Moles to grams for sulfuric acid is a multiplication by 98.072 g/mol. A mole weighs 98.072 g, 100 mmol weighs 9.8072 g, 10 mmol weighs 0.98072 g and a millimole is 98.072 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. Sulfuric acid is 2 × 1.008 (H) + 32.06 (S) + 4 × 15.999 (O), which is 98.072 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: 4 of the 7 atoms in a formula unit are oxygen, and they account for 63.996 g of the 98.072 g, or 65.25% 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.
Battery acid and the most produced industrial chemical. Concentrated is 98% w/w, about 18.4 mol/L, and it must be added to water rather than the reverse. At 98.072 g/mol it is heavier than 8 of the 12 acids covered here, and that ranking matters more than it looks: phosphoric acid has a molar mass of 97.99376 g/mol, so a gram of it contains 0.0798% more formula units than a gram of sulfuric 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 98.072 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 sulfuric acid you need, in moles
98.072- The molar mass of sulfuric 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 98.072 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 sulfuric acid in grams
5 mmol × 98.072 g/mol = 0.49036 g, which is 490.36 mg. Doubling the amount doubles the mass to 0.98072 g, because the relationship is a plain proportion once the molar mass is fixed.
250 mmol of sulfuric acid in grams
250 mmol × 98.072 g/mol = 24.518 g, which is 24,518 mg. Doubling the amount doubles the mass to 49.036 g, because the relationship is a plain proportion once the molar mass is fixed.
2 mol of sulfuric acid in grams
2 mol × 98.072 g/mol = 196.144 g, which is 196,144 mg. Doubling the amount doubles the mass to 392.288 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 sulfuric acid (H2SO4)?
It is 98.072 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 2 × 1.008 (H) + 32.06 (S) + 4 × 15.999 (O). One mole of sulfuric acid therefore weighs 98.072 g, and a gram of it is 10.197 mmol.
What percentage of sulfuric acid is oxygen?
65.25% by mass. Each formula unit contains 4 oxygen atoms contributing 63.996 g of the 98.072 g total, so 100 g of sulfuric acid contains 65.25 g of oxygen and a kilogram contains 652.54 g of it.
How many grams is one mole of sulfuric acid?
98.072 g, by definition of the molar mass. Two moles is 196.144 g and half a mole is 49.036 g.
How many grams is 0.1 mol, and how many milligrams is 1 mmol?
0.1 mol of sulfuric acid is 9.8072 g. One millimole is 98.072 mg and one micromole is 98.072 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 0.9807 mg of sulfuric acid, weigh 9.807 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, H2SO4, at 98.072 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 sulfuric acid
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 4 | 15.999 | 63.996 | 65.25% |
| Sulfur (S) | 1 | 32.06 | 32.06 | 32.69% |
| Hydrogen (H) | 2 | 1.008 | 2.016 | 2.056% |
| Total — one mole of sulfuric acid | 98.072 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 98.072 g/mol.
| Wanted | Weigh (g) | Weigh (mg) | With 2% over (g) |
|---|---|---|---|
| 1 µmol | 0.000098 | 0.098072 | 0.000100033 |
| 10 µmol | 0.00098072 | 0.98072 | 0.00100033 |
| 100 µmol | 0.0098072 | 9.8072 | 0.0100033 |
| 1 mmol | 0.098072 | 98.072 | 0.100033 |
| 10 mmol | 0.98072 | 980.72 | 1.00033 |
| 50 mmol | 4.9036 | 4903.6 | 5.00167 |
| 100 mmol | 9.8072 | 9807.2 | 10.0033 |
| 250 mmol | 24.518 | 24,518 | 25.0084 |
| 500 mmol | 49.036 | 49,036 | 50.0167 |
| 750 mmol | 73.554 | 73,554 | 75.0251 |
| 1 mol | 98.072 | 98,072 | 100.033 |
| 2 mol | 196.144 | 196,144 | 200.067 |
| 5 mol | 490.36 | 490,360 | 500.167 |
| 10 mol | 980.72 | 980,720 | 1000.33 |
Weigh is the amount multiplied by 98.072 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 (this page) | H2SO4 | 98.072 | 10.197 |
| Tartaric acid | 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.