Reaction Types
What to know
Classify reactions and predict products. The main categories: synthesis (A + B → AB), decomposition (AB → A + B), single replacement (A + BC → AC + B, driven by activity series), double replacement/precipitation (AB + CD → AD + CB, driven by formation of a solid, gas, or water), combustion (hydrocarbon + O2 → CO2 + H2O), and acid–base neutralization (acid + base → salt + water). Also recognize redox reactions by changes in oxidation state, and identify oxidizing and reducing agents.
Know solubility rules to predict precipitates, and the activity series to decide whether a metal displaces another. Recognize common gas-forming reactions (carbonates with acid give CO2; sulfites give SO2; ammonium salts with base give NH3). Balance charges in ionic equations and know the difference between molecular, complete ionic, and net ionic equations-spectator ions cancel.
Traps
- Writing a single-replacement reaction that cannot occur because the free metal is less reactive than the one in solution.
- Forgetting to balance atoms and charge.
- Misidentifying the precipitate when both products are soluble (no reaction).
- Confusing oxidation (loss of electrons) with reduction (gain of electrons)-remember OIL RIG.
Worked example
Predict products of AgNO3(aq) + NaCl(aq). Swap ions: AgCl and NaNO3. Solubility rules say AgCl is insoluble, NaNO3 is soluble. Net ionic equation: Ag⁺(aq) + Cl⁻(aq) → AgCl(s). Rule: if all possible products are soluble, no reaction occurs.