# How does atomic mass relate to the unit "mole"?

Oct 23, 2015

Avogadro's number (i.e. 1 mole) of atomic species (whatever these are) represents the atomic mass of this species.

#### Explanation:

The mole represents the link between atoms and molecules (of which we can conceive) to the macro world of grams and kilograms and analytical balances. The mass of a pure substance represents a specific number of pure substance 'molecules', as defined by molecular weight.

Oct 23, 2015

The relative atomic mass (atomic weight) in grams/mole (g/mol) is the molar mass of a substance, which means it is the mass of one mole of that substance.

#### Explanation:

For elements, the molar mass is the relative atomic mass (atomic weight) found on the periodic table, in g/mol.

For example, the molar masses of the following elements are:
$\text{H} :$$\text{1.00794 g/mol}$
$\text{C} :$$\text{12.0107 g/mol}$
$\text{O} :$$\text{15.999 g/mol}$

Therefore, one mole of hydrogen has a mass of $\text{1.00794 g}$; one mole of carbon has a mass of $\text{12.0107 g}$, and one mole of oxygen has a mass of $\text{15.999 g}$.

To determine the molar mass of compounds, the subscript of each element is multiplied times the molar mass of each element and the results are added.

For example, determine the molar mass of glucose, $\text{C"_6"H"_12"O"_6}$.

$\left(6 \times 12.0107 \text{g/mol")+(12xx1.00794"g/mol")+(6xx15.999"g/mol}\right) =$

(72.0642"g/mol")+(12.0953"g/mol")+(95.994"g/mol")="180.159 g/mol"

Therefore, one mole of glucose has a mass of $\text{180.159 g}$.