11.1 Describing Chem Rxns How to write a word equation Reactants on left separated with + signs yields () Products separated with + Carbon and oxygen  Carbon Dioxide How to write a skeleton equation (pg323) Write formulas for reactants on left yields the formulas for products on right C + O  CO2 Steps for writing a balanced equation Pg 327 Skeleton equation plus coefficients to balance # of atoms C + 2O  CO2

11.2 Types of Chem Rxns 5 types of rxns Combination- 2 or more substances react to form 1 new substance; 2K+Cl22KCl; (R+SRS; 2 reactants are elements/ compounds make single compound) Decomposition- 1 compound breaks down into 2 or more simpler products; 2H2O H2+O2 ; (RSR+S; compound breaks down into 2 products) Single-replacement- 1 element replaces another element in compound; Zn+H2SO4ZnSO4 +H2 ; (T+RSTS+R; reactants are an element and compound products new compound and other element)

11.2 continued Double-replacement-exchange of +ions; one of following is true-1one product slightly soluble and make precipitate, 2- one product is gas, 3-one product is a molecular compound like water (R+S- + T+U-R+U- + T+S- ; reactants 2 ionic compounds products are two new compounds Combustion-reacts with oxygen to product heat and light; CxHy + (x+y/4) O2 xCO2 + (y/2)H20; CH4+2O2CO2+ 2H20

11.3 Rxns in Aqueous Solutions Net ionic equation Complete ionic equation: shows dissolved ionic compounds and dissociated free ions; can be “simplified” if unchanged from reactant to product Spectator ion: reactant and products not directly involved in reaction Net ionic equation: removes spectator ions; only reactants/ products directly related to chem change Ex: Ca2-(aq)+OH-(aq) +H+(aq)+PO43-(aq) Ca2+(aq)+PO43-(aq) +H20 (l) Net ionic= OH-(aq) + H+(aq) H20 (l) Formation of a precipitate in double-replacement rxn use “rules” for solubility Pg 344 Table 11.3

Summary 4 sentence summary of important concepts in chemical reactions