Chem Reactions

• Combination (or synthesis) reaction:

  • Definition: two or more substances combine to form a single new substance
  • General form: A + B → AB
  • Example: Sodium metal reacts with chlorine gas to produce sodium chloride: 2Na + Cl2 → 2NaCl
• Decomposition reaction:

  • Definition: a compound breaks down into two or more simpler substances
  • General form: AB → A + B
  • Example: Calcium carbonate decomposes into calcium oxide and carbon dioxide: CaCO3 → CaO + CO2
• Single displacement reaction:

  • Definition: one element replaces a similar element in a compound
  • General form: A + BC → AC + B
  • Example: Zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen: Zn + 2HCl → ZnCl2 + H2
• Double displacement reaction:

  • Definition: two substances of two compounds exchange places to form two new compounds
  • General form: AB + CD → AD + CB
  • Example: Sodium sulfide reacts with hydrochloric acid to form sodium chloride and hydrogen sulfide: Na2S + 2HCl → 2NaCl + H2S
• Combustion reaction:

  • Definition: a substance reacts with oxygen gas, releasing energy in the form of light and heat
  • Combustion reactions must involve oxygen, O2 as one reactant
  • Example: The combustion of sugar produces water vapor and carbon dioxide: C6H12O6 + 6O2 → 6CO2 + 6H2O