Lesson 6 of 8
The Mole and Stoichiometry
Atoms are way too small to count one at a time, so chemists count them in big groups called moles, the same way you count eggs in dozens.
KEY TERM
A mole is a counting unit equal to Avogadro's number, which is 6.02 x 10^23 particles. One mole of anything contains that many particles.
Molar Mass
The molar mass of a substance is the mass of one mole of it, measured in grams. You find it by adding up the atomic masses from the periodic table. It lets you switch between grams and moles.
Mole Ratios (Kept Simple)
- ●A balanced equation tells you the ratio of moles between substances. The coefficients are the ratio.
- ●If an equation shows 2 H2 plus 1 O2 makes 2 H2O, then 2 moles of hydrogen react with 1 mole of oxygen.
- ●Stoichiometry just means using those mole ratios to figure out how much product you get or how much reactant you need.
REMEMBER
The mole is a bridge. Grams to moles to particles, all connected by molar mass and Avogadro's number.