Oxidation Numbers, Oxidation Numbers, Reactions in Aqueous Reactions in Aqueous Solutions, & Predicting Solutions, & Predicting

ProductsProducts

I. Rules for Assigning Oxidation Numbers

1. The oxidation number of any uncombined element is 0. 2. The oxidation number of a monatomic ion equals the charge on the ion. 3. The more-electronegative element in a binary compound is assigned the number equal to the charge it would have if it were an ion. 4. The oxidation number of fluorine in a compound is always -1. 5. Oxygen has an oxidation number of -2 unless it is combined with F (when it is +2), or it is in a peroxide (such as H2O2 or Na2O2), when it is -1.

6. The oxidation state of hydrogen in most of its compounds is +1 unless it is combined with a metal, in which case it is -1.

Oxidation vs. ReductionOxidation vs. Reduction

The The sum of the oxidation states in a neutral sum of the oxidation states in a neutral compound mustcompound must equal zeroequal zero and and must be equal to must be equal to the overall charge in an ionic compoundthe overall charge in an ionic compound..

Assign oxidation states to each of the atoms in the following compounds:

a. FeF2 b. H2O c. KMnO4

d. C2H6 e. ICl5 f. SO42-

2(-1)1(+2) 1(-2)2(+1) 4(-2)1(+1) +7

6(+1)2(-3) 5(-1)+5 4(-2)+6

Fe = +2, F = -1

C = -3, H = +1

H = +1, O = -2 K = +1, Mn = +7, O = -2

I = +5, Cl = -1 S = +6, O = -2

Assign oxidation states to each atom in the equation. Fe2O3 + 2 Al Al2O3 + 2 Fe

0 0-2+3 -2+3Fe gains electrons. It has been REDUCED

Al lost electrons. It has been OXIDIZED

= -2

Remember LEO GER:Remember LEO GER: LOSE ELECTRONS OXIDATIONLOSE ELECTRONS OXIDATIONGAIN ELECTRONS REDUCTIONGAIN ELECTRONS REDUCTION

Something that is reduced is called an oxidizing agent.Something that is reduced is called an oxidizing agent.Something that is oxidized is called a reducing agent.Something that is oxidized is called a reducing agent.

For each reaction, identify that atoms that undergo reduction, or For each reaction, identify that atoms that undergo reduction, or oxidation.oxidation.

a.a. 2 H2 H22 (g)(g) + O + O22 (g)(g) 2 H 2 H22O O (g)(g)

b.b. Zn Zn (s)(s) + Cu + Cu2+2+ (aq)(aq) Zn Zn2+2+ (aq)(aq) + Cu + Cu (s)(s)

c.c. 2 AgCl 2 AgCl (s)(s) + H + H22 (g)(g) 2 H 2 H++ (aq)(aq) + 2 Ag + 2 Ag (s)(s) + 2 Cl + 2 Cl-- (aq)(aq)

d. 2 MnOd. 2 MnO44--(aq)(aq) + 16 H + 16 H++

(aq)(aq) + 5 C + 5 C22OO442-2-

(aq)(aq) 2 Mn 2 Mn2+2+(aq)(aq) + 10 CO + 10 CO2(g)2(g) + 8 + 8

HH22OO(l)(l)

0 0 -2+1

0 +2 +2 0

-1+1 0 +1 0 -1

-2+7 +1 -2+3 +2 -2+4 -2+1

oxidized: hydrogen (0 to +1)reduced: oxygen (0 to -2)

oxidized: zinc (0 to +2)reduced: copper (+2 to 0)

oxidized: hydrogen (0 to +1)reduced: silver (+1 to 0)

oxidized: carbon (+3 to +4)reduced: manganese (+7 to +2)

II. REDOX ReactionsII. REDOX Reactions

Learning CheckLearning Check

Assign oxidation states to each of the atoms in the following compounds:

a. SO2 b. S c. SO3

Assign oxidation states to each atom in the equation. Determine which element was oxidized and which was reduced.

2 Al + 3 CuCl2 2 AlCl3 + 3 Cu

When a soluble ionic salt dissolves in water the ions When a soluble ionic salt dissolves in water the ions separate and a hydration shell is formed around separate and a hydration shell is formed around each ion each ion (Dissociation)(Dissociation)

Ex. Ba(NOEx. Ba(NO33))22 in water – 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

III. DissociationIII. Dissociation

Draw a beaker of dissociated sodium chloride; Draw a beaker of dissociated sodium chloride; a beaker of dissociated Aluminum nitrate; a beaker of dissociated Aluminum nitrate;

and a beaker of silver chloride.and a beaker of silver chloride.

