Molar MassMolar mass of silver nitrate (AgNO3)
The molar mass of silver nitrate, AgNO3, is 169.87 g/mol. One mole of it, which is 6.022 × 1023 formula units, has a mass of 169.87 grams.
169.87 g/mol
107.87 + 14.007 + 3 × 15.999 = 169.874 · 5 atoms in the formula · also called lunar caustic
About silver nitrate
Silver nitrate is a colourless salt that dissolves easily in water. Its solution gives a white precipitate with chlorides, the standard test for chloride ions. It darkens in light and stains skin black.
Other names: lunar caustic.
The working
The formula AgNO3 has 1 silver atom, 1 nitrogen atom and 3 oxygen atoms, 5 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Silver (Ag) | 1 | 107.87 | 107.870 | 63.50% |
| Nitrogen (N) | 1 | 14.007 | 14.007 | 8.25% |
| Oxygen (O) | 3 | 15.999 | 47.997 | 28.25% |
107.87 + 14.007 + 3 × 15.999 = 169.874 g/mol
With the rounded atomic masses used in many school books (Ag = 108, N = 14, O = 16) the answer is 170 g/mol. The difference from 169.87 is too small to matter in most school sums.
Percentage composition
By mass, AgNO3 is 63.50% silver, 8.25% nitrogen and 28.25% oxygen. The largest share comes from silver. In a 100 g sample there are 63.5 g of silver, 8.2 g of nitrogen and 28.3 g of oxygen.
Worked examples
Grams to moles. How many moles are in 25 g of AgNO3? Divide the mass by the molar mass: 25 ÷ 169.87 = 0.1472 mol.
Moles to grams. What is the mass of 0.1 mol of AgNO3? Multiply: 0.1 × 169.87 = 16.99 g.
Counting particles. 25 g contains 0.1472 mol × 6.022 × 1023 = 8.863 × 1022 formula units.
Making a solution. A 0.1 mol/L solution contains 0.1 × 169.87 = 16.99 g of AgNO3 in each litre. For 250 mL, weigh 4.247 g and make it up to the mark with water.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 16.99 g |
| 0.5 mol | 84.94 g |
| 1 mol | 169.9 g |
| 2 mol | 339.7 g |
| 5 mol | 849.4 g |
| Mass | Moles |
|---|---|
| 1 g | 0.005887 mol |
| 10 g | 0.05887 mol |
| 100 g | 0.5887 mol |
| 1 kg | 5.887 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of AgNO3?
The molar mass of silver nitrate (AgNO3) is 169.87 g/mol, or 169.874 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of AgNO3?
100 ÷ 169.87 = 0.5887 mol.
What is the mass of one formula unit of AgNO3?
Divide the molar mass by the Avogadro constant: 169.87 ÷ 6.022 × 1023 = 2.821 × 10-22 g.
What is the percentage of silver in AgNO3?
Silver makes up 63.50% of the mass of AgNO3: 1 × 107.87 ÷ 169.874 × 100.
Which values? This site uses the abridged standard atomic weights published by IUPAC (CIAAW), read on 12 November 2026. Your textbook or question paper may round them differently, for example H = 1 and O = 16, so its answer can differ slightly. In an exam, use the values the paper gives.