5 - 1CH110: Chapter 5 CH110 Chapter 5 Chemical Reactions Chemical Changes Chemical Equations Types...

5 - 1CH110: Chapter 5

CH110 Chapter 5CH110 Chapter 5Chemical ReactionsChemical Reactions

Chemical ChangesChemical Changes

Chemical EquationsChemical Equations

Types of ReactionsTypes of Reactions

Oxidation-ReductionOxidation-Reduction

MolesMoles

Energy in Chemical ReactionsEnergy in Chemical Reactions

Reaction RatesReaction Rates


What is Chemistry?What is Chemistry?““The study of The study of MatterMatter and its and its ChangesChanges.”.”

Physical ChangesPhysical Changes =

Changes in a Physical PropertyPhysical Property

Chemical ChangesChemical Changes =

Changes in a Chemical PropertyChemical Property

Appearance: Appearance: •melting, freezing, evaporation…melting, freezing, evaporation…•stretching, molding, cutting…stretching, molding, cutting…

Chemical Composition: Chemical Composition:


Change in the Chemical CompositionChange in the Chemical Composition

Burning of Magnesium

Chemical ChangesChemical Changes

Rusting of Iron

Decomposing of wood

Souring of Milk

Examples:Examples:


Chemical ReactionsChemical Reactions

• Color Color changechange

• Gas formedGas formed

• Solid precipitate formedSolid precipitate formed

• Temperature ChangeTemperature Change

• Gives heat = exothermicGives heat = exothermic

• Gets cold = endothermicGets cold = endothermic


Mg + O2 MgO +

Energy

Chemical Reactions Chemical Reactions

Shows how the Chemical change occurs.Shows how the Chemical change occurs.Shows how the Chemical change occurs.Shows how the Chemical change occurs.

ReactantsReactants

C3H8 + O2 CO2 + H2O + Energy

Fe + O2 Fe2O3

ProductsProductsProductsProducts


Chemical equationsChemical equations

Chemist’s shorthand to describe a reaction.

•ReactantsReactants •ProductsProducts

•The state of all substancesThe state of all substances

HH2 2 + O+ O22 HH22O + EO + E(g)(g) (g)(g) (g)(g)

•Any conditions Any conditions usedused in the reaction in the reaction

heatheat

•Same # & type atoms on each sideSame # & type atoms on each side• Law of Conservation of MatterLaw of Conservation of Matter

22 22

(g) (l) (s) (aq)(g) (l) (s) (aq)(g) (l) (s) (aq)(g) (l) (s) (aq)


Balancing EquationsBalancing Equations

___W10 + ___B8 ___WBWB___W10 + ___B8 ___WBWB


Making Hot dogs:How many packages wieners & buns to buy so none is left over.

44 55 4040


NaPO

MgCl


Na3PO4 + MgCl2 MgMg33(PO(PO44))22 + NaCl + NaCl Na3PO4 + MgCl2 MgMg33(PO(PO44))22 + NaCl + NaCl


Step 1Step 1: Count atoms of each element on both sides of equation.

31412

1 2831


NaPO

MgCl



•ReactantsReactants •ProductsProducts31412

1 2831

- - not balancednot balanced


Step 2Step 2: Determine which atoms are not balanced.





NaPO

MgCl




1 2831






Step 3: Step 3: Balance elements with #’s in front of formulas until all balanced.

(Never change the formulas!)(Never change the formulas!)


Hints:Hints:

•Start with a metal in a complex compound, or an element that only appears in one formula. (ie Mg here)

NaPO

MgCl




1 2831





- - not balancednot balanced66

66

6633

33

22

66

11

88

22

66


Hints:Hints:

•Start with an element that only appears in one formula on both sides of the equation.

•Leave oxygen until last.


C2H6 + O2 COCO22 + H + H22OOC2H6 + O2 COCO22 + H + H22OO

•ReactantsReactants •ProductsProductsC

H

O




C

H

O

C

H

O


Step 1Step 1: Count atoms of each element on both sides of equation.

2

6

2

2

6

2

1

2

3

1

2

3





2

6

2

2

6

2

1

2

3

1

2

3

Step 2Step 2: Determine which atoms are not balanced.



- - not balancednot balancedC

H

O

C

H

O


2

6

2

2

6

2




22



1

2

3

1

2

3


Step 3: Step 3: Balance one element at a time with coefficients in front of formulas until all balanced.

