Types of Chemical Reactions

Chemical Reaction Types based on ∆ Energy Exothermic Endothermic

1) Exothermic – energy comes out of rxn (rxn gives off energy) Energy contained in chemical bonds is given off when the bonds are broken Forms of energy given off…. Heat, light, sound, electricity

2) Endothermic – energy goes into rxn. (rxn takes in energy) Absorbs energy and uses it to make chemical bonds Feels cold

Chemical Rxn Types Based on Products 1) Synthesis rxn – (combination rxn) Put small molecules together to make larger molecules Look for : more reactants than products Example: C + O2  CO2

2) Decomposition rxn – Take apart large molecules to get smaller molecules Look for : more products than reactants Example : H2CO3  H2O + CO2

3) Single Replacement rxn – A single pure element takes the place of a different pure element in a compound Look for : pure element as reactant and a different pure element as a product Example : Zn + H2(SO4)  H2(SO4) + H2

3) Double Replacement rxn – Two compounds trade cations Look for : 2 compounds as reactants and 2 different compounds as products Example : Mg(CO3) + HCl  MgCl + H(CO3)

Another example KCl + Pb(NO3) --> K(NO3) + PbCl

A Special Double Replacement Rxn = Neutralization Reactions Acid + Base  Salt + H2O Reactants : Acid + Base Products : Salt + H2O