The mole
Tutorial 6
Molar mass
Reminder
One mole of atoms are $ 6.023 \cdot 10^{23} $ atoms
One mole of molecules are $ 6.023 \cdot 10^{23} $ molecules
The atomic (molar) mass of an element:
The atomic (molar) mass of an element ($ M $) is the mass (in grams) of one mole of atoms of this element!
The atomic (molar) masses are found in the → periodic table
Molar mass of a substance:
The molar mass of a substance ($ M $) is the mass (in grams) of one mole of molecules or structural units of that substance!
The molar masses of substances are calculated by summing the atomic masses of the → periodic table .
Relationship between mass ($ m $ in g), molar mass $ M $ and number of moles $ n $
$ n $ $ = $ $ \frac{m}{M} $
Calculate the mass of oxygen present in $ 3.0\; mol$ of carbon dioxide $CO_2$.
For answers, use (possibly several times) the arrows ↑ Down! and ↓ Up!
Complete please this question before moving on to the next one!
$3.0\;mol $ of carbon dioxide contain $6.0\; mol$ oxygen (atoms).
(Compare: 3 dozen bikes have 6 dozen wheels !)
Mass of oxygen=
$m$ $ = $ $n\cdot M_{O}$ $=$ $6.0\cdot 16.0$ $=$ $96\;g$
