Chemistry : Chemical Reactions

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What is a Chemical Reaction ?

A chemical reaction is a chemical change where matter (a reactant or reactants) gets converted into a new substance or subtances (a product or products). Some reactions occur only under certain conditions (e.g., supply of heat; presence of light or electricity). Some reactions are accompanied by certain external indications (e.g., color change; evolution of gas, heat or light).

What are Some Important Types of Chemical Reactions ?

• Synthesis or Direct Combination Reaction is a reaction where two or more substances directly combine to form a new chemical compound.
  General Form: A + B → AB
  Example: Fe + S → FeS
  i.e., Iron + Sulfur → Iron sulfide
• Decomposition Reaction is a reaction where a chemical compound breaks up (decomposes) into two or more substances.
  General Form: AB → A + B
  Example: ZnCO₃ → ZnO + CO₂
  i.e., Zinc carbonate (+ Heat) → Zinc oxide + Carbon dioxide
• Simple Displacement Reaction is a reaction where one element replaces another in a chemical compound to produce a new compound and the displaced element.
  General Form: A + BC → AC + B
  Example: Fe + CuSO₄ → FeSO₄ + Cu
  i.e., Iron + Copper Sulfate → Iron sulfate + Copper
• Double Decomposition Reaction is a reaction where two chemical compounds exchange their radicals to form two new compounds.
  General Form: AB + CD → AD + CB
  Example: KCl + AgNO₃ → KNO₃ + AgCl
  i.e., Potassium chloride + Silver nitrate → Potassium nitrate + Silver chloride

Practice Exercise for Chemistry Module on Types of Chemical Reactions

Practice Exercise for Chemistry Module on Experiments with Chemical Reactions