Types of Chemical Reactions

3/4/25 assignment for chemistry by Izzy Campbell

Combination Reaction (Synthesis)

• A 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 Reaction

• A 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 Reaction

• A 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 Reaction

• A chemical reaction with 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 Reaction

• A 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)