Moles to grams for silicon dioxide is a multiplication by 60.083 g/mol. A mole weighs 60.083 g, 100 mmol weighs 6.0083 g, 10 mmol weighs 0.60083 g and a millimole is 60.083 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. Silicon dioxide is 28.085 (Si) + 2 × 15.999 (O), which is 60.083 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 3 atoms in a formula unit are oxygen, and they account for 31.998 g of the 60.083 g, or 53.26% 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.
Sand, quartz and glass. Also the anti-caking agent in powdered food, where it appears as silica. At 60.083 g/mol it is heavier than 1 of the 8 oxides covered here, and that ranking matters more than it looks: calcium oxide has a molar mass of 56.077 g/mol, so a gram of it contains 7.14% more formula units than a gram of silicon dioxide. 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, 1.2017 g of every 60.083 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
n- The amount of silicon dioxide you need, in moles
60.083- The molar mass of silicon dioxide 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 60.083 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 silicon dioxide in grams
5 mmol × 60.083 g/mol = 0.300415 g, which is 300.415 mg. Doubling the amount doubles the mass to 0.60083 g, because the relationship is a plain proportion once the molar mass is fixed.
250 mmol of silicon dioxide in grams
250 mmol × 60.083 g/mol = 15.0207 g, which is 15,020.8 mg. Doubling the amount doubles the mass to 30.0415 g, because the relationship is a plain proportion once the molar mass is fixed.
2 mol of silicon dioxide in grams
2 mol × 60.083 g/mol = 120.166 g, which is 120,166 mg. Doubling the amount doubles the mass to 240.332 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 silicon dioxide (SiO2)?
It is 60.083 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 28.085 (Si) + 2 × 15.999 (O). One mole of silicon dioxide therefore weighs 60.083 g, and a gram of it is 16.644 mmol.
What percentage of silicon dioxide is oxygen?
53.26% by mass. Each formula unit contains 2 oxygen atoms contributing 31.998 g of the 60.083 g total, so 100 g of silicon dioxide contains 53.26 g of oxygen and a kilogram contains 532.56 g of it.
How many grams is one mole of silicon dioxide?
60.083 g, by definition of the molar mass. Two moles is 120.166 g and half a mole is 30.0415 g.
How many grams is 0.1 mol, and how many milligrams is 1 mmol?
0.1 mol of silicon dioxide is 6.0083 g. One millimole is 60.083 mg and one micromole is 60.083 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 0.6008 mg of silicon dioxide, weigh 6.008 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, SiO2, at 60.083 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 silicon dioxide
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 2 | 15.999 | 31.998 | 53.26% |
| Silicon (Si) | 1 | 28.085 | 28.085 | 46.74% |
| Total — one mole of silicon dioxide | 60.083 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 60.083 g/mol.
| Wanted | Weigh (g) | Weigh (mg) | With 2% over (g) |
|---|---|---|---|
| 1 µmol | 0.000060 | 0.060083 | 0.000061 |
| 10 µmol | 0.00060083 | 0.60083 | 0.000612847 |
| 100 µmol | 0.0060083 | 6.0083 | 0.00612847 |
| 1 mmol | 0.060083 | 60.083 | 0.0612847 |
| 10 mmol | 0.60083 | 600.83 | 0.612847 |
| 50 mmol | 3.00415 | 3004.15 | 3.06423 |
| 100 mmol | 6.0083 | 6008.3 | 6.12847 |
| 250 mmol | 15.0207 | 15,020.8 | 15.3212 |
| 500 mmol | 30.0415 | 30,041.5 | 30.6423 |
| 750 mmol | 45.0622 | 45,062.2 | 45.9635 |
| 1 mol | 60.083 | 60,083 | 61.2847 |
| 2 mol | 120.166 | 120,166 | 122.569 |
| 5 mol | 300.415 | 300,415 | 306.423 |
| 10 mol | 600.83 | 600,830 | 612.847 |
Weigh is the amount multiplied by 60.083 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 |
|---|---|---|---|
| Calcium oxide | CaO | 56.077 | 17.833 |
| Silicon dioxide (this page) | SiO2 | 60.083 | 16.644 |
| Copper(II) oxide | CuO | 79.545 | 12.572 |
| Titanium dioxide | TiO2 | 79.865 | 12.521 |
| Zinc oxide | ZnO | 81.379 | 12.288 |
| Manganese dioxide | MnO2 | 86.93604 | 11.503 |
| Aluminium oxide | Al2O3 | 101.9601 | 9.8078 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.