1. Types of Chemical Reactions Honors Chemistry Mr. Rivas

2. Types of Chemical Reactions 1. Combustion Rxn 2. Synthesis (Combination) Rxn 3. Decomposition Rxn 4. Single Replacement Rxn 5. Double Replacement Rxn 6. Acid-Base Reactions 7. Redox Rxn

3. Combustion Rxn A substance reacts with O 2 to form compounds that contain oxygen atom(s) General Form: AB + O 2  AO + BO or A + O 2  AO

4. Combustion Rxn - Example The burning of charcoal is an example of a combustion reaction C(s) + O 2 (g)  CO 2 (g) Another important group of combustion reactions is the burning of hydrocarbons (gasoline is a mixture of hydrocarbons) Hydrocarbons contain only carbon and hydrogen atoms.

5. Three things are required to sustain a fire:

6. Combustion Rx - Hydrocarbons One important group of hydrocarbons are the alkanes (hydrocarbons with only single bonds) They have the general formula: C n H 2n+2 Where n is the number of carbon atoms

7. Combustion Rx - Hydrocarbons The formula of a hydrocarbon with 4 carbons (n = 4) would then be: C 4 H 2x4+2  C 4 H 10 What would be the formula of a hydrocarbon with 8 carbons? C 8 H 18

8. Combustion Rx - Hydrocarbons To name the hydrocarbons we use the following prefixes: 1Meta6Hexa 2Eta7Hepta 3Propa8Octa 4Buta9Nona 5Penta10Deca

9. Combustion Rx - Hydrocarbons CH 4 Methane  Natural Gas C 2 H 6 Ethane C 3 H 8 Propane  BBQ balloon gas C 4 H 10 Butane  Cigarette lighter C 5 H 12 Pentane Etc.

10. Combustion Rx - Hydrocarbons When hydrocarbons burn they produce: Carbon dioxide and water. The equation for the combustion of methane is: CH 4 + 2O 2  CO 2 + 2H 2 O

11. Is this equation already balanced?

12. Can you balance this combustion reaction chemical equation?

13. Combustion Rx – Single elements Elements can also combust. Some rapidly: 2Mg + O 2  2MgO Some slowly (Rusting) 4Fe + 3O 2  2Fe 2 O 3 (Catalyst) These reactions can also be classified as synthesis reactions.

14. Combustion Rxn - Exercises Write a balance equation for the following combustion reaction: 1) Li + O 2  Li 2 O 2) Ca + O 2  CaO 3) CO + O 2  CO 2 4) Combustion of propane

15. Combustion Rxn - Exercises Answers: 1) 4Li + O 2  2Li 2 O 2) 2Ca + O 2  2CaO 3) 2CO + O 2  2CO 2 4) C 3 H 8 + 5O 2  3CO 2 + 4H 2 O

16. Combustion Rxn - Exercises Answer questions Worksheet 9-2: Combustion Reactions The fire acts as the activation energy to initiate the combustion reaction

17. Synthesis Rxn In this reactions, two or more substances are combined together to form a single more complex compound. General form: A + B = AB

18. Synthesis Rxn - Example The reaction between chlorine gas and sodium: 2Na(s) + Cl 2 (g)  2NaCl(s) Many combustion reactions can also be classified as synthesis reactions: 2H 2 (g) + O 2 (g)  2H 2 O(g) (This is an explosive reaction)

19. Synthesis Rxn - Example The formation of acid rain results from synthesis reactions in the atmosphere: 2S(s) + 3O 2  2SO 3 (g) SO 3 + H 2 O  H 2 SO 4 (sulfuric acid) This synthesis reaction started the “Green Revolution” N 2 (g) + 3H 2 (g)  2NH 3 (g) (ammonia)

20. Synthesis Rxn - Exercises Write a balance equation for the following synthesis reactions: 1) K + I 2  KI 2) Sr + O 2  SrO 3) Na + S  Na 2 S 4) H 2 + O 2  H 2 O

21. Synthesis Rxn - Exercises ANSWERS: 1) 2K + I 2  2KI 2) 2Sr + O 2  2SrO 3) 2Na + S  Na 2 S 4) 2H 2 + O 2  2H 2 O

22. Decomposition Rxn A single compound produces two or more substances. General Form: AB  A + B

23. Decomposition Rxn - Examples When heated, carbonates decompose to form an oxