1
The Avogadro constant
One mole contains exactly entities. This value is exact: since the 2019 SI revision it defines the mole rather than being measured.
High school12 min
The mole and amount of substance
The four relations that give an amount of substance, how to pick the right one, and the unit traps that cost the most marks.
The essentials
2
The four relations
Members only
3
Molecular molar mass
Members only
4
Molar volume of a gas
Members only