1. Chapter 10 Chemical Reactions

2. 2 Homework for Chap 10 Read p 273 – 286; 288 - 293 Applying the Concepts # 1 – 37, 39 – 42, 44 – 47, 49 - 53

3. 3 Molecular formula shows the actual number of atoms of each element in the smallest unit of a substance Empirical formula shows the simplest whole-number ratio of the atoms in a substance H2OH2O H2OH2O molecularempirical C 6 H 12 O 6 CH 2 O O3O3 O N2H4N2H4 NH 2 Chemical Formulas

4. Fig. 10.2 Several ways to express common molecules

5. 3 ways of representing the reaction of H 2 with O 2 to form H 2 O Chemical reaction ≡ process in which one or more substances is changed into one or more new substances Chemical equation ≡ use of chemical symbols to show what happens during a chemical reaction reactantsproducts

6. Fig. 10.4 The Combustion of Charcoal C + O 2 → CO 2 “Carbon reacts with oxygen to yield carbon dioxide”

7. Fig. 10.5 The meaning of subscripts and coefficients

8. Fig. 10.6 Illustration of the Law of Conservation of Mass

9. Fig. 10.8 Hydrocarbons and Carbohydrates C 8 H 18 C3H8C3H8 C 12 H 22 O 11

10. 10 Types of Chemical Reactions 1)Oxidation-Reduction (Redox) 2) Combination 3) Decomposition 4) Replacement 5) Ion Exchange

11. Oxidation-Reduction Reactions (electron transfer reactions) 2 Mg (s) + O 2 (g) 2 MgO (s) Mg is the reducing agent (supplies electrons and is oxidized) O 2 is the oxidizing agent (takes electrons and is reduced) Oxidation – an atom loses electrons Reduction – an atom gains electrons Mg 2+ O 2-

12. Fig. 10.9 Example of an oxidizing agent (“chlorine”) Others: 1) Bleach 2) Hydrogen peroxide 3) Oxygen 4) Ultraviolet light

13. 13 Types of Chemical Reactions 1)Oxidation-Reduction (Redox) 2) Combination 3) Decomposition 4) Replacement 5) Ion Exchange

14. Fig 10.10 Iron combines with oxygen to form rust (iron oxide) 4 Fe (s) + 3 O 2 (g) 2 Fe 2 O 3 (s)

15. Hydrogen combines with oxygen to form water (dihydrogen monoxide)

16. 16 Types of Chemical Reactions 1)Oxidation-Reduction (Redox) 2) Combination 3) Decomposition 4) Replacement 5) Ion Exchange

17. F IG. 10.11 D ECOMPOSITION OF M ERCURY O XIDE 2 HgO (s) → 2 Hg (l) + O 2 (g) heat

18. Decomposition of Hydrogen Peroxide 2 H 2 O 2 (l) → 2 H 2 O (l) + O 2 (g) (Demo)

19. 19 Types of Chemical Reactions 1)Oxidation-Reduction (Redox) 2) Combination 3) Decomposition 4) Replacement 5) Ion Exchange

20. Fig. 10.13 Replacement reaction between aluminum metal and the blue copper chloride solution 2 Al (s) 3 CuCl 2 (aq) → 2 AlCl 3 (aq) + 3 Cu (s) CuCl 2 Cu Al AlCl 3

21. Replacement reactions take place when Replacement reactions take place when a more active metal gives up electrons to a less active metal. How do we know if a replacement reaction How do we know if a replacement reaction will take place or not occur? Refer to the activity series for common metals Refer to the activity series for common metals Fig 10.12, p 264 Fig 10.12, p 264

22. Fig. 10.12 The activity series for common metals

23. 2 Na + 2H 2 O 2NaOH + H 2 ↑ Zn + 2HCl ZnCl 2 + H 2 ↑ Cu + HCl no reaction