Lesson 2 of 3

The Mole and Stoichiometry

Master the mole concept and perform stoichiometric calculations.

Core52 min

The Mole

Just as a dozen = 12, a mole = $6.022 imes 10^{23}$ particles (atoms, molecules, ions, etc.)

$ext{moles} = rac{ ext{mass (g)}}{ ext{molar mass (g/mol)}}$

$ext{particles} = ext{moles} imes 6.022 imes 10^{23}$

15 min · watch

Learn why chemists use the mole as a counting unit.

12 min · read

$ext{moles} = rac{ ext{grams}}{ ext{molar mass}}$

$ext{particles} = ext{moles} imes 6.022 imes 10^{23}$

$rac{ ext{moles A}}{ ext{coefficient A}} = rac{ ext{moles B}}{ ext{coefficient B}}$

18 min · practice

Practice conversions with instant feedback!

7 min · quiz

Question

How many moles are in 18 grams of water ( $\text{H}_2\text{O}$ , molar mass = 18 g/mol)?

Conversion Pathways

Grams $leftrightarrow$ Moles: use molar mass

ext{moles} = rac{ ext{grams}}{ ext{molar mass}}

Moles $leftrightarrow$ Particles: use Avogadro's number

ext{particles} = ext{moles} imes 6.022 imes 10^{23}

Mole ratios: from coefficients in balanced equation

rac{ ext{moles A}}{ ext{coefficient A}} = rac{ ext{moles B}}{ ext{coefficient B}}