Chemical Reactions Reaction Types

Most chemical reactions can be classified as one of five general types.

Direct Combination Reaction (Synthesis)  Two or more reactants come together to form a single product.  A + B  AB  Letters A and B stand for either elements or compounds, and AB stands for a compound consisting of A and B

2Na + Cl 2  2NaCl Two or more reactants Only one product (Compound)

Combustion CH 4 + 2O 2  CO 2 + 2H 2 O Element or Compound The element Oxygen is a reactant Oxide is a product O2O2

Decomposition Reaction  A single compound is broken down into two or more smaller compounds or elements.  AB  A + B

2H 2 O  2H 2 + O 2 Only one Reactant (compound) Two or more products

Single Replacement Reaction (Displacement)  An uncombined element displaces an element that is part of a compound  A + BX  AX + B  BX and AX are usually ionic

Mg + CuSO 4  MgSO 4 + Cu Single Element Compound Single Element

Double Replacement Reaction (Displacement)  Atoms or ions from two different compounds replace each other.  AX + BY  BX + AY

CaCO 3 + 2HCl  H 2 CO 3 + CaCl 2 Compounds Elements or ions in each compound trade places