Na+1

Na+1

Cl-1Cl-1

Cl-1

Na+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

Learning checkLearning check

Write a dissociation equation for Write a dissociation equation for aluminum sulfatealuminum sulfate

Draw a beaker of dissociated Draw a beaker of dissociated aluminum sulfatealuminum sulfate

IV. Predicting ProductsIV. Predicting Products

A. Single Displacement reactionsA. Single Displacement reactions: : an element and a compound combine an element and a compound combine to form a new element and compound.to form a new element and compound.

* Use the activity series.* Use the activity series.

General Equation:General Equation:

  

Example: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 ReactionsSingle Replacement Reactions: : Activity Series Activity Series

Active metal elements can replace less Active metal elements can replace less active metals, active nonmetal elements active metals, active nonmetal elements can replace less active nonmetals.can replace less active nonmetals.

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

Driving force is the transfer of electrons.Driving force is the transfer of electrons.

Learning checkLearning check

Try these single displacement Try these single displacement reactions:reactions:

3. copper + silver nitrate3. copper + silver nitrate

4. bromine + sodium chloride4. bromine + sodium chloride

Lab – Metal Activity and Lab – Metal Activity and ReactivityReactivity

B. Double Displacement reactionsB. Double Displacement reactions: : two compounds combine to produce two compounds combine to produce two different compounds - two different compounds - Acid-Base Acid-Base

and Precipitation Reactions. and Precipitation Reactions.

* Use solubility rules.* Use solubility rules.

General Equation: General Equation:

Example: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

Learning checkLearning check

Try these double displacement Try these double displacement reactions:reactions: sodium sulfate + lead (II) nitratesodium sulfate + lead (II) nitrate

sulfuric acid + potassium sulfuric acid + potassium hydroxidehydroxide

Molecular EquationMolecular Equation: shows the complete formula : shows the complete formula of all reactants and productsof all reactants and products

Ex: Ex:

Complete Ionic EquationComplete Ionic Equation: represents aqueous : represents aqueous compounds as ionscompounds as ions

Ex:Ex:

Net Ionic EquationNet Ionic Equation: includes only those : includes only those components directly involved in the reaction. components directly involved in the reaction. Ions present on both sides on the equation and Ions present on both sides on the equation and do not participate directly in the reaction are do not participate directly in the reaction are called called Spectator IonsSpectator Ions

Ex:Ex:

Silver nitrate + barium chlorideAg+1 NO3

-1 Ba+2 Cl-1

AgClAgNO3 (aq)+ BaCl2 (aq)

(s)

+ Ba(NO3)2 (aq)2 2

Ag+1(aq)2 + + + + + 2NO3

-1(aq) Ba+2

(aq) 2Cl-1(aq) 2AgCl(s) Ba+2(aq) 2NO3

-1(aq)

2Ag+1(aq) + 2Cl-1(aq) 2AgCl(s)

Complete Ionic and Net Ionic Complete Ionic and Net Ionic EquationsEquations

Ex: Write the molecular, complete ionic Ex: Write the molecular, complete ionic and net ionic equations for the and net ionic equations for the following reaction.following reaction.

Sodium + Zinc NitrateSodium + Zinc NitrateZn+2 NO3

-1Na+1

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

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

-1(aq) Zn(s) + 2 Na+1

(aq) + 2 NO3-1

(aq)

Net – 2 Na(s) + Zn+2(aq) Zn(s) + 2 Na+1

(aq)

Complete -

C. Decomposition reactionsC. Decomposition reactions: a single compound : a single compound is broken down into more than one product. There is broken down into more than one product. There are six different types.are six different types.

1. Decomposition of a binary compound into its 1. Decomposition of a binary compound into its elements.elements.

* Usually requires heat or electricity.* Usually requires heat or electricity.

General Equation:General Equation:

  

Example:Example:

2. Decomposition of a base into a metal-oxide and water.2. Decomposition of a base into a metal-oxide and water.

General Equation:General Equation:

  

Example: 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 3. Decomposition of a ternary acid into a nonmetal-oxide and water.nonmetal-oxide and water.

