1. Chapter 8 Types of Reactions

2. I. Introduction A.There are 5 basic reaction types: 1) Combination 2) Decomposition 3) Single Replacement 4) Double Replacement 5) Combustion

3. B. Three different presentations of equations are possible: 1) Molecular equation 2) ionic equation 3) net ionic equation* * Net ionic equations are only relevant for single and double replacements

4. C. A “net ionic equation” eliminates those equation members who are identical on the reactant side and product side 1) these are called “spectator ions” 2) If no ions are present, then all members are kept in the final equation

5. Ex: 2 KClO 3 ---> 2 KCl + 3 O 2 (all members are kept in final equation) [Only molecular equation is written] Ex: Zn + 2 HCl (aq) --> ZnCl 2(aq) + H 2 Zn + 2 H + + 2 Cl - --> Zn +2 + 2 Cl - + H 2 Zn + 2 H + --> Zn +2 + H 2 [ the “2 Cl - ” were eliminated because they did not change from reactants to products]

6. Ex: HCl (aq) + NaOH (aq) --> NaCl (aq) + H 2 O (aq) H + + Cl - + Na + + OH - --> Na + + Cl - + H 2 O H + + OH - --> H 2 O [ the Cl - and Na + were eliminated as they did not change ]

7. II. Combination Reactions A.ONLY ONE PRODUCT is formed B. Possible reactants can be: 1) element + element ex: 2 H 2 + O 2 --> H 2 O ex: 2 Na + Cl 2 --> 2 NaCl 2) nonmetal oxides + water --> acids ex: SO 3 + H 2 O --> H 2 SO 4 3) metal oxides + water --> bases ex: MgO + H 2 O --> Mg(OH) 2

8. A.ONLY ONE REACTANT B.Types of reactants include: 1) chlorates --> oxygen + metal chloride ex: 2 KClO 3 --> 3 O 2 + 2 KCl 2) carbonate --> carbon dioxide + metal oxide ex: CaCO 3 --> CO 2 + CaO ex: 2 NaHCO 3 --> CO 2 + Na 2 CO 3 + H 2 O III. Decomposition Reactions

9. 3) hydroxides --> water + metal oxide ex: Mg(OH) 2 --> H 2 O + MgO 4) Hydrogen peroxide --> oxygen + water ex: 2 H 2 O 2 --> O 2 + 2 H 2 O 5) Binary metal oxides --> oxygen + metal ex: 2 HgO --> O 2 + 2 Hg

10. A.Element + compound --> element + compound B.Types of single replacement: 1) metal + acid --> hydrogen + salt ex: Zn + HCl (aq) --> H 2 + ZnCl 2 (aq) Note: these metals do not produce H 2 : Cu Ag Hg Pt Au IV. Single Replacement Reactions

11. 2) Metal + salt --> metal + salt ex: Cu + 2 AgNO 3 (aq) --> 2 Ag + Cu(NO 3 ) 2 (aq) 3) Metal + water --> hydrogen + base ex: 2 Na + 2 H 2 O --> H 2 + 2 NaOH (aq) Note: DO NOT produce H 2 + Na 2 O; Think of it as: ex: 2 Na + 2 HOH --> H 2 + 2 NaOH (aq) 4) Non metal + salt --> non metal + salt F 2 + 2 NaCl --> Cl 2 + 2 NaF

12. A.Involves 2 compounds reacting --> 2 new compounds formed B.Subscripts depend on partner ions C.Solubility rules MUST be used to predict precipitated products D.Products include precipitates, water, or gases IV. Double Replacement Reactions

13. E. Examples with various products: 1) precipitated products (using solubility rules) ex: 2 NaI + Pb(NO 3 ) 2 --> 2 NaNO 3 + PbI 2 AgNO 3 + NaCl --> NaNO 3 + AgCl 2) water is formed (neutralization reactions) ex: HCl + NaOH --> NaCl + H 2 O acid + base --> salt + water

14. 3) Gases are formed… these products break down into these gases: a) NH 4 OH --> NH 3 + H 2 O b) H 2 CO 3 --> CO 2 + H 2 O c) H 2 SO 3 --> SO 2 + H 2 O Ex: NH 4 Cl + NaOH --> NaCl + NH 3 + H 2 O Na 2 CO 3 + 2 HCl --> 2 NaCl + CO 2 + H 2 O Na 2 SO 3 + HCl --> NaCl + SO 2 + H 2 O

15. A.Use oxygen as a reactant B. Every element bonds with an oxygen Ex: CH 4 + 2 O 2 --> CO 2 + 2 H 2 O [All “C x H y ” compounds produce CO 2 + H 2 O] Ex: CS 2 + 2 O 2 --> CO 2 + 2 SO 2 V. Combustion Reactions

16. VI. Advanced Equation Writing A. All equations will be given in a sentence without any chemical symbols ex: Magnesium ribbon is burned in air you write: Mg + O 2 --> B. Solids are NEVER written as ions ex: “Solid sodium carbonate is added to…” Na 2 CO 3 + ….

17. The 7 Strong acids: HCl HBr HI HNO 3 HClO 3 HClO 4 H 2 SO 4 C. Strong acids ALWAYS ionize Weak acids NEVER ionize D. Solutions always ionize… (but not weak acids) F. Phases are not required (ex: aq, s, l, g) E. Soluble products always ionize

18. Examples: 1)Aluminum metal is added to a solution of hydrochloric acid Procedure: 2 Al + 6 HCl --> 2 AlCl 3 + 3 H 2 2 Al + 6 H + + 6 Cl - --> 2 Al +3 + 6 Cl - + 3 H 2 FINAL ANS: 2 Al + 6 H + --> 2 Al +3 + 3 H 2

19. Examples: 2) Sodium oxide powder is added to water Procedure: Na 2 O + H 2 O --> 2 NaOH Na 2 O + H 2 O --> 2 Na + + 2 OH - FINAL ANS: Na 2 O + H 2 O --> 2 Na + + 2 OH -

20. Examples: 3) Solutions of barium acetate and sodium sulfate are mixed Procedure: Ba(C 2 H 3 O 2 ) 2 + Na 2 SO 4 --> BaSO 4 + 2 NaC 2 H 3 O 2 Ba +2 + 2 C 2 H 3 O 2 - + 2 Na + + SO 4 -2 --> BaSO 4 + 2 Na + + 2 C 2 H 3 O 2 - FINAL ANS: Ba +2 + SO 4 -2 --> BaSO 4

21. Examples: 3) Solid sodium hydroxide is added to a solution of acetic acid Procedure: NaOH + HC 2 H 3 O 2 --> NaC 2 H 3 O 2 + H 2 O NaOH + HC 2 H 3 O 2 --> Na + + C 2 H 3 O 2 - + H 2 O FINAL ANS: NaOH + HC 2 H 3 O 2 --> Na + + C 2 H 3 O 2 - + H 2 O