Moles to grams for tartaric acid is a multiplication by 150.086 g/mol. A mole weighs 150.086 g, 100 mmol weighs 15.0086 g, 10 mmol weighs 1.50086 g and a millimole is 150.086 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. Tartaric acid is 4 × 12.011 (C) + 6 × 1.008 (H) + 6 × 15.999 (O), which is 150.086 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: 6 of the 16 atoms in a formula unit are oxygen, and they account for 95.994 g of the 150.086 g, or 63.96% 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.
The acid of grapes and the acid half of baking powder as cream of tartar. Used to adjust the acidity of wine before fermentation. At 150.086 g/mol it is heavier than 9 of the 12 acids covered here, and that ranking matters more than it looks: sulfuric acid has a molar mass of 98.072 g/mol, so a gram of it contains 53% more formula units than a gram of tartaric acid. Weigh by mass and you are not weighing equal amounts of substance.
One more step applies if you are starting from a concentrated bottle. Concentrated acids are labelled as a percentage by weight together with a density, not as a molarity, so getting to mol/L means multiplying density by that percentage and dividing by 150.086 g/mol. A page like this one gives you the last of those three numbers; the first two are on the bottle, and they vary between grades.
The formula
n- The amount of tartaric acid you need, in moles
150.086- The molar mass of tartaric acid 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 150.086 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 tartaric acid in grams
5 mmol × 150.086 g/mol = 0.75043 g, which is 750.43 mg. Doubling the amount doubles the mass to 1.50086 g, because the relationship is a plain proportion once the molar mass is fixed.
250 mmol of tartaric acid in grams
250 mmol × 150.086 g/mol = 37.5215 g, which is 37,521.5 mg. Doubling the amount doubles the mass to 75.043 g, because the relationship is a plain proportion once the molar mass is fixed.
2 mol of tartaric acid in grams
2 mol × 150.086 g/mol = 300.172 g, which is 300,172 mg. Doubling the amount doubles the mass to 600.344 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 tartaric acid (C4H6O6)?
It is 150.086 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 4 × 12.011 (C) + 6 × 1.008 (H) + 6 × 15.999 (O). One mole of tartaric acid therefore weighs 150.086 g, and a gram of it is 6.6628 mmol.
What percentage of tartaric acid is oxygen?
63.96% by mass. Each formula unit contains 6 oxygen atoms contributing 95.994 g of the 150.086 g total, so 100 g of tartaric acid contains 63.96 g of oxygen and a kilogram contains 639.59 g of it.
How many grams is one mole of tartaric acid?
150.086 g, by definition of the molar mass. Two moles is 300.172 g and half a mole is 75.043 g.
How many grams is 0.1 mol, and how many milligrams is 1 mmol?
0.1 mol of tartaric acid is 15.0086 g. One millimole is 150.086 mg and one micromole is 150.086 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 1.501 mg of tartaric acid, weigh 15.01 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, C4H6O6, at 150.086 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 tartaric acid
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 6 | 15.999 | 95.994 | 63.96% |
| Carbon (C) | 4 | 12.011 | 48.044 | 32.01% |
| Hydrogen (H) | 6 | 1.008 | 6.048 | 4.03% |
| Total — one mole of tartaric acid | 150.086 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 150.086 g/mol.
| Wanted | Weigh (g) | Weigh (mg) | With 2% over (g) |
|---|---|---|---|
| 1 µmol | 0.000150086 | 0.150086 | 0.000153088 |
| 10 µmol | 0.00150086 | 1.50086 | 0.00153088 |
| 100 µmol | 0.0150086 | 15.0086 | 0.0153088 |
| 1 mmol | 0.150086 | 150.086 | 0.153088 |
| 10 mmol | 1.50086 | 1500.86 | 1.53088 |
| 50 mmol | 7.5043 | 7504.3 | 7.65439 |
| 100 mmol | 15.0086 | 15,008.6 | 15.3088 |
| 250 mmol | 37.5215 | 37,521.5 | 38.2719 |
| 500 mmol | 75.043 | 75,043 | 76.5439 |
| 750 mmol | 112.565 | 112,565 | 114.816 |
| 1 mol | 150.086 | 150,086 | 153.088 |
| 2 mol | 300.172 | 300,172 | 306.175 |
| 5 mol | 750.43 | 750,430 | 765.439 |
| 10 mol | 1500.86 | 1500860.000000 | 1530.88 |
Weigh is the amount multiplied by 150.086 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 |
|---|---|---|---|
| Oxalic acid | C2H2O4 | 90.034 | 11.107 |
| Lactic acid | C3H6O3 | 90.078 | 11.101 |
| Phosphoric acid | H3PO4 | 97.99376 | 10.205 |
| Sulfuric acid | H2SO4 | 98.072 | 10.197 |
| Tartaric acid (this page) | C4H6O6 | 150.086 | 6.6628 |
| Ascorbic acid | C6H8O6 | 176.124 | 5.6778 |
| Citric acid | C6H8O7 | 192.123 | 5.205 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.