Molar Mass of NH3
Ammonia — 17.031 g/mol.
The molar mass of NH3 (ammonia) is 17.031 g/mol. The feedstock for nitrogen fertiliser and a common laboratory base.
M(NH3) = (1 × 14.01) + (3 × 1.008) = 17.031 g/mol
Working
| Element | Atoms | Atomic mass | Subtotal | % by mass |
|---|---|---|---|---|
| N | 1 | 14.01 | 14.0070 | 82.24% |
| H | 3 | 1.008 | 3.0240 | 17.76% |
| Total | 17.0310 | 100% |
How this is calculated
Count the atoms of each element in the formula, multiply each count by that element's standard atomic weight, and add the results. The answer is in grams per mole: the mass of 6.022 × 1023 formula units.
Percent composition
Each element's share is its subtotal divided by the total, times 100. This is what empirical-formula questions run in reverse — given the percentages, recover the ratio of atoms.
Work out any other formula with the molar mass calculator, which handles brackets and hydrates. Atomic weights are IUPAC standard values, the same table the calculator uses.