Section 01
The mole
One mole = 6.022 × 10²³ particles (Avogadro's number). The mole lets you convert between the microscopic and macroscopic worlds. Molar mass (g/mol) equals the sum of atomic masses in a formula.
Section 02
Mole ratios
Balanced equations give you the ratio of moles of each reactant and product. From grams → moles → moles → grams, stoichiometry solves quantity problems.
Section 03
Limiting reagent
The reactant that runs out first is the limiting reagent — it caps how much product you can make. Any leftover of the other reactant is called excess.