Moles to grams for sodium bicarbonate is a multiplication by 84.005769 g/mol. A mole weighs 84.00577 g, 100 mmol weighs 8.40058 g, 10 mmol weighs 0.840058 g and a millimole is 84.0058 mg. Those four figures cover most of what gets weighed out in practice, and the table below extends them from a micromole up to ten moles.
The figure comes from the formula. Sodium bicarbonate is 22.9898 (Na) + 1.008 (H) + 12.011 (C) + 3 × 15.999 (O), which is 84.005769 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: 3 of the 6 atoms in a formula unit are oxygen, and they account for 47.997 g of the 84.00577 g, or 57.14% by mass. The derivation table below breaks the whole molecule down element by element.
Two habits make the weighed mass match the calculation. Weigh into a container you have tared rather than onto paper, because what stays behind on paper is a real loss — on a 100 mg weighing it is easily a percent. And when the target is under about 20 mg, weigh ten times that and dilute, since the absolute error of the balance does not shrink with the sample.
Baking soda. It decomposes above about 50 degrees C in solution, so a stock solution does not keep the way a chloride does. At 84.00577 g/mol it is heavier than 6 of the 34 salts covered here, and that ranking matters more than it looks: ammonium nitrate has a molar mass of 80.043 g/mol, so a gram of it contains 4.95% more formula units than a gram of sodium bicarbonate. Weigh by mass and you are not weighing equal amounts of substance.
Purity is the usual gap between the calculation and the balance. A reagent sold at 98% means 1.6801 g of a nominal 84.00577 g is something else, so for exact work you divide the weighed mass by the assay figure on the certificate. For most purposes the difference is smaller than the error in reading the meniscus, but it is systematic rather than random, so it does not average out.
The formula
n- The amount of sodium bicarbonate you need, in moles
84.005769- The molar mass of sodium bicarbonate in g/mol, derived from its formula
m- The mass to weigh out, in grams
How it works, step by step
- Enter the amount you need, in moles.
- It is multiplied by 84.005769 g/mol.
- The result is the mass to weigh out, also given in milligrams.
- Weigh into a tared container; anything left in the boat is a real loss from the amount you calculated.
Worked examples
5 mmol of sodium bicarbonate in grams
5 mmol × 84.00577 g/mol = 0.420029 g, which is 420.029 mg. Doubling the amount doubles the mass to 0.840058 g, because the relationship is a plain proportion once the molar mass is fixed.
250 mmol of sodium bicarbonate in grams
250 mmol × 84.00577 g/mol = 21.0014 g, which is 21,001.4 mg. Doubling the amount doubles the mass to 42.0029 g, because the relationship is a plain proportion once the molar mass is fixed.
2 mol of sodium bicarbonate in grams
2 mol × 84.00577 g/mol = 168.012 g, which is 168,012 mg. Doubling the amount doubles the mass to 336.023 g, because the relationship is a plain proportion once the molar mass is fixed.
How to read your score
Frequently asked questions
What is the molar mass of sodium bicarbonate (NaHCO3)?
It is 84.005769 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 22.9898 (Na) + 1.008 (H) + 12.011 (C) + 3 × 15.999 (O). One mole of sodium bicarbonate therefore weighs 84.00577 g, and a gram of it is 11.904 mmol.
What percentage of sodium bicarbonate is oxygen?
57.14% by mass. Each formula unit contains 3 oxygen atoms contributing 47.997 g of the 84.00577 g total, so 100 g of sodium bicarbonate contains 57.14 g of oxygen and a kilogram contains 571.35 g of it.
How many grams is one mole of sodium bicarbonate?
84.005769 g, by definition of the molar mass. Two moles is 168.0115 g and half a mole is 42.00288 g.
How many grams is 0.1 mol, and how many milligrams is 1 mmol?
0.1 mol of sodium bicarbonate is 8.40058 g. One millimole is 84.0058 mg and one micromole is 84.0058 µg, which is the range most bench work sits in.
How do I weigh out an amount too small for my balance?
Weigh a larger mass and dilute it. To get 0.8401 mg of sodium bicarbonate, weigh 8.401 mg into 100 mL, then take 10 mL of that: the absolute error of the balance stays the same while the amount delivered falls by a factor of ten.
Should I use the hydrate or the anhydrous molar mass?
This page is the anhydrous form, NaHCO3, at 84.005769 g/mol. If your jar is the other form the molar mass differs and so will every mass you weigh, so check the label before using the figure. Salts that are sold as hydrates weigh more per mole because the water is part of the crystal.
Moles to grams reference for sodium bicarbonate
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 3 | 15.999 | 47.997 | 57.14% |
| Sodium (Na) | 1 | 22.98977 | 22.98977 | 27.37% |
| Carbon (C) | 1 | 12.011 | 12.011 | 14.3% |
| Hydrogen (H) | 1 | 1.008 | 1.008 | 1.2% |
| Total — one mole of sodium bicarbonate | 84.005769 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 84.005769 g/mol.
| Wanted | Weigh (g) | Weigh (mg) | With 2% over (g) |
|---|---|---|---|
| 1 µmol | 0.000084 | 0.0840058 | 0.000086 |
| 10 µmol | 0.000840058 | 0.840058 | 0.000856859 |
| 100 µmol | 0.00840058 | 8.40058 | 0.00856859 |
| 1 mmol | 0.0840058 | 84.0058 | 0.0856859 |
| 10 mmol | 0.840058 | 840.058 | 0.856859 |
| 50 mmol | 4.20029 | 4200.29 | 4.28429 |
| 100 mmol | 8.40058 | 8400.58 | 8.56859 |
| 250 mmol | 21.0014 | 21,001.4 | 21.4215 |
| 500 mmol | 42.0029 | 42,002.9 | 42.8429 |
| 750 mmol | 63.0043 | 63,004.3 | 64.2644 |
| 1 mol | 84.0058 | 84,005.8 | 85.6859 |
| 2 mol | 168.012 | 168,012 | 171.372 |
| 5 mol | 420.029 | 420,029 | 428.429 |
| 10 mol | 840.058 | 840,058 | 856.859 |
Weigh is the amount multiplied by 84.005769 g/mol. The last column carries a 2% allowance, which is what you take when some of the solid will be left in the weighing boat.
| Compound | Formula | Molar mass (g/mol) | Millimoles in 1 g |
|---|---|---|---|
| Sodium hypochlorite | NaClO | 74.43877 | 13.434 |
| Potassium chloride | KCl | 74.5483 | 13.414 |
| Ammonium nitrate | NH4NO3 | 80.043 | 12.493 |
| Sodium bicarbonate (this page) | NaHCO3 | 84.00577 | 11.904 |
| Sodium nitrate | NaNO3 | 84.99377 | 11.766 |
| Magnesium chloride | MgCl2 | 95.205 | 10.504 |
| Calcium carbonate | CaCO3 | 100.086 | 9.9914 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.