Reactions in Aqueous Solutions, Predicting Products and Classifying Types of Chemical Reactions

I. Predicting Whether a Reaction Will Occur A. Four Driving Forces 1. Formation of a solid (precipitate) 2. Formation of water 3. Transfer of electrons 4. Formation of a gas B. If a driving force occurs the reaction will take place.

1. Soluble solid – readily dissolves in water 2. Insoluble and slightly soluble solid – a solid where such a tiny amount dissolves in water that it is undetectable to the naked eye 3. Solubility is temperature dependent State is aqueous - (aq) State is solid - (s) Predicting States of Substances States of reactants can be manipulated

Solubility Rules (on snoopy sheet) Ex. Predict whether the following substances are soluble or insoluble. AgNO 3 Al(OH) 3 Cu 3 PO 4 Li 2 CO 3 ZnSO 4 (aq) (s) Solubility Rules Mainly water soluble (aq) All nitrates are soluble. All acetates are soluble. All chlorates are soluble. All chlorides are soluble except AgCl, Hg 2 Cl 2, and PbCl 2 All bromides are soluble except AgBr, Hg 2 Br 2, PbBr 2, and HgBr 2 All iodides are soluble except AgI, Hg 2 I 2, PbI 2, and HgI 2 All sulfates are soluble except CaSO 4, SrSO 4, BaSO 4, PbSO 4, Hg 2 SO 4, and Ag 2 SO 4 Mainly water insoluble (s) All sulfides are insoluble except those of 1A and 2A elements and (NH 4 ) 2 S All carbonates are insoluble except those of 1A and (NH 4 ) 2 CO 3 All phosphates are insoluble except those of 1A and (NH 4 ) 3 PO 4 All hydroxides are insoluble except those of 1A, Ba(OH) 2, Sr(OH) 2 and Ca(OH) 2

When a soluble ionic salt dissolves in water the ions separate and a hydration shell is formed around each ion (Dissociation) Ex. Ba(NO 3 ) 2 in water – Ba(NO 3 ) 2 (aq)  Ba +2 (aq) + 2 NO 3 -1 (aq) Al(C 2 H 3 O 2 ) 3 (aq)  Al +3 (aq) + 3 C 2 H 3 O 2 -1 (aq) Al 2 (CO 3 ) 3 (s)  Al 2 (CO 3 ) 3 (s) or No RXN Aluminum acetate Aluminum carbonate

Draw a beaker of dissociated sodium chloride; a beaker of dissociated Aluminum nitrate; and a beaker of silver chloride. Na + 1 Cl -1 Na +1 Cl -1 Na +1 = sodium ion = chloride ion Al +3 NO 3 -1 Al +3 NO 3 -1 = aluminum ion = nitrate ion Cl -1 Ag +1 Cl -1 Ag +1 Cl -1 Ag +1 = silver ion = chloride ion

Special Rules 1. Acids are aqueous 2. Most metal oxides are solids 3. Most non-metal oxides are gases

III. Types of Reactions Double Displacement: Single Displacement: Decomposition:Synthesis:Combustion: AB  A + B AB +YZ  AZ + YB A +YB  Y + AB A + B  AB C x H x + O 2  CO 2 + H 2 O Reactants are: 2 compounds Reactants are: 1 element & 1 Compound Reactant is: 1 compound Reactants are: 2 elements or 2 oxides Reactants are: h ydrocarbon and oxygen

IV. Predicting Products A. Double Displacement reactions: two compounds combine to produce two different compounds - Acid-Base and Precipitation Reactions. * Use solubility rules. General Equation: Example: AB + YZ  AZ + YB Lead (II) acetate + sodium chloride Pb(C 2 H 3 O 2 ) 2 (aq) + NaCl  PbCl 2 (s) + NaC 2 H 3 O 2 (aq) 22 Driving force = liquid Driving force = solid Pb +2 C 2 H 3 O 2 -1 Na +1 Cl -1

B.Single Replacement Reactions: Activity Series Single Displacement reactions: an element and a compound combine to form a new element and compound. * Use the activity series. General Equation: Example: A + YB  Y + AB (Cation)B + AZ  Z + AB (Anion) Sodium + Lead (II) acetate Na +1 Pb +2 C 2 H 3 O 2 -1 Na (s) + Pb(C 2 H 3 O 2 ) 2(aq)  Pb (s) + NaC 2 H 3 O 2 (aq) 22 *If you don’t know the charge use +2

Single Replacement Reactions: Activity Series Active metal elements can replace less active metals, active nonmetal elements can replace less active nonmetals. Active metal elements can replace less active metals, active nonmetal elements can replace less active nonmetals. Use the Activity series (snoopy sheet) to determine whether or not the reaction will occur. Use the Activity series (snoopy sheet) to determine whether or not the reaction will occur. Driving force is the transfer of electrons. Driving force is the transfer of electrons.

