Chapter: Some Basic Concepts of Chemistry· Chemistry
12 g of carbon is one mole of carbon atoms, while 12 u is the mass of a single carbon-12 atom.
(Reading the question as "12 g of carbon" and "12 u of carbon".)
| 12 g of carbon | 12 u of carbon |
|---|---|
| Gram atomic mass (molar mass) of carbon. | Atomic mass of one carbon-12 atom. |
| Contains 1 mol, i.e. \(6.022\times10^{23}\) atoms of C-12. | Refers to just one atom. |
| A macroscopic quantity that can be weighed on a balance. | A very tiny mass: \(12\times1.66\times10^{-24}\ \mathrm{g} \approx 1.99\times10^{-23}\ \mathrm{g}\). |
| Unit: gram (g). | Unit: unified atomic mass unit (u). |
Link between them: \(1\ \mathrm{u} = \dfrac{1}{12}\) of the mass of one C-12 atom, so 12 u × Avogadro's number = 12 g.