Chemistry · Grades 9–12
Moles, mass and particle counts · Revision sheet
Keep molar mass, mass and amount as different quantities.
Learn the idea
Amount
The mole counts entities. Specify atoms, molecules, ions or formula units.
Mass rule
n = m/M, where mass m and molar mass M use compatible units.
Particles
N = nNₐ. Use a stated rounded value of Avogadro’s constant consistently.
Interpretation
Equal amounts in moles contain equal numbers of the specified entities, not necessarily equal masses.
Explain without looking
- A 15 g sample contains 0.5 mol. What is its molar mass?
- Explain why a larger molar mass does not mean more molecules in one mole.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.