chem reactions

• Synthesis

  • A + X → AX
  • A and X can be elements or simple compounds
  • AX is a compound
  • element + oxygen → oxide of element
  • metals + sulfur → sulfides
  • nonmetals + oxygen → oxides
  • oxides of active metals + water → metal hydroxides

• Decomposition

  • AX → A + X
  • electrolysis - decomposition of water using electricity
  • exceptions
  • metal carbonate → metal oxide + carbon dioxide
  • metal hydroxide → metal oxide + water vapor
  • metal chlorate → metal chloride + oxygen gas

• Single Replacement

  • A + BX → AX + B where A+B are metals
  • Y + BX → BY + X where Y+X are nonmetals
  • reactivity
  • group 1A increases ↓
  • halogens decreases ↓
  • most active metals + water → metal hydroxide + hydrogen gas
  • less active metals + steam → metal oxide + hydrogen gas
  • more reactive metals + some acids

• Double Displacement

  • AX + BY → AY + BX
  • one compound produced:
  • precipitate
  • insoluble gas
  • molecular compound (usually water)
  • other compound usually aqueous

• Combustion

  • Cx + Hy + O2 → CO2 + H2O

• Identification

  1. only one reactant? → decomposition
  2. reactants two elements / simple compounds? → synthesis
  3. reactants oxygen + hydrocarbon? → combustion
  4. reactants element + compound (not hydrocarbon) → single
  5. reactants two compounds composed of ions? → double

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