Types of Chemical Reactions

Combination Reactions (Synthesis)

  • A chemical reaction where two or more reactants come together to form one product.

  • Combination reactions are unique because they have two or more reactants and one product.

  • A + B 🡪 AB

Example:  2Mg (s) + O2 (g) 🡪 2MgO (s)

Decomposition Reactions

  • A chemical reaction where a single compound breaks down into two or more simpler products

  • Decomposition reactions are unique because the have one reactant and two products.

  • Require some form of energy to break the initial compound

  • XY           X+ Y

Example:  2HgO (s)           2Hg (l) + O2 (g)

Single Replacement Reactions

  • A chemical reaction where one element replaces a second element in a compound 

  • Single replacement reactions have products and reactants consisting of one element and one compound and the switch of one element for another in a compound

  • C + DE 🡪 CE + D


Example:  Zn (s) + Cu(NO3)2 (aq) 🡪Cu (s) + Zn(NO3)2 (aq)

Double-Replacement Reactions

  • A chemical change involving an exchange of positive ions between two compounds 

  • Generally take place in aqueous solutions

  • This can only occur if one of the product is only slightly soluble and forms a ppt, one product is a gas, or one product is a molecular compound. 

  • Double-replacement reactions have the above products and switching of two cations. 

  • AB + XY 🡪 XB + AY

Example:  Na2S(aq) + Cd(NO3)2 (aq) 🡪 CdS (s) + 2NaNO3

Combustion Reactions

  • The chemical reaction of a carbon-based compound with oxygen that produces carbon dioxide and water vapor

  • Used to produce energy, like in power plants

  • Combustion reactions have production of CO2 (g) and H2O (g) and a reaction with O2 (g). 

C2H2 (g)+ O2 (g) 🡪 CO2 (g) + H2O (g)