Chemical Reactions and Quantities

1. Chemical Reactions and Quantities Types of Reactions Oxidation-Reduction Reactions Dr Seemal Jelani Chem-100

2. Type of Reactions Chemical reactions are classified into four general types • Combination • Decomposition • Single Replacement • Double Replacement Dr Seemal Jelani Chem-100

3. 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 Dr Seemal Jelani Chem-100

4. Decomposition One substance is broken down (split) into two or more simpler substances. AB A + B 2HgO 2Hg + O2 2KClO3 2KCl + 3 O2 Dr Seemal Jelani Chem-100

5. 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 Dr Seemal Jelani Chem-100

6. 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 Dr Seemal Jelani Chem-100

7. Single Replacement One element takes the place of an element in a reacting compound. A + BC AB + C Zn + 2HCl ZnCl2 + H2 Fe + CuSO4FeSO4 + Cu Dr Seemal Jelani Chem-100

8. Double Replacement Two elements in reactants take the place of each other AB + CD AD + CB AgNO3 + NaCl AgCl+ NaNO3 ZnS + 2HCl ZnCl2 + H2S Dr Seemal Jelani Chem-100

9. 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 Dr Seemal Jelani Chem-100

10. 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 Dr Seemal Jelani Chem-100

11. 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 Dr Seemal Jelani Chem-100

12. Learning Check R3 Balance the combustion equation ___C5H12 + ___O2 ___CO2+ ___H2O Dr Seemal Jelani Chem-100

13. Solution R3 Balance the combustion equation 1 C5H12 + 8 O2 5 CO2+ 6 H2O Dr Seemal Jelani Chem-100

14. 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 Dr Seemal Jelani Chem-100

15. 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 Dr Seemal Jelani Chem-100

16. 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 Dr Seemal Jelani Chem-100

17. Gain/Loss of Hydrogen In organic and biological reactions oxidation = Loss of H reduction = Gain of H Dr Seemal Jelani Chem-100

18. 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- Dr Seemal Jelani Chem-100

19. 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- Dr Seemal Jelani Chem-100

20. 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 Dr Seemal Jelani Chem-100

21. 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 Dr Seemal Jelani Chem-100

22. SUMMARY OF REACTIONS Dr Seemal Jelani Chem-100