Moles and molar mass form the backbone of stoichiometry.
The mole concept allows you to translate between the mass of a substance and the number of particles it contains.
You use Avogadro’s number, 6.022 × 1023 mol^−1, to connect these realms: one mole of any substance contains that many particles, whether atoms, molecules, or ions.
The mechanism here is dimensional analysis.
You convert grams to moles using the molar mass, then moles to particles using Avogadro's number.
The equation n = m/M is your tool: n is the number of moles, m is the mass in grams, and M is the molar mass in grams per mole.
The trap is losing track of units or misapplying Avogadro’s number to masses instead of moles.
Confusing molar mass with molecular mass or atomic mass is another common error.
Treat moles as a bridge between the macroscopic and atomic worlds, not just a step in calculations.