3.2.1 Moles (HT only)
Moles
Avogadro constant = 6.02 × 1023
No of molecules = mole × 6.02 × 1023
Mass of 1 mol of a substance
= relative atomic mass (Ar) in grams if substance is an element
= relative formula mass (Mr) in grams if substance is a compound
Reacting masses
Eg If I react 10g of CaCO3 with excess HCl, what mass of CaCl2 should I produce?
CaCO3 + 2HCl → CaCl2 + CO2 + H2O
3.2.2 Amounts of substances in equations (HT only)
(Linked to other sub-topics)
3.2.3 Using moles to balance equations (HT only)
(Linked to other sub-topics)
3.2.4 Limiting reactants (HT only)
Mr of TiCl4 = 190
Na is in excess as n(Na) = 870 mol is more than 844 mol needed or n(TiCl4) = 211 mol is less than 217.5 mol needed
3.2.5 Concentration of solutions
(See 3.4 Using concentrations of solutions in mol/dm3 (chemistry only) (HT only))