1 GENERAL TYPES OF REACTIONS 1 Combination A B C two or more substances react two form a single substance a formation reactions elements compound 4 Fe s 3 O2 g 2 Fe2O3 s 8 C s 9 H2 g C8H18 l b hydration reactions addition of water CaO s H2O l Ca OH 2 s CaO lime when heated emits a very bright white light limelight Ca OH 2 hydrated lime is added to plaster to make it harder P2O5 s 3 H2O l 2 H3PO4 aq P2O5 is a very effective dehydration agent 2 Combustion combination with O2 as in burning fuel products are CO2 H2O and N2 2 C8H18 l 25 O2 g 16 CO2 g 18 H2O g 2 2 4 trimethylpentane isooctane is the major component of gasoline 4 CH3 3N l 21 O2 g 12 CO2 g 18 H2O g 4 N2 g Trimethylamine is responsible for the smell of rotten fish 3 Decomposition A B C one substance decomposing into two or more substances a decomposition of carbonates CaCO3 s CaO s CO2 g Calcium carbonate is the major component of seashells and egg shells b decomposition of chlorates and perchlorates 2 NaClO3 s 2 NaCl s 3 O2 g Fe ClO4 3 s FeCl3 s 6 O2 g Sodium chlorate is used in the manufacture of bleach sodium hypochlorite NaClO c decomposition of sulfites Na2SO3 s Na2O s SO2 g Sodium sulfite is added to wine to stop the fermentation process and to help preserve the wine d many others 4 Single replacement reactions 2 when a metal ion in a compound is replaced with another metal ion SnSO4 aq Ni s NiSO4 aq Sn s Tin bonds with iron very well and helps prevent the corrosion of iron Tin cans are steel iron with thin covering of tin 3 AgNO3 aq Cr s Cr NO3 3 aq 3 Ag s Chromium is added to iron to make stainless steel 5 Metathesis double replacement reactions cations and anions in two ionic compounds switch places Na2SO4 aq Ba C2H3O2 2 aq BaSO4 s 2 NaC2H3O2 aq Barium sulfate is ingested by X ray patients to improve the visibility of GI tract to X ray radiation Pb ClO3 2 aq 2 KCl aq PbCl2 s 2 KClO3 aq Lead II chloride combined with lead II hydroxide is used as a white paint pigment 6 Addition combination reaction where a substance is added to a compound with a double bond H H H C C C H H2O H H H C C H C C H HCl H H C H C C C H O H H C H H2 H H H H H C C C C H Cl H H H H H H H H H H H H C C H H H 3 7 Substitution an atom or a functional group in molecule in substituted for another atom or functional group H H C OH I H H H H O C C Cl H O H H C C H C C H H C O HNO3 H H H C C C H H H H O C C H H H H H O C C I H H H H C C C H H H H C C C C H H H H H H2O C O C N H O H HCl 4 8 Elimination decomposition reaction where a double bond is created H H H H C C O H H H H C C H H H2O when water is a product the reaction is also known as a dehydration reaction H H H C C C H H H Br H H H H C C C C H H H C C C H O H C C H H H H H H H C C C C H HBr H H H H C H O H H H H O O H C C C H H H THE AQUEOUS PHASE Q What happens to salt when it is dissolved in water It is a physical change but how can that be A i Solid salt is a collection of ions Na and Cl assembled in a lattice Ions are surrounded by each other ii When dissolved the ions are surrounded by water Thus the ions themselves don t change only their environment H O H O H O H H O H ion surrounded by other ions H H ion surrounded by water molecules solvent cage H 5 Ions or sometimes molecules that are surrounded by water are in the aqueous phase Ionic compounds which are soluble that is dissolve in water dissociate that is break apart into dissolved cations and anions Examples NaCl aq Na aq Cl aq K2O aq 2 K aq O2 aq note 2 K ions dissociate for every K2O unit Ca NO3 2 aq Ca2 aq 2 NO3 aq ions dissociate but polyatomic ions remain covalently bonded Fe2 SO4 3 aq Cs3PO4 aq Not all compounds dissociate into ions when in the aqueous phase as we shall soon see Aside phases of reactants and products g gas l liquid s solid aq aqueous TYPES OF SOLUTES 1 electrolytes when dissolved solution conducts electricity H2O without ions is a poor conductor are ionic compounds or acids usually a strong electrolytes Ions completely dissociate from formula unit or lattice NaCl aq Na aq Cl aq Water surrounds ions to dissolve lattice b weak electrolytes Ions partially dissociate from formula unit HC2H3O2 l H2O l HC2H3O2 aq H aq C2H3O2 aq a lot a little a little Equilibrium balance exists between dissociated ions and undissociated compounds More in 1190 2 nonelectrolytes when dissolved solution is still electrical insulator usually molecular compounds C12H22O11 s H2O l C12H22O11 aq 6 Subtle point Relatively insoluble compounds can be strong electrolytes ACIDS BASES AND SALTS Water H2O is made of two ions H aq hydrogen ion OH aq hydroxide ion Acids substances that increase H aq conc Strong acids strong electrolytes i e completely dissociate HCl aq H aq Cl aq memorize list HCl HBr HI HNO3 H2SO4 HClO3 HClO4 Weak acids weak electrolytes HF aq H aq F aq HF aq HF aq H aq F aq a lot a little a little H3PO4 aq H aq H2PO4 aq Bases substances that increase OH concentration Strong bases strong electrolytes all alkali metal hydroxides LiOH NaOH KOH RbOH CsOH some alkaline earth metal hydroxides Ca OH 2 Sr OH 2 Ba OH 2 Weak bases weak electrolytes usually increase OH aq conc indirectly by decreasing H aq conc NH3 aq H2O l NH4 aq OH aq C5H5N aq H2O l C5H5NH aq OH aq Neutralization reaction Acid Base Water Salt Salt ionic compound cations and anions remaining after water is made HNO3 aq KOH aq H2O l KNO3 aq 7 IONIC EQUATIONS molecular equations where all ions in aqueous solution are written in dissociated form NET IONIC EQUATIONS ionic equations where spectator ions ions unchanged in reaction are not included Example Molecular Equation 2 KBr aq Pb NO3 2 aq 2 KNO3 aq PbBr2 …