Relative formula mass (Mr) = sum of all Ar values. One mole = Mr in grams = 6.02 × 1023 particles.
Moles = massMr. Mass = moles × Mr.
Concentration (mol/dm3) = molesvolume (dm3). Remember: 1 dm3 = 1000 cm3.
From balanced equations: use mole ratios to find unknown quantities. Steps: mass → moles → ratio → moles → mass.