Molar MassMolar mass of urea (CO(NH2)2)
The molar mass of urea, CO(NH2)2, is 60.06 g/mol. One mole of it, which is 6.022 × 1023 molecules, has a mass of 60.06 grams.
60.06 g/mol
12.011 + 15.999 + 2 × 14.007 + 4 × 1.0080 = 60.056 · 8 atoms in the formula · also called carbamide
About urea
Urea is the most widely used nitrogen fertiliser and the main nitrogen waste in urine. Nearly half of its mass is nitrogen. The bracket holds two NH2 groups.
Other names: carbamide.
The working
The formula CO(NH2)2 has 1 carbon atom, 1 oxygen atom, 2 nitrogen atoms and 4 hydrogen atoms, 8 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Carbon (C) | 1 | 12.011 | 12.011 | 20.00% |
| Oxygen (O) | 1 | 15.999 | 15.999 | 26.64% |
| Nitrogen (N) | 2 | 14.007 | 28.014 | 46.65% |
| Hydrogen (H) | 4 | 1.0080 | 4.032 | 6.71% |
12.011 + 15.999 + 2 × 14.007 + 4 × 1.0080 = 60.056 g/mol
With the rounded atomic masses used in many school books (C = 12, O = 16, N = 14, H = 1) the answer is 60 g/mol. The difference from 60.06 is too small to matter in most school sums.
Percentage composition
By mass, CO(NH2)2 is 20.00% carbon, 26.64% oxygen, 46.65% nitrogen and 6.71% hydrogen. The largest share comes from nitrogen. In a 100 g sample there are 20.0 g of carbon, 26.6 g of oxygen, 46.6 g of nitrogen and 6.7 g of hydrogen.
Notice that hydrogen has more atoms in the formula (4) than nitrogen (2), yet gives a smaller share of the mass. Percentage by mass depends on how heavy each atom is, not only on how many there are.
Worked examples
Grams to moles. How many moles are in 20 g of CO(NH2)2? Divide the mass by the molar mass: 20 ÷ 60.06 = 0.333 mol.
Moles to grams. What is the mass of 0.5 mol of CO(NH2)2? Multiply: 0.5 × 60.06 = 30.03 g.
Counting particles. 20 g contains 0.333 mol × 6.022 × 1023 = 2.006 × 1023 molecules, and 1.604 × 1024 atoms in all.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 6.006 g |
| 0.5 mol | 30.03 g |
| 1 mol | 60.06 g |
| 2 mol | 120.1 g |
| 5 mol | 300.3 g |
| Mass | Moles |
|---|---|
| 1 g | 0.01665 mol |
| 10 g | 0.1665 mol |
| 100 g | 1.665 mol |
| 1 kg | 16.65 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of CO(NH2)2?
The molar mass of urea (CO(NH2)2) is 60.06 g/mol, or 60.056 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of CO(NH2)2?
100 ÷ 60.06 = 1.665 mol.
What is the mass of one molecule of CO(NH2)2?
Divide the molar mass by the Avogadro constant: 60.06 ÷ 6.022 × 1023 = 9.973 × 10-23 g.
What is the percentage of nitrogen in CO(NH2)2?
Nitrogen makes up 46.65% of the mass of CO(NH2)2: 2 × 14.007 ÷ 60.056 × 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.