Molar MassMolar mass of nitrogen monoxide (NO)
The molar mass of nitrogen monoxide, NO, is 30.01 g/mol. One mole of it, which is 6.022 × 1023 molecules, has a mass of 30.01 grams.
30.01 g/mol
14.007 + 15.999 = 30.006 · 2 atoms in the formula · also called nitric oxide
About nitrogen monoxide
Nitrogen monoxide is a colourless gas that turns brown in air as it changes to nitrogen dioxide. Note that No, with a small o, is the element nobelium.
Other names: nitric oxide.
The working
The formula NO has 1 nitrogen atom and 1 oxygen atom, 2 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Nitrogen (N) | 1 | 14.007 | 14.007 | 46.68% |
| Oxygen (O) | 1 | 15.999 | 15.999 | 53.32% |
14.007 + 15.999 = 30.006 g/mol
With the rounded atomic masses used in many school books (N = 14, O = 16) the answer is 30 g/mol. The difference from 30.01 is too small to matter in most school sums.
Percentage composition
By mass, NO is 46.68% nitrogen and 53.32% oxygen. The largest share comes from oxygen. In a 100 g sample there are 46.7 g of nitrogen and 53.3 g of oxygen.
Worked examples
Grams to moles. How many moles are in 5 g of NO? Divide the mass by the molar mass: 5 ÷ 30.01 = 0.1666 mol.
Moles to grams. What is the mass of 0.25 mol of NO? Multiply: 0.25 × 30.01 = 7.502 g.
Counting particles. 5 g contains 0.1666 mol × 6.022 × 1023 = 1.003 × 1023 molecules, and 2.007 × 1023 atoms in all.
As a gas. At 0 °C and 1 atmosphere one mole of an ideal gas occupies 22.4 litres, so the density of NO is about 30.01 ÷ 22.4 = 1.34 g per litre. Air averages about 29 g/mol, so this gas is heavier than air.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 3.001 g |
| 0.5 mol | 15 g |
| 1 mol | 30.01 g |
| 2 mol | 60.01 g |
| 5 mol | 150 g |
| Mass | Moles |
|---|---|
| 1 g | 0.03333 mol |
| 10 g | 0.3333 mol |
| 100 g | 3.333 mol |
| 1 kg | 33.33 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of NO?
The molar mass of nitrogen monoxide (NO) is 30.01 g/mol, or 30.006 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of NO?
100 ÷ 30.01 = 3.333 mol.
What is the mass of one molecule of NO?
Divide the molar mass by the Avogadro constant: 30.01 ÷ 6.022 × 1023 = 4.983 × 10-23 g.
What is the percentage of oxygen in NO?
Oxygen makes up 53.32% of the mass of NO: 1 × 15.999 ÷ 30.006 × 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.