Chapter 5 Chemical Reactions and Quantities Types of Reactions Oxidation-Reduction Reactions LecturePLUS Timberlake 99

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 2NaCl SO3 + H2O H2SO4 LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 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

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 LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 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 LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 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 LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 Double Replacement Two elements in reactants take the place of each other AB + CD AD + CB AgNO3 + NaCl AgCl + NaNO3 ZnS + 2HCl ZnCl2 + H2S LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 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

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

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 LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 Learning Check R3 Balance the combustion equation ___C5H12 + ___O2 ___CO2 + ___H2O LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 Solution R3 Balance the combustion equation 1 C5H12 + 8 O2 5 CO2 + 6 H2O LecturePLUS Timberlake 99

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 LecturePLUS Timberlake 99

Requirements for Oxidization-Reduction Electrons are transferred Two processes occur Oxidation = Loss of electrons (LEO) Zn Zn2+ + 2e- Reduction = Gain of electrons (GER) Cu2+ + 2e- Cu 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 LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 Gain/Loss of Hydrogen In organic and biological reactions oxidation = Loss of H reduction = Gain of H LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 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- LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 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- LecturePLUS Timberlake 99

LecturePLUS Timberlake 99 Learning Check R4 In light-sensitive sunglasses, UV light initiates an oxidation-reduction reaction Ag+ + Cl- Ag + Cl A. Which reactant is oxidized 1) Ag+ 2) Cl- 3) Ag B. Which reactant is reduced? 1) Ag+ 2) Cl- 3) Cl LecturePLUS Timberlake 99

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