General Equation:General Equation:  Example:Example:  4. Decomposition of a metallic carbonate 4. Decomposition of a metallic carbonate

into a metal-oxide and carbon dioxide.into a metal-oxide and carbon dioxide.General Equation:General Equation:  Example: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 5. Decomposition of a metallic chlorate into a metal-chloride and oxygen gas.a metal-chloride and oxygen gas.

General Equation:General Equation:  Example:Example:    6. Decomposition of a tertiary salt into a 6. Decomposition of a tertiary salt into a

metal-oxide and a non-metal oxidemetal-oxide and a non-metal oxideGeneral Equation:General Equation:  Example: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 SituationsSpecial Situations

Whenever HWhenever H22COCO33, H, H22SOSO33, or NH, or NH44OH is OH is a product it will decompose a product it will decompose immediately as follows:immediately as follows:

HH22COCO33 H H22O + COO + CO22

HH22SOSO33 H H22O + SOO + SO22

NHNH44OH OH H H22O + NHO + NH33

Learning checkLearning check

Try these decomposition reactions:Try these decomposition reactions:5. Calcium chlorate5. Calcium chlorate

6. Phosphoric acid6. Phosphoric acid

7. Barium hydroxide7. Barium hydroxide

8. Tin (IV) carbonate8. Tin (IV) carbonate

Synthesis reactionsSynthesis reactions: two substances : two substances combine to form one product. There are four combine to form one product. There are four

different types.different types. 1.1.            Two elements combine to form a binary compound.Two elements combine to form a binary compound.

General Equation:General Equation:

  

Example:Example:

  

  

2.2.          Combining a metal-oxide and water to produce a Combining a metal-oxide and water to produce a base.base.

General Equation:General Equation:

  

Example: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)

3.3.            Combining a nonmetal–oxide and water Combining a nonmetal–oxide and water to produce a tertiary acid.to produce a tertiary acid.

General Equation:General Equation:  Example:Example:    4.4.          Combining a metal-oxide and a Combining a metal-oxide and a

nonmetal-oxide to produce a tertiary salt.nonmetal-oxide to produce a tertiary salt.General Equation:General Equation:  Example: 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

Learning checkLearning check

Try these synthesis reactions:Try these synthesis reactions:9. Water + magnesium oxide9. Water + magnesium oxide

10. Water + dinitrogen trioxide10. Water + dinitrogen trioxide

11. Bromine + sodium11. Bromine + sodium

Combustion reactionsCombustion reactions: Certain organic compounds : Certain organic compounds (Hydrocarbons – compound containing Carbon and (Hydrocarbons – compound containing Carbon and Hydrogen or Carbon, Hydrogen and Oxygen) burn to Hydrogen or Carbon, Hydrogen and Oxygen) burn to produce specific products. There are two types.produce specific products. There are two types.

1.1.            Complete combustion – combining a hydrocarbon with Complete combustion – combining a hydrocarbon with excess oxygen to produce carbon dioxide and water.excess oxygen to produce carbon dioxide and water.

* if the equation does not indicate limited oxygen assume * if the equation does not indicate limited oxygen assume complete combustioncomplete combustion

General Equation:General Equation:  Example:Example:    2.2.          Incomplete combustion - combining a hydrocarbon with Incomplete combustion - combining a hydrocarbon with

limited oxygen to produce carbon monoxide and water.limited oxygen to produce carbon monoxide and water.General Equation:General Equation:  Example: 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

Learning checkLearning check

Try these combustion reactions:Try these combustion reactions:12. C12. C88HH1818 + oxygen + oxygen

13. C13. C22HH22 + oxygen + oxygen

Reaction rate depends on the collisions Reaction rate depends on the collisions between reacting particles.between reacting particles.

Successful collisions occur if the Successful collisions occur if the particles...particles... with each otherwith each other

have the correcthave the correct

have enough to break bondshave enough to break bonds

collide

orientation

kinetic energy

V. Reaction RatesV. Reaction Rates

To speed up the rate of the reaction:To speed up the rate of the reaction: Increase (smaller particles Increase (smaller particles

or dissolve in water)or dissolve in water)

Increase (add more reactant)Increase (add more reactant)

Increase (add heat source)Increase (add heat source)

AddAdd

surface area

concentration

temperature

catalyze/enzyme

ExothermicExothermic reactions release heat reactions release heat Heat is a productHeat is a product Feels hotFeels hot

EndothermicEndothermic reactions absorb heat reactions absorb heat Heat is a reactantHeat is a reactant Feels coldFeels cold

VI. Heat in ReactionsVI. Heat in Reactions