The mole concept, finally intuitive
A mole is just a counting unit. Once conversions between mass, moles and particles are automatic, most of chemistry gets easier.
What this covers
- Avogadro's number
- Molar mass from the periodic table
- Mass ↔ moles ↔ particles
- Concentration in mol/dm³
- Molar gas volume
Worked example
Problem
How many moles are in 25 g of CaCO₃?
- 1Molar massCa 40 + C 12 + (O 16 × 3) = 100 g/mol.
- 2Dividen = m/M = 25 / 100.
Answer: 0.25 mol
Mistakes that cost marks
- Forgetting subscripts when computing molar mass.
- Multiplying instead of dividing by molar mass.
- Mixing cm³ and dm³ in concentration calculations.
Questions students ask
Why do chemists use moles at all?
Because reactions happen in particle ratios, and moles convert weighable mass into particle counts.
Practise quantitative chemistry until it sticks
Noeta remembers every step you missed and brings it back right before you forget it — 10 free questions a day, no card required.
Start free