Chemical Reactions in Solution
Solubility rules, electrolytes, dissociation, ionic equations, and the aqueous reaction types.
Solubility rules
REFERENCESoluble: Group 1 & NH₄⁺ salts; NO₃⁻, acetate, ClO₃⁻, ClO₄⁻; most Cl⁻/Br⁻/I⁻ (except Ag⁺, Pb²⁺, Hg₂²⁺); most SO₄²⁻ (except Ba²⁺, Sr²⁺, Pb²⁺, often Ca²⁺). Insoluble: carbonates, phosphates, chromates, sulfides, most hydroxides, except with Group 1 / NH₄⁺ (Ba(OH)₂ is the common soluble exception).
Electrolyte classes
CORE RULEStrong: soluble ionic salts, strong acids, strong bases (fully ionize). Weak: weak acids/bases (partial). Nonelectrolyte: molecular substances that don't ionize.
Writing dissociation
CORE RULEAcids release H⁺: strong acids use a single arrow, weak acids an equilibrium arrow; polyprotic acids dissociate one proton at a time.
Salts split into cation + anion in stoichiometric ratio; polyatomic ions stay intact and Hg(I) is Hg₂²⁺. Insoluble salts do not dissociate.
Molecular → ionic → net ionic
METHODMolecular: intact formulas. Complete ionic: split ONLY soluble strong electrolytes; keep solids, liquids, gases, weak electrolytes, and covalent species intact.
Net ionic: cancel spectator ions (unchanged on both sides); show only species that actually change.
Precipitation
CORE RULEExchange the ions of two aqueous reactants; if a candidate product is insoluble by the rules, write it as a solid precipitate.
Acid-base neutralization
CORE RULEStrong acid + strong base net ionic: H⁺ + OH⁻ → H₂O. The driving force is water formation.
Gas-forming reactions
CORE RULECarbonate/bicarbonate + acid → CO₂ + H₂O (via H₂CO₃). Sulfite/bisulfite + acid → SO₂ + H₂O (via H₂SO₃). Ammonium salt + strong base → NH₃ + H₂O.
Aqueous reaction types
CORE RULEPrecipitation, acid-base, gas-forming, redox (recognition only here; oxidation numbers are Topic 7), or no reaction.
When to write 'no reaction'
WATCH OUTIf all possible products stay soluble strong electrolytes and no gas, precipitate, water, or weak electrolyte forms, it is no reaction.