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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