in g/mol, derived from its formula
N- The number of formula units that mass contains
How it works, step by step
- Enter a mass of sodium nitrite in grams.
- It is divided by the molar mass, 68.994769 g/mol, giving the amount in moles.
- That amount is multiplied by the Avogadro constant, 6.02214076 × 10²³ per mole, to give the number of formula units.
- The panel also reports the amount in moles and millimoles and the mass of one formula unit.
Worked examples
0.5 g of sodium nitrite as a molecule count
0.5 g divided by 68.99477 g/mol is 0.00724693 mol, and multiplying by the Avogadro constant gives 4.364e+21 formula units of sodium nitrite. The same mass is 7.2469 mmol, which is the figure a reaction is actually planned in.
5 g of sodium nitrite as a molecule count
5 g divided by 68.99477 g/mol is 0.0724693 mol, and multiplying by the Avogadro constant gives 4.364e+22 formula units of sodium nitrite. The same mass is 72.469 mmol, which is the figure a reaction is actually planned in.
50 g of sodium nitrite as a molecule count
50 g divided by 68.99477 g/mol is 0.724693 mol, and multiplying by the Avogadro constant gives 4.364e+23 formula units of sodium nitrite. The same mass is 724.69 mmol, which is the figure a reaction is actually planned in.
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Frequently asked questions
What is the molar mass of sodium nitrite (NaNO2)?
It is 68.994769 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 22.9898 (Na) + 14.007 (N) + 2 × 15.999 (O). One mole of sodium nitrite therefore weighs 68.99477 g, and a gram of it is 14.494 mmol.
What percentage of sodium nitrite is oxygen?
46.38% by mass. Each formula unit contains 2 oxygen atoms contributing 31.998 g of the 68.99477 g total, so 100 g of sodium nitrite contains 46.38 g of oxygen and a kilogram contains 463.77 g of it.
How many molecules are in one gram of sodium nitrite?
About 8.728e+21. One gram is 0.0144939 mol, and each mole contains 6.02214076 × 10²³ formula units by definition of the mole, so the count is that constant divided by 68.99477.
How much does a single molecule of sodium nitrite weigh?
1.1457e-22 g, which is 68.994769 daltons. It is the molar mass divided by the Avogadro constant, and the number in daltons is numerically the same as the molar mass in g/mol — that equivalence is what makes the mole convenient.
Is molar mass the same as molecular weight?
They are the same number in ordinary use but not the same quantity. Molecular weight, properly relative molecular mass, is a ratio and has no unit: for sodium nitrite it is 68.994769. Molar mass carries grams per mole: 68.994769 g/mol. Because the mole is defined so those agree, you can read one off the other.
Why is the molar mass not a whole number?
Because standard atomic weights are averages over the isotopes found in nature. Oxygen is quoted as 15.999 rather than a whole number for that reason, and the same applies to the other elements here, which is why sodium nitrite comes out at 68.994769 g/mol rather than 69.
Molar mass, composition and mole equivalents of sodium nitrite
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 2 | 15.999 | 31.998 | 46.38% |
| Sodium (Na) | 1 | 22.98977 | 22.98977 | 33.32% |
| Nitrogen (N) | 1 | 14.007 | 14.007 | 20.3% |
| Total — one mole of sodium nitrite | 68.994769 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 68.994769 g/mol.
| Amount | Mass (g) | Mass (mg) | Formula units |
|---|---|---|---|
| 1 µmol | 0.000069 | 0.0689948 | 6.022e+17 |
| 10 µmol | 0.000689948 | 0.689948 | 6.022e+18 |
| 100 µmol | 0.00689948 | 6.89948 | 6.022e+19 |
| 1 mmol | 0.0689948 | 68.9948 | 6.022e+20 |
| 10 mmol | 0.689948 | 689.948 | 6.022e+21 |
| 50 mmol | 3.44974 | 3449.74 | 3.011e+22 |
| 100 mmol | 6.89948 | 6899.48 | 6.022e+22 |
| 250 mmol | 17.2487 | 17,248.7 | 1.506e+23 |
| 500 mmol | 34.4974 | 34,497.4 | 3.011e+23 |
| 750 mmol | 51.7461 | 51,746.1 | 4.517e+23 |
| 1 mol | 68.9948 | 68,994.8 | 6.022e+23 |
| 2 mol | 137.99 | 137,990 | 1.204e+24 |
| 5 mol | 344.974 | 344,974 | 3.011e+24 |
| 10 mol | 689.948 | 689,948 | 6.022e+24 |
Mass is the amount multiplied by 68.994769 g/mol. The last column is that amount multiplied by the Avogadro constant, 6.02214076 × 10²³ per mole.
| Compound | Formula | Molar mass (g/mol) | Millimoles in 1 g |
|---|---|---|---|
| Ammonium chloride | NH4Cl | 53.489 | 18.695 |
| Sodium chloride | NaCl | 58.43977 | 17.112 |
| Sodium nitrite (this page) | NaNO2 | 68.99477 | 14.494 |
| Sodium hypochlorite | NaClO | 74.43877 | 13.434 |
| Potassium chloride | KCl | 74.5483 | 13.414 |
| Ammonium nitrate | NH4NO3 | 80.043 | 12.493 |
| Sodium bicarbonate | NaHCO3 | 84.00577 | 11.904 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.