Classifying chemical reactions Why? • When we classify, we are able to organize information and understand the material better. Quick review: Symbolizing chemical reactions coefficients reactants products 5 Classes of Chemical Reactions 1. 2. 3. 4. 5. Synthesis: To make Decomposition: To break down Single replacement: Single Substitute Double replacement: Two substitutes Combustion: To burn 1. Synthesis Reactions How do we recognize a synthesis reaction? a. A single product forms from two or more reactants. Example: 2 MgO 2 Mg + __ O2 __ __ General format: A + B AB How does this cartoon symbolize a synthesis reaction? A B AB Indicate which letter each animal represents. Synthesis reaction demonstration 2. Decomposition Reaction How do we recognize a decomposition reaction? a. A reactant breaks down into two or more products Example: H2O2 H2O + O2 General Format: AB A + B How does this cartoon symbolize a decomposition reaction? AB A B Indicate which letter each figure represents. Decomposition example 2 Na + __Cl 2 __NaCl __ 2 3. Single Replacement Reactions How do we recognize a single replacement reaction? a. A single element reacts with a compound b. Products are a different single element and a different compound Example: 2 HCl ---> __ ZnCl2 + __ H2 __ Zn + __ General format: A + BC AC +B How does this cartoon symbolize a single replacement reaction? A BC AC B Indicate which letter each figure represents. Single replacement reaction example 4. Double Replacement Reaction How do we recognize a double replacement reaction? a. Two compounds exchange partners and form two new compounds b. This reaction often produces a precipitate Example: 2 HCl ---> __ FeCl2 + __ H2S __ FeS + __ General format: AB + CD AD + CB How does this cartoon symbolize a double replacement reaction? A B C D C B A D Indicate which letter each figure represents. Example of a double replacement reaction 5. Combustion Reactions How do we recognize a combustion reaction? a. A compound containing CHO reacts with oxygen b. Products are carbon dioxide and water Example (combustion of ethanol): 1 CH3CH2OH + __ 3 O2 __ 2 CO2 +__ 3 H2 O __ General format: •CHO + O2 CO2 + H2O Example of a combustion reaction