Types Of Reactions

Chapter 5 Chemical Reactions and Quantities Types of Reactions Oxidation-Reduction Reactions

LecturePLUS Timberlake 99

Type of Reactions Chemical reactions are classified into four general types Combination Decomposition Single Replacement Double Replacement LecturePLUS Timberlake 99

Combination (Synthesis) Two or more elements or simple compounds combine to form (synthesize) one product A + B AB 2Mg + O2 2MgO 2Na + Cl2 SO3 + H2O

2NaCl H2SO4

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Decomposition One substance is broken down (split) into two or more simpler substances. AB

A + B

2HgO

2Hg + O2

2KClO3

2KCl + 3 O2 LecturePLUS Timberlake 99

Learning Check R1 Classify the following reactions as 1) combination or 2) decomposition: ___A. H2 + Br2

2HBr

___B. Al2(CO3)3

Al2O3 + 3CO2

___C. 4 Al + 3C

Al4C3

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Solution R1 Classify the following reactions as 1) combination or 2) decomposition: _1_A. H2 + Br2

2HBr

_2_B. Al2(CO3)3

Al2O3 + 3CO2

_1_C. 4 Al + 3C

Al4C3

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Single Replacement One element takes the place of an element in a reacting compound. A + BC

AB + C

Zn + 2HCl

ZnCl2 + H2

Fe + CuSO4

FeSO4 + Cu

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Double Replacement Two elements in reactants take the place of each other AB + CD

AD + CB

AgNO3 + NaCl

AgCl + NaNO3

ZnS

ZnCl2 + H2S

+ 2HCl

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Learning Check R2 Classify the following reactions as 1) single replacement 2) double replacement __A. 2Al + 3H2SO4

Al2(SO4)3 + 3H2

__B. Na2SO4 + 2AgNO3

Ag2SO4 + 2NaNO3

__C. 3C + Fe2O3

2Fe + 3CO LecturePLUS Timberlake 99

Solution R2 Classify the following reactions as 1) single replacement 2) double replacement 1_A. 2Al + 3H2SO4

Al2(SO4)3 + 3H2

2_B. Na2SO4 + 2AgNO3

Ag2SO4 + 2NaNO3

1_C. 3C + Fe2O3

2Fe + 3CO LecturePLUS Timberlake 99

Combustion A reaction in which a compound (often carbon) reacts with oxygen C + O2

CO2

CH4 + 2O2

CO2 + 2H2O

C3H8 + 5O2

3CO2 + 4H2O

C6H12O6 + 6O2

6CO2 + 6H2O

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Learning Check R3 Balance the combustion equation

___C5H12 + ___O2

___CO2 + ___H2O

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Solution R3 Balance the combustion equation

1 C5H12 + 8 O2

5 CO2 + 6 H2O

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Oxidation and Reduction ♦ Reactions that involve a loss or gain of electrons ♦ Occurs in many of the 4 types of reactions and combustion ♦ Important in food metabolism, batteries, rusting of metals

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Requirements for OxidizationReduction Electrons are transferred Two processes occur Oxidation = Loss of electrons (LEO) Zn

Zn2+ + 2e-

Reduction = Gain of electrons (GER) Cu2+ + 2eCu LecturePLUS Timberlake 99

Balanced Red-Ox Equations Combine the oxidation and reduction reactions to make Loss of electrons = Gain of electrons Zn + Cu2+ + 2e-

Zn2+ + 2e- + Cu

Zn + Cu2+

Zn2+ + Cu

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Gain/Loss of Hydrogen In organic and biological reactions oxidation = Loss of H reduction = Gain of H

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Learning Check R3 Identify the following as an 1) oxidation or a reduction process: __A.

Sn

Sn4+ + 4e-

__B.

Fe3+ + 1e-

Fe2+

__C.

Cl2 + 2e-

2Cl-

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Solution R3 Identify the following as an 1) oxidation or a reduction process: 1_ A.

Sn

Sn4+ + 4e-

2_ B.

Fe3+ + 1e-

Fe2+

2_ C.

Cl2 + 2e-

2Cl-

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Learning Check R4 In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction Ag+ + ClAg + Cl A. Which reactant is oxidized 1) Ag+ 2) Cl3) Ag B. Which reactant is reduced? 1) Ag+ 2) Cl3) Cl LecturePLUS Timberlake 99

Solution R4 In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction Ag+ + ClAg + Cl A. Which reactant is oxidized 2) ClClCl + eB. Which reactant is reduced? 1) Ag+ Ag+ + eAg LecturePLUS Timberlake 99