Reactions in Aqueous Solutions, Predicting

Products and Classifying Types of Chemical

Reactions

I. Predicting Whether a Reaction Will Occur

A. Four Driving Forces1. Formation of a solid (precipitate)2. Formation of water3. Transfer of electrons4. 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.AgNO3

Al(OH)3

Cu3PO4

Li2CO3

ZnSO4

(aq)

(aq)

(aq)

(s)

(s)

Solubility RulesMainly water soluble (aq)All nitrates are soluble.All acetates are soluble.All chlorates are soluble.All chlorides are soluble except AgCl, Hg2Cl2,

and PbCl2All bromides are soluble except AgBr, Hg2Br2,

PbBr2, and HgBr2

All iodides are soluble except AgI, Hg2I2, PbI2, and HgI2

All sulfates are soluble except CaSO4, SrSO4, BaSO4, PbSO4, Hg2SO4, and Ag2SO4

Mainly water insoluble (s)All sulfides are insoluble except those of 1A

and 2A elements and (NH4)2SAll carbonates are insoluble except those of

1A and (NH4)2CO3

All phosphates are insoluble except those of 1A and (NH4)3PO4

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(NO3)2 in water – Ba(NO3)2 (aq) Ba+2

(aq) + 2 NO3-1

(aq)

Al(C2H3O2)3 (aq) Al+3(aq) + 3 C2H3O2

-1(aq)

Al2(CO3)3 (s) Al2(CO3)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

Na+1

Na+1

Na+1

Cl-1

Cl-1Cl-1

Cl-1

Cl-1Na+1

Cl-1

Na+1 = sodium ion

= chloride ion

Al+3

Al+3

NO3-1

NO3-1

NO3-1

NO3-1

NO3-1

NO3-1

Al+3

NO3-1

= aluminum ion

= nitrate ion

Cl-1

Ag+1 Cl-1Cl-1

Cl-1Ag+1

Ag+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

CxHx + O2 CO2 + H2O

Reactants are: 2 compounds

Reactants are: 1 element & 1 Compound

Reactant is: 1 compound

Reactants are: 2 elements or 2 oxides

Reactants are: hydrocarbon 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 chloridePb(C2H3O2)2 (aq)

+ NaCl(aq)

PbCl2 (s)+ NaC2H3O2 (aq)

2 2

Driving force = liquid

Driving force = solid

Pb+2 C2H3O2-1 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) acetateNa+1 Pb+2 C2H3O2

-1

Na(s) + Pb(C2H3O2)2(aq) Pb(s) + NaC2H3O2 (aq)2 2

*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.

Use the Activity series (snoopy sheet) to determine whether or not the reaction will occur.

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) Cl2(g)2 2

AOH AO + H2O

Sodium Hydroxide

NaOH(aq) + H2O (l)2

Base = Compound that contains hydroxide (OH-1)

A is metal/cation, B is nonmetal/anion

Na2O(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 + H2O

sulfuric acid

H2SO4(aq) + H2O (l)

ACO3 AO + CO2

Sodium Carbonate

Na2CO3(aq) + CO2(g)

SO3(g)

nonmetal-oxide = gas

Na2O (s)

A is metal/cation, B is nonmetal/anion

 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 oxideGeneral Equation: Example:

AClO3 ACl + O2

Sodium Chlorate

NaClO3(aq) + O2(g)2 2

ABO AO+ BO

Sodium Phosphate

Na3PO4(aq) + P2O5(g)2 3

NaCl (aq) 3

Na2O(s)

A is metal/cation, B is nonmetal/anion

Special Situations

Whenever H2CO3, H2SO3, or NH4OH is a product it will decompose immediately as follows:

H2CO3 H2O + CO2

H2SO3 H2O + SO2

NH4OH H2O + NH3

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) Cl2(g) 22

AO + H2O AOH

Barium oxide + water

Ba(OH)2(aq)+BaO(s) H2O(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 + H2O HBO

dinitrogen pentoxide + water

HNO3(aq)+N2O5(g) H2O(l) 2

AO + BO ABO

Barium oxide + dinitrogen pentoxide

Ba(NO3)2(aq)+BaO(s) N2O5(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:

CxHx + O2 CO2 + H2O

CxHx + limited O2 CO + H2O

CH4(g) + limited O2(g) CO(g) +

CH4(g) + O2(g) CO2(g) + H2O(g)

H2O(g)

22

2 423

F.     Oxidation Reduction reactions: (redox)

Driving Force = Transfer of electron Always in single displacement reactions Sometimes in Synthesis and Decomposition Never in Double Displacement

 Example:

Anytime a single element is present a reaction is also classified as redox

NaCl(aq) +Na(s) Cl2(g)2 2

NaCl(aq)+Na(s) Cl2(g) 22

Zn(NO3)2(aq) + 2 Na(s) 2NaNO3(aq) + Zn(s)

decomposition & redox

synthesis & redox

single displacement & redox