C. Decomposition reactions: a single compound is broken down into more than one product. There are six different types. 1. Decomposition of a binary compound into its elements. * Usually requires heat or electricity. General Equation: Example: 2. Decomposition of a base into a metal-oxide and water. General Equation: Example: AB  A + B Δ = heat or electricity Sodium Chloride NaCl (aq) + Na (s)  Cl 2(g) 22 AOH  AO + H 2 O Sodium Hydroxide NaOH (aq) +  H 2 O (l) 2 Base = Compound that contains hydroxide (OH -1 ) A is metal/cation, B is nonmetal/anion Na 2 O (s) Metal-oxide = solid

3. Decomposition of a ternary acid into a nonmetal-oxide and water. General Equation: Example: 4. Decomposition of a metallic carbonate into a metal-oxide and carbon dioxide. General Equation: Example: HBO  BO + H 2 O sulfuric acid H 2 SO 4(aq) +  H 2 O (l) ACO 3  AO + CO 2 Sodium Carbonate Na 2 CO 3(aq) +  CO 2(g) SO 3(g) nonmetal-oxide = gas Na 2 O (s) A is metal/cation, B is nonmetal/anion

5. Decomposition of a metallic chlorate into a metal-chloride and oxygen gas. 5. Decomposition of a metallic chlorate into a metal-chloride and oxygen gas. General Equation: Example: 6. Decomposition of a tertiary salt into a metal- oxide and a non-metal oxide General Equation: Example: AClO 3  ACl + O 2 Sodium Chlorate NaClO 3(aq) +  O 2(g) 22 ABO  AO+ BO Sodium Phosphate Na 3 PO 4(aq) +  P 2 O 5(g) 23 NaCl (aq) 3 Na 2 O (s) A is metal/cation, B is nonmetal/anion

Special Situations Whenever H 2 CO 3, H 2 SO 3, or NH 4 OH is a product it will decompose immediately as follows: Whenever H 2 CO 3, H 2 SO 3, or NH 4 OH is a product it will decompose immediately as follows: H 2 CO 3  H 2 O + CO 2 H 2 CO 3  H 2 O + CO 2 H 2 SO 3  H 2 O + SO 2 H 2 SO 3  H 2 O + SO 2 NH 4 OH  H 2 O + NH 3 NH 4 OH  H 2 O + NH 3

D. Synthesis reactions: two substances combine to form one product. There are four different types. 1. Two elements combine to form a binary compound. General Equation: Example: 2. Combining a metal-oxide and water to produce a base. General Equation: Example: A is metal/cation, B is nonmetal/anion A + B  AB Sodium + Chlorine NaCl (aq) + Na (s)  Cl 2(g) 22 AO + H 2 O  AOH Barium oxide + water Ba(OH) 2(aq) + BaO (s)  H 2 O (l)

3. Combining a nonmetal–oxide and water to produce a tertiary acid. General Equation: Example: 4. Combining a metal-oxide and a nonmetal- oxide to produce a tertiary salt. General Equation: Example: BO + H 2 O  HBO dinitrogen pentoxide + water HNO 3(aq) + N 2 O 5(g)  H 2 O (l) 2 AO + BO  ABO Barium oxide + dinitrogen pentoxide Ba(NO 3 ) 2(aq) + BaO (s)  N 2 O 5(g) A is metal/cation, B is nonmetal/anion

E. Combustion reactions: Certain organic compounds (Hydrocarbons – compound containing Carbon and Hydrogen or Carbon, Hydrogen and Oxygen) burn to produce specific products. There are two types. 1. Complete combustion – combining a hydrocarbon with excess oxygen to produce carbon dioxide and water. * if the equation does not indicate limited oxygen assume complete combustion General Equation: Example: 2. Incomplete combustion - combining a hydrocarbon with limited oxygen to produce carbon monoxide and water. General Equation: Example: C x H x + O 2  CO 2 + H 2 O C x H x + limited O 2  CO + H 2 O CH 4(g) + limited O 2(g)  CO (g) + CH 4(g) + O 2(g)  CO 2(g) +H 2 O (g) H 2 O (g)

F. Oxidation Reduction reactions: (redox) Driving Force = Transfer of electron Driving Force = Transfer of electron Always in single displacement reactions Always in single displacement reactions Sometimes in Synthesis and Decomposition Sometimes in Synthesis and Decomposition Never in Double Displacement Never in Double Displacement Example: Anytime a single element is present a reaction is also classified as redox NaCl (aq) +Na (s)  Cl 2(g) 22 NaCl (aq) +Na (s)  Cl 2(g) 22 Zn(NO 3 ) 2(aq) + 2 Na (s)  2NaNO 3(aq) + Zn (s) decomposition & redox synthesis & redox single displacement & redox