The molar mass of ammonia (NH3) is 17.031 g/mol.
Case matters: CO is carbon monoxide, Co is
cobalt. Brackets and hydrates are fine — try
or
.
| Element | Atoms | Atomic mass | Mass contributed | Percent |
|---|---|---|---|---|
| Hydrogen (H) | 3 | 1.0080 | 3.024 | 17.76% |
| Nitrogen (N) | 1 | 14.007 | 14.007 | 82.24% |
| Total | 4 | 17.031 | 100.00% |
3.024 + 14.007 = 17.031 g/mol
Grams and moles
25 g of ammonia is 1.468 mol, because 25 ÷ 17.031 = 1.468.
These elements have no single atomic weight. Their isotopic mix varies slightly depending on where on Earth the sample came from, so the figure used here is the conventional value IUPAC publishes for when one number is needed: hydrogen is 1.0080, and really lies between 1.00784 and 1.00811; nitrogen is 14.007, and really lies between 14.00643 and 14.00728.
Ammonia weighs 17.031 g/mol, of which nitrogen holds 82.24%. Three hydrogens contribute just 3.024 g/mol between them.
That mass fraction is the number the fertiliser industry runs on. Ammonia is how atmospheric nitrogen becomes available to crops, and the Haber process that makes it consumes somewhere between one and two percent of world energy output. Every kilogram carries 823 grams of nitrogen, and fertiliser grades are quoted as percentage nitrogen for exactly that reason.
Set it against the ammonium ion, NH4 carrying a single positive charge, which is what appears in ammonium nitrate and ammonium sulfate. One extra hydrogen takes the mass to 18.039 and changes the chemistry completely: ammonia is a gas and a weak base, ammonium is a cation that sits in crystal lattices. Students write one when they mean the other constantly, and that single hydrogen is the only visible difference.