(Never change the formula!)(Never change the formula!)

22

55

33

66

77

3.53.5

77

C

H

O

C

H

O


C

H

O

C

H

O


22



2

6

2

2

6

2

1

2

3

1

2

3

22

55

33

66

77

3.53.5

77

Can’t have 3.5 O3.5 O22 , so multiply equation by 2!


3.53.5C2H6 + O2 COCO22 + H + H22OOC2H6 + O2 COCO22 + H + H22OO

22


C

H

O

C

H

O


2

6

2

2

6

2

1

2

3

1

2

3

44

55

66

66

77

77

77

Can’t have 3.5 O3.5 O22 , so multiply equation by 2!

22

44 44

1212 1212

1414 1414


Types of Chemical ReactionsTypes of Chemical Reactions

Complete:Complete:CC33HH8 8 + 5O+ 5O22 3CO 3CO22 + 4H + 4H22O O

CombustionCombustion

Incomplete:Incomplete:2C2C33HH8 8 + 7O+ 7O22 6CO + 8H 6CO + 8H22OO

CC33HH8 8 + 2O+ 2O22 3C + 4H 3C + 4H22O O


Types of Chemical ReactionsTypes of Chemical Reactions

CombinationCombination

DecompositionDecomposition

Single Replacement: Substitution Single Replacement: Substitution

Double Replacement: Metathesis Double Replacement: Metathesis

AA + + BBX X BB + + AAX X AA + + BBX X BB + + AAX X

A + B A + B C C A + B A + B C C

C C A + B A + B C C A + B A + B

AXAX + + BYBY BBXX + + AAYY AXAX + + BYBY BBXX + + AAYY


Combination ReactionsCombination Reactions

2H2H2 2 + O+ O22 2H 2H22O O

Formation of Acid RainFormation of Acid Rain

SO3 + H2O H2SO4SO3 + H2O H2SO4

Exposion of Hydrogen BalloonExposion of Hydrogen Balloon

Rusting of IronRusting of Iron

4 Fe + 3 O4 Fe + 3 O22 2 Fe 2 Fe22OO334 Fe + 3 O4 Fe + 3 O22 2 Fe 2 Fe22OO33

A + B A + B C C A + B A + B C C


Decomposition ReactionsDecomposition Reactions

Heating Egg ShellsHeating Egg Shells

CaCOCaCO3 3 CaO + CO CaO + CO22

2 H2 H22OO22 2 H 2 H22O + OO + O222 H2 H22OO22 2 H 2 H22O + OO + O22

Blood with Blood with peroxideperoxide

C C A + B A + B C C A + B A + B


Single Replacement Single Replacement ReactionsReactions

Iron Deposits on an Aluminum PanIron Deposits on an Aluminum Pan

Al + FeClAl + FeCl3 3 Fe + AlCl Fe + AlCl33 Al + FeClAl + FeCl3 3 Fe + AlCl Fe + AlCl33

AA + + BBX X BB + + AAX X AA + + BBX X BB + + AAX X


Activity series of metalsActivity series of metalspotassiumsodium

potassiumsodium

calciumcalcium

magnesiumaluminum

zincchromium

magnesiumaluminum

zincchromium

ironnickel

tinlead

ironnickel

tinlead

coppersilver

platinumgold

coppersilver

platinumgold

Hydrogen

Al + FeAl + Fe+3+3 Fe + Al Fe + Al+3+3Al + FeAl + Fe+3+3

Fe + Al Fe + Al+3+3

Fe + HFe + H++ Fe Fe+3+3 + H + H22 Fe + HFe + H++

Fe Fe+3+3 + H + H22

incr

easi

ng

rea

ctiv

ity

Element give e’s to ion

lower on list

Element give e’s to ion

lower on list


Double Replacement ReactionDouble Replacement Reaction

BaClBaCl22(aq)(aq) + + NaNa22SOSO44(aq) (aq) BaBaSOSO44(s)(s) + 2 + 2NaNaClCl(aq)(aq)

AXAX + BY + BY B BXX + + AAY Y AXAX + BY + BY B BXX + + AAY Y

BaBa+2+2 ClCl-1-1

NaNa+1 +1 SOSO44-2-2

Insoluble PrecipitateInsoluble PrecipitateFormed Formed


Predict the products:

AgNOAgNO33(aq)(aq) + MgClMgCl22(aq)(aq)

AgAg++ NONO33

--

MgMg+2 +2 ClCl--

AgAgClCl(s)(s)

Double Replacement ReactionDouble Replacement ReactionAXAX + + BYBY BBXX + + AAYY AXAX + + BYBY BBXX + + AAYY

Write correct formulas then balance as needed

22 22 + Mg(NO+ Mg(NO33))2(aq)2(aq)


Oxidation and reductionOxidation and reductionREDOXREDOX

Where reactants Where reactants exchange electronsexchange electrons - -

Examples:Examples:

•All types of All types of batteriesbatteries

alkaline, NiCad, car batteriesalkaline, NiCad, car batteries

•Rusting and corrosionRusting and corrosion

•MetabolismMetabolism

•Antioxidants (Vit C, E prevent oxidation)Antioxidants (Vit C, E prevent oxidation)


Oxidation and reductionOxidation and reductionREDOXREDOXWhere reactants Where reactants exchange electronsexchange electrons - -

LEOLEO the lion says GER GER LEOLEO the lion says GER GER

ReductionReduction = Gaining electrons

GER: GGain EElectrons RReduction

OxidationOxidation = Losing electronsLEO: LLose EElectrons

OOxidation


Oxidation and reductionOxidation and reduction

2 Na2 Na(s)(s) + ClCl2 (g2 (g) 2 Na2 NaClCl2 Na2 Na(s)(s) + ClCl2 (g2 (g) 2 Na2 NaClCl

1-1-1+1+

Assign Oxidation States:Assign Oxidation States:

00 00For simple ions,

Ox state = charge.charge.

For simple ions,

Ox state = charge.charge.

For element in natural form

Ox State = 00.

For element in natural form

Ox State = 00.




1-1-1+1+

Who’s loosing or gaining electrons?Who’s loosing or gaining electrons?

00 00

Loses Loses 1 e1 e- - = LEO= LEO

GainsGains 1 e1 e--=GER=GER

Na loses e- (LEO) Na gets oxidizedoxidizedNa loses e- (LEO) Na gets oxidizedoxidized

Cl gains e- (GER) Cl gets reducedreduced Cl gains e- (GER) Cl gets reducedreduced




1-1-1+1+


00 00

• NaNa loses e- (LEO) so NaNa gets oxidizedoxidized• Na Na causedcaused ClCl to get reducedto get reduced• NaNa is the is the Reducing agentReducing agent

• NaNa loses e- (LEO) so NaNa gets oxidizedoxidized• Na Na causedcaused ClCl to get reducedto get reduced• NaNa is the is the Reducing agentReducing agent

Loses Loses 1 e1 e- - =LEO=LEO

GainsGains 1 e1 e- - =GER=GER




1-1-1+1+


00 00

Loses Loses 1 e1 e- - =LEO=LEO

GainsGains 1 e1 e- - =GER=GER

• ClCl gains e- (GER) so ClCl gets reducedreduced • Cl Cl causedcaused NaNa to get oxidizedto get oxidized

• ClCl is the is the Oxidizing agentOxidizing agent

• ClCl gains e- (GER) so ClCl gets reducedreduced • Cl Cl causedcaused NaNa to get oxidizedto get oxidized

• ClCl is the is the Oxidizing agentOxidizing agent


1 pair =1 pair =

1 dozen =1 dozen =

1 mole =1 mole =

1 pair =1 pair =

1 dozen =1 dozen =

1 mole =1 mole =

The MoleThe Mole

1 mol eggs___

6.02 x 106.02 x 102323eggseggs

1 mol eggs___

6.02 x 106.02 x 102323eggseggs

1 mol Au_______

6.02 x 106.02 x 102323 Au atoms Au atoms

1 mol Au_______

6.02 x 106.02 x 102323 Au atoms Au atoms

_____1 mole H_____1 mole H22O_____ O_____

6.02 x 106.02 x 102323 H H22O moleculesO molecules

_____1 mole H_____1 mole H22O_____ O_____

6.02 x 106.02 x 102323 H H22O moleculesO molecules

22

1212

6.02 x 106.02 x 102323

602,000,000,000,000,000,000,000.602,000,000,000,000,000,000,000.


1 car ___1 car ___

4 wheels4 wheels

The Mole & FormulasThe Mole & Formulas

1 mol cars_

4 mol wheels4 mol wheels1 doz cars1 doz cars

4 doz wheels4 doz wheels

1 mole H1 mole H22O O

2 mol H2 mol H

1 mole H1 mole H22O O

1 mol O1 mol O


= wheels= wheels= wheels= wheels

1 car ___1 car ___

4 wheels4 wheels

The Mole & FormulasThe Mole & Formulas

1 mol cars_

4 mol wheels4 mol wheels1 doz cars1 doz cars

4 doz wheels4 doz wheels

4 doz wheels

1doz cars

5 doz cars5 doz cars

120 doz20 doz20 doz20 doz

2 mol H

1 mol H2O

5 mol H5 mol H22OO

1

10 10 10 10 = mol H= mol H= mol H= mol H


1 mole = MW in g’s 1 mole = MW in g’s The Mole & Molecular MassThe Mole & Molecular Mass

1 mol S_

32 g S32 g S

1 mol S_

32 g S32 g S

1 mole S = 32 g S1 mole S = 32 g S1 mole S = 32 g S1 mole S = 32 g S

32 g S32 g S

1 mol S

32 g S32 g S

1 mol S

1 mol C

12 g C12 g C

1 mol C

12 g C12 g C

1 mole C = 12 g C1 mole C = 12 g C1 mole C = 12 g C1 mole C = 12 g C

12 g C12 g C

1 mol C

12 g C12 g C

1 mol C


The Mole & Molecular MassThe Mole & Molecular Mass 1 mol H2O_

18.0 g H18.0 g H22OO

1 mol H2O_

18.0 g H18.0 g H22OO 1 mole H1 mole H22O has:O has:1 mole H1 mole H22O has:O has:

1.0 g H =

1 mol H

2 mol H 2 mol H

1

2.0 g H2.0 g H2.0 g H2.0 g H

16.0 g O =

1 mol O

1 mol O 1 mol O

1

16.0 g O16.0 g O16.0 g O16.0 g O

18.0 g H18.0 g H22OO

1 mol H2O

18.0 g H18.0 g H22OO

1 mol H2O

18.0 g18.0 g18.0 g18.0 g


Molecular MassMolecular MassFind the MW of Glucose; CFind the MW of Glucose; C66HH1212OO66Find the MW of Glucose; CFind the MW of Glucose; C66HH1212OO66

1.0 g H =

1 mol H

12 mol H 12 mol H

1

12.0 g H12.0 g H12.0 g H12.0 g H

16.0 g O =

1 mol O

6 mol O 6 mol O

1

96.0 g O96.0 g O96.0 g O96.0 g O

180.0 g C180.0 g C66HH1212OO66

1 mol CC66HH1212OO66

180.0 g C180.0 g C66HH1212OO66

1 mol CC66HH1212OO66

12.0 g C =

1 mol C

6 mol C 6 mol C

172.0 g C72.0 g C72.0 g C72.0 g C


1 mol H2O =

18 g H2O

Mass to Mole ConversionsMass to Mole Conversions

How many moles of water are in How many moles of water are in 36 g H36 g H22O?O?

How many moles of water are in How many moles of water are in 36 g H36 g H22O?O?

What should the What should the answeranswer look like? look like?

What is What is UniqueUnique to the problem? to the problem?

36 g H36 g H22O O

1

mol Hmol H22OO2.02.02.02.0


1 mol H2O

18 g H2O

Mass to Mole ConversionsMass to Mole Conversions

How many moles of H are in How many moles of H are in 36 g H36 g H22O?O?

How many moles of H are in How many moles of H are in 36 g H36 g H22O?O?

What should the What should the answeranswer look like? look like?


36 g H36 g H22O O

1

molmol H H4.04.04.04.0 2 mol H =

1 mol H2O


180 g Gluc =

1 mol Gluc

Mole to Mass ConversionsMole to Mass Conversions

How many g’s of Glucose (CHow many g’s of Glucose (C66HH1212OO66) )

are in 5 mol Glucose?are in 5 mol Glucose?What should the What should the answeranswer look like? look like?


5 mol Gluc5 mol Gluc

1

g Glucoseg Glucose900900900900


Moles in Chemical EquationsMoles in Chemical Equations

2 Na2 Na(s)(s) + ClCl2 (g2 (g) 2 Na2 NaClCl

2 mol Na

1 mol Cl1 mol Cl22

2 mol Na

1 mol Cl1 mol Cl22

2 mol Na

2 mol NaCl

2 mol Na

2 mol NaCl

1 mol ClCl22

2 mol NaCl2 mol NaCl

1 mol ClCl22


How many gs of ClCl2 2 are needed to are needed to

produce 2.5 mol NaCl?produce 2.5 mol NaCl?




Moles in Chemical EquationsMoles in Chemical Equations2 Na2 Na(s)(s) + ClCl2 (g2 (g) 2 Na2 NaClCl

1 mol Cl2

70.9 g Cl2

1 mol Cl2

70.9 g Cl2

1 mol ClCl22


1 mol ClCl22





produce 2.5 mol NaCl?produce 2.5 mol NaCl?• Identify any conversion factors.

•How should the answer look?

2.5 mol NaCl2.5 mol NaCl = g= g

• What is unique to the problem?

88.62588.625

= = 8989 g g

1 mol ClCl22


1 mol ClCl22


70.9 g Cl2

1 mol Cl2

70.9 g Cl2

1 mol Cl2


HH22OOHH22OO

more stablemore stablemore stablemore stable


Exothermic reactionExothermic reactionExothermic reactionExothermic reaction

--H= heat of reactionH= heat of reaction

En

erg

y

Rxn Progress

Reactants

Products

EEactact= Activation Energy= Activation Energy

(Gets hot)(Gets hot)

HH22 + O + O22HH22 + O + O22

2H2H22 + O + O222H2H22 + O + O22 2H2H22O + EnergyO + Energy2H2H22O + EnergyO + Energy


Exothermic ReactionsExothermic ReactionsE

ner

gy

Rxn Progress

2Mg + O2 2MgO + Energy

2H2 + O2 2H2O + Energy

CHCH44 + 2O + 2O22 COCO22 + 2H + 2H22O +O + 213 kcal213 kcal


more stablemore stablemore stablemore stable


Endothermic reactionEndothermic reactionEndothermic reactionEndothermic reaction

H= heat of reactionH= heat of reactionEn

erg

y

Rxn Progress

Reactants

Products

EEactact== Activation Energy Activation Energy

(Gets cold)(Gets cold)


En

erg

y

Rxn Progress

2H2(g) + O2(g) 2H2O + Energy2H2(g) + O2(g) 2H2O + Energy

Just because something has the potential to reactJust because something has the potential to react doesn’t mean it will do so immediately.doesn’t mean it will do so immediately.Just because something has the potential to reactJust because something has the potential to react doesn’t mean it will do so immediately.doesn’t mean it will do so immediately.

HH2(g)2(g) + OO2(g)2(g) may may

stay together for stay together for

lifetime without lifetime without

reacting to form reacting to form

water.water.

HH2(g)2(g) + OO2(g)2(g) may may

stay together for stay together for

lifetime without lifetime without

reacting to form reacting to form

water.water.



Oxidation: Paper burningburning Oxidation: Paper burningburning

Paper turning Paper turning yellowyellowPaper turning Paper turning yellowyellow

Oxidation: Nails rustingrustingOxidation: Nails rustingrusting


Fast:Fast:

Slow:Slow:


They have to have enough E.


For reactants to make products:For reactants to make products:

•Molecules must collidecollide

(solvents really help)(solvents really help)

•They have to be alignedaligned correctly.

(Parked cars don’t collide)(Parked cars don’t collide)



Factors that increase reaction rate:Factors that increase reaction rate:1.1. More Reactants:More Reactants:

More cars More cars More collisions More collisions

8 blocks:8 blocks:34 surfaces34 surfaces

8 blocks:8 blocks:24 surfaces24 surfaces

More surface area More surface area More collisions More collisions



Factors that increase reaction rate:Factors that increase reaction rate:2.2. Higher Temperature:Higher Temperature:

Faster cars Faster cars More collisions More collisions

More Energy More Energy More collisions More collisions



Factors that increase reaction rate:Factors that increase reaction rate:3.3. Adding a Catalyst:Adding a Catalyst:

Lower ELower Eactact More collisions More collisions

Uncatalysed reactionUncatalysed reaction


Alter the reaction mechanism Alter the reaction mechanism but not change the productsbut not change the products

Uncatalysed reactionUncatalysed reaction

Catalysed reactionCatalysed reaction

Lower activation energy

A catalyst will:A catalyst will:

EnzymesEnzymes are biological catalysts.EnzymesEnzymes are biological catalysts.

CatalystsCatalysts

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5 - 1CH110: Chapter 5 CH110 Chapter 5 Chemical Reactions Chemical Changes Chemical Equations Types...

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