Going from grams to moles for silver nitrate means dividing by its molar mass, 169.8722 g/mol. One gram is 0.00588678 mol, or 5.88678 mmol; 100 mg is 0.58868 mmol; and a 169.8722 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, AgNO3, which is where these figures come from.
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.
Balance resolution is the practical limit here. On a two-decimal balance the smallest step is 10 mg, which is 0.05887 mmol of silver nitrate; on a three-decimal balance it is 1 mg, or 5.887 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.
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
m- The mass you weighed, in grams
169.8722- The molar mass of silver nitrate 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 169.8722 g/mol, the molar mass of silver nitrate.
- 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 silver nitrate in moles
0.25 ÷ 169.8722 = 0.00147169 mol, or 1.4717 mmol. If the balance was reading to 1 mg, the last digit of that mass is worth 5.887 µmol, so quoting the answer to more than four significant figures claims a precision the weighing did not have.
2 g of silver nitrate in moles
2 ÷ 169.8722 = 0.0117736 mol, or 11.774 mmol. If the balance was reading to 1 mg, the last digit of that mass is worth 5.887 µmol, so quoting the answer to more than four significant figures claims a precision the weighing did not have.
25 g of silver nitrate in moles
25 ÷ 169.8722 = 0.147169 mol, or 147.17 mmol. If the balance was reading to 1 mg, the last digit of that mass is worth 5.887 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 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 do I convert grams of silver nitrate to moles?
Divide the mass in grams by 169.8722 g/mol. So 1 g is 0.00588678 mol, 10 g is 0.0588678 mol and 100 g is 0.588678 mol. Nothing else enters the calculation — no volume, no temperature, no concentration.
How many moles is 100 g of silver nitrate?
0.588678 mol, which is 588.678 mmol. Read the other way, one mole of silver nitrate is 169.8722 g, so 100 g is 0.5887 of a mole.
What about milligrams and micromoles?
The same division, scaled. A milligram of silver nitrate is 5.8868 µmol, 10 mg is 58.868 µmol and 100 mg is 0.58868 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 silver nitrate, which is 0.00576904 mol rather than 0.00588678 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 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.
| On the balance | Moles | Millimoles | Micromoles |
|---|---|---|---|
| 1 mg | 0.000006 | 0.00588678 | 5.88678 |
| 5 mg | 0.000029 | 0.0294339 | 29.4339 |
| 10 mg | 0.000059 | 0.0588678 | 58.8678 |
| 25 mg | 0.000147169 | 0.147169 | 147.169 |
| 50 mg | 0.000294339 | 0.294339 | 294.339 |
| 100 mg | 0.000588678 | 0.588678 | 588.678 |
| 250 mg | 0.00147169 | 1.47169 | 1471.69 |
| 500 mg | 0.00294339 | 2.94339 | 2943.39 |
| 1 g | 0.00588678 | 5.88678 | 5886.78 |
| 2 g | 0.0117736 | 11.7736 | 11,773.6 |
| 5 g | 0.0294339 | 29.4339 | 29,433.9 |
| 10 g | 0.0588678 | 58.8678 | 58,867.8 |
| 25 g | 0.147169 | 147.169 | 147,169 |
| 50 g | 0.294339 | 294.339 | 294,339 |
| 100 g | 0.588678 | 588.678 | 588,678 |
| 250 g | 1.47169 | 1471.69 | 1471694.603355 |
| 500 g | 2.94339 | 2943.39 | 2943389.206710 |
Every row is the mass divided by 169.8722 g/mol. A balance reading to 1 mg resolves 5.887 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 |
|---|---|---|---|
| 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.