Chemical Reactions The 5 Basic Classifications

SYNTHESIS A reaction in which two or more reactants yield a single product. Also called composition or combination General Equation A + B  AB EX: 2 Li + Se ---> Li 2 Se

Decomposition Reaction One Reactant Breaking Down into two or more products General Equation AB ---> A + B Example: 2 HgO  2 Hg + O 2

One or more reactants combine with oxygen releasing heat or light One or more reactants combine with oxygen releasing heat or light Any combustion reaction must include the reactant oxygen, O 2 General Equation: A + O 2  AO Example: Example: 2Mg(s) + O 2 (g) 2MgO(s) What Is Combustion?

Single Replacement Sometimes called Displacement Sometimes called Displacement One element replaces a similar element in a compound One element replaces a similar element in a compound A + BX  AX + B 2 Na + 2 HOH ----> 2 NaOH + H 2

Double Replacement Reaction that has the interchanging of two ions from two different compounds. Reaction that has the interchanging of two ions from two different compounds. general form: general form: AB + CD----> AD + CB Example: Example: Pb(NO 3 ) KI ----> PbI KNO 3

Double Replacement Equation consists of two reactants that have both a cation and anion. During a reaction the cations (or anions) switch places. The products usually consist of a precipitate.

Reaction Checklist 1) Is O 2 a reactant? (combustion) 2) One product? (synthesis) 3) One reactant? (decomposition) 4) Is an element being replaced? (single) 5) 2 switches? (double) NEXT WEEK: STOICHIOMETRY!!!!