Going from grams to moles for sodium bicarbonate means dividing by its molar mass, 84.005769 g/mol. One gram is 0.0119039 mol, or 11.9039 mmol; 100 mg is 1.1904 mmol; and a 84.00577 g portion is exactly one mole. The division is the whole calculation, but the molar mass has to be the one for the exact formula you have, NaHCO3, which is where these figures come from.
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.
Balance resolution is the practical limit here. On a two-decimal balance the smallest step is 10 mg, which is 0.119 mmol of sodium bicarbonate; on a three-decimal balance it is 1 mg, or 11.9 µmol. To hit a target within 1% you therefore need to weigh at least a gram on the first and at least 100 mg on the second, and below that a stock solution measured by pipette beats weighing.
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
m- The mass you weighed, in grams
84.005769- The molar mass of sodium bicarbonate in g/mol, derived from its formula
n- The amount of substance in moles
How it works, step by step
- Enter the mass you weighed, in grams.
- It is divided by 84.005769 g/mol, the molar mass of sodium bicarbonate.
- The result is the amount of substance in moles, with millimoles and micromoles beneath it.
- Check it against the table if you want the figure for a standard weighing rather than a typed mass.
Worked examples
0.25 g of sodium bicarbonate in moles
0.25 ÷ 84.00577 = 0.00297599 mol, or 2.976 mmol. If the balance was reading to 1 mg, the last digit of that mass is worth 11.9 µmol, so quoting the answer to more than four significant figures claims a precision the weighing did not have.
2 g of sodium bicarbonate in moles
2 ÷ 84.00577 = 0.0238079 mol, or 23.808 mmol. If the balance was reading to 1 mg, the last digit of that mass is worth 11.9 µmol, so quoting the answer to more than four significant figures claims a precision the weighing did not have.
25 g of sodium bicarbonate in moles
25 ÷ 84.00577 = 0.297599 mol, or 297.6 mmol. If the balance was reading to 1 mg, the last digit of that mass is worth 11.9 µmol, so quoting the answer to more than four significant figures claims a precision the weighing did not have.
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 do I convert grams of sodium bicarbonate to moles?
Divide the mass in grams by 84.005769 g/mol. So 1 g is 0.0119039 mol, 10 g is 0.119039 mol and 100 g is 1.19039 mol. Nothing else enters the calculation — no volume, no temperature, no concentration.
How many moles is 100 g of sodium bicarbonate?
1.19039 mol, which is 1190.39 mmol. Read the other way, one mole of sodium bicarbonate is 84.00577 g, so 100 g is 1.19 of a mole.
What about milligrams and micromoles?
The same division, scaled. A milligram of sodium bicarbonate is 11.904 µmol, 10 mg is 119.04 µmol and 100 mg is 1.1904 mmol. Working in µmol per mg avoids the string of leading zeros that mol per g produces at this scale.
Does purity change the number of moles?
Yes, in proportion. A 98% pure sample weighing 1 g contains 0.98 g of sodium bicarbonate, which is 0.0116659 mol rather than 0.0119039 mol. The calculator assumes the mass you enter is the compound itself, so divide by the assay figure first if you need the corrected amount.
Grams to moles 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.
| On the balance | Moles | Millimoles | Micromoles |
|---|---|---|---|
| 1 mg | 0.000012 | 0.0119039 | 11.9039 |
| 5 mg | 0.000060 | 0.0595197 | 59.5197 |
| 10 mg | 0.000119039 | 0.119039 | 119.039 |
| 25 mg | 0.000297599 | 0.297599 | 297.599 |
| 50 mg | 0.000595197 | 0.595197 | 595.197 |
| 100 mg | 0.00119039 | 1.19039 | 1190.39 |
| 250 mg | 0.00297599 | 2.97599 | 2975.99 |
| 500 mg | 0.00595197 | 5.95197 | 5951.97 |
| 1 g | 0.0119039 | 11.9039 | 11,903.9 |
| 2 g | 0.0238079 | 23.8079 | 23,807.9 |
| 5 g | 0.0595197 | 59.5197 | 59,519.7 |
| 10 g | 0.119039 | 119.039 | 119,039 |
| 25 g | 0.297599 | 297.599 | 297,599 |
| 50 g | 0.595197 | 595.197 | 595,197 |
| 100 g | 1.19039 | 1190.39 | 1190394.431919 |
| 250 g | 2.97599 | 2975.99 | 2975986.079798 |
| 500 g | 5.95197 | 5951.97 | 5951972.159596 |
Every row is the mass divided by 84.005769 g/mol. A balance reading to 1 mg resolves 11.9 µmol of this compound, which is the smallest step the middle columns can really move in.
| 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.