Moles to grams for silver nitrate is a multiplication by 169.8722 g/mol. A mole weighs 169.8722 g, 100 mmol weighs 16.9872 g, 10 mmol weighs 1.69872 g and a millimole is 169.872 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. Silver nitrate is 107.868 (Ag) + 14.007 (N) + 3 × 15.999 (O), which is 169.8722 g/mol, taking standard atomic weights, and every page here computes that sum rather than quoting it. Silver makes up the largest share of the mass: 1 of the 5 atoms in a formula unit is silver, and they account for 107.868 g of the 169.8722 g, or 63.5% 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 reagent for chloride tests and the silver source in mirroring and photography. Solutions darken in light and stain skin permanently. At 169.8722 g/mol it is heavier than 23 of the 34 salts covered here, and that ranking matters more than it looks: potassium iodide has a molar mass of 166.0028 g/mol, so a gram of it contains 2.33% more formula units than a gram of silver nitrate. 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, 3.3974 g of every 169.8722 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 silver nitrate you need, in moles
169.8722- The molar mass of silver nitrate 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 169.8722 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 silver nitrate in grams
5 mmol × 169.8722 g/mol = 0.849361 g, which is 849.361 mg. Doubling the amount doubles the mass to 1.69872 g, because the relationship is a plain proportion once the molar mass is fixed.
250 mmol of silver nitrate in grams
250 mmol × 169.8722 g/mol = 42.4681 g, which is 42,468.1 mg. Doubling the amount doubles the mass to 84.9361 g, because the relationship is a plain proportion once the molar mass is fixed.
2 mol of silver nitrate in grams
2 mol × 169.8722 g/mol = 339.744 g, which is 339,744 mg. Doubling the amount doubles the mass to 679.489 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 silver nitrate (AgNO3)?
It is 169.8722 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 107.868 (Ag) + 14.007 (N) + 3 × 15.999 (O). One mole of silver nitrate therefore weighs 169.8722 g, and a gram of it is 5.8868 mmol.
What percentage of silver nitrate is silver?
63.5% by mass. Each formula unit contains 1 silver atom contributing 107.868 g of the 169.8722 g total, so 100 g of silver nitrate contains 63.5 g of silver and a kilogram contains 635 g of it.
How many grams is one mole of silver nitrate?
169.8722 g, by definition of the molar mass. Two moles is 339.7444 g and half a mole is 84.9361 g.
How many grams is 0.1 mol, and how many milligrams is 1 mmol?
0.1 mol of silver nitrate is 16.9872 g. One millimole is 169.872 mg and one micromole is 169.872 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 1.699 mg of silver nitrate, weigh 16.99 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, AgNO3, at 169.8722 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 silver nitrate
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Silver (Ag) | 1 | 107.8682 | 107.8682 | 63.5% |
| Oxygen (O) | 3 | 15.999 | 47.997 | 28.25% |
| Nitrogen (N) | 1 | 14.007 | 14.007 | 8.246% |
| Total — one mole of silver nitrate | 169.8722 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 169.8722 g/mol.
| Wanted | Weigh (g) | Weigh (mg) | With 2% over (g) |
|---|---|---|---|
| 1 µmol | 0.000169872 | 0.169872 | 0.00017327 |
| 10 µmol | 0.00169872 | 1.69872 | 0.0017327 |
| 100 µmol | 0.0169872 | 16.9872 | 0.017327 |
| 1 mmol | 0.169872 | 169.872 | 0.17327 |
| 10 mmol | 1.69872 | 1698.72 | 1.7327 |
| 50 mmol | 8.49361 | 8493.61 | 8.66348 |
| 100 mmol | 16.9872 | 16,987.2 | 17.327 |
| 250 mmol | 42.4681 | 42,468.1 | 43.3174 |
| 500 mmol | 84.9361 | 84,936.1 | 86.6348 |
| 750 mmol | 127.404 | 127,404 | 129.952 |
| 1 mol | 169.872 | 169,872 | 173.27 |
| 2 mol | 339.744 | 339,744 | 346.539 |
| 5 mol | 849.361 | 849,361 | 866.348 |
| 10 mol | 1698.72 | 1698722.000000 | 1732.7 |
Weigh is the amount multiplied by 169.8722 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 |
|---|---|---|---|
| Iron(III) chloride | FeCl3 | 162.195 | 6.1654 |
| Trisodium phosphate | Na3PO4 | 163.9391 | 6.0998 |
| Potassium iodide | KI | 166.0028 | 6.024 |
| Silver nitrate (this page) | AgNO3 | 169.8722 | 5.8868 |
| Gypsum | CaSO4·2H2O | 172.164 | 5.8084 |
| Potassium sulfate | K2SO4 | 174.2526 | 5.7388 |
| Epsom salt | MgSO4·7H2O | 246.466 | 4.0574 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.