1. Chapter 8: Chemical Equations and Reactions 1.List signs of a chemical change 2.Correctly write a chemical equation 3.Balance a chemical equation

2. Indications of Chemical Reaction Temperature change Formation of a gas Formation of a precipitate (insoluble) Color change

3. Chemical Equations Represent known facts Contain correct formulas for reactants and products Satisfies law of conservation of mass Subscripts can NEVER be changed Coefficients CAN be changed

4. Word and Formula Equations Word Equation methane + oxygen  carbon dioxide + water Formula Equation CH 4 (g) + O 2 (g)  CO 2 (g) + H 2 O(g)

5. Additional Symbols → - “yields” ↔ - reversible reaction ↑ - gaseous product; also (g) ↓ - precipitate (s) – solid ( l ) – liquid (aq) – aqueous; dissolved in water

6. Meaning of a Chemical Equation 1.Coefficients represent relative amounts of reactants 2.Relative masses of reactants and products can be determined from coefficients 3.The reverse reaction has the same relative amounts of substances as forward reaction

7. Balancing Equations Balance elements one at a time Balance polyatomic ions as single units Balance atoms that appear only once on each side first Balance hydrogen and oxygen last

8. Types of Reactions 1.Give general equations for types of reactions 2.Classify reactions 3.List 3 types of synthesis and 6 decomposition reactions 4.List 4 types of single- replacement and 3 types of double- replacement reactions 5.Predict products of reactions given the reactants

9. Synthesis Reactions General Formula: A + X  AX

10. Synthesis with Oxygen With metals form metal oxides Ex – Mg(s) + O 2 (g)  MgO(s) K(s) + O 2 (g)  K 2 O(s) 2Fe(s) + O 2 (g)  2FeO(s) 4Fe(s) + 3O 2 (g)  2Fe 2 O 3 S 8 (s) + 8O 2 (g)  8SO 2 (g) C(s) + O 2 (g)  CO 2 (g)

11. Synthesis with Sulfur With metals produce metal sulfides Ex-16Rb(s) + S 8 (s)  8Rb 2 S(s) 8Ba(s) + S 8 (s)  8BaS(s)

12. Metals with Halogens Group 1: M + X 2  2MX Ex – Na(s) + Cl 2 (g)  2NaCl(s) Group 2: M + X 2  MX 2 Ex – Mg(s) + F 2 (g)  MgF 2 (s)

13. Metal Oxides with Water Group 1 & 2 form hydroxides Ex – K 2 O(s) + H 2 O(l)  2KOH(aq) CaO(s) + H 2 O(l)  Ca(OH) 2 (l)

14. Non-metal Oxide with Water Form oxyacids Ex – SO 2 (g) + H 2 O(l)  H 2 SO 3 (aq) P 2 O 5 (s) + 3H 2 O(l)  2H 3 PO 4 (aq)

15. Decomposition Reactions AX  A + X

16. Decomposition of Binary Compounds Breaks down into its elements Process called electrolysis

17. Decomposition of Metal Carbonates Form metal oxides and carbon dioxide

18. Decomposition of Metal Hydroxides Form metal oxides and water

19. Decomposition of Acids Break down into non-metal oxides and water

20. Single Replacement General Formula A + BX  AX + B

21. Metal Replaces Another Metal Aluminum is more reactive than lead

22. Replacement of Hydrogen in Water by a Metal More Active Metals Less Active Metals

23. Replacement of Hydrogen in an Acid by a Metal Metals more active than hydrogen

24. Replacement of Halogens Each halogen can replace the halogen below it on the periodic table

25. Double Replacement AX + BY  AY + BX Formation of a precipitate Formation of a gas Formation of water

26. Formation of a Precipitate An insoluble product forms

27. Formation of a Gas Insoluble gas forms Example

28. Formation of Water Water forms during reaction

29. Combustion Reaction Substance reacts with oxygen to release heat and light Products are often carbon dioxide and water

30. Neutralization Reaction HA + BOH  AB + HOH Usually these are acid-base reactions Products include salt and water

31. Types of Rxn Lab Due Friday That’s 10-31-08 if you’re wondering…

32. Activity Series 1.Explain the significance of an activity series 2.Use an activity series to predict if a reaction will take place

33. Metals vs. Nonmetals Greater activity of a metal indicates how easily it loses electrons Greater activity of a nonmetal indicates how easily it gains electrons In a single-replacement reaction, if an element with lower activity is to be replaced, the reaction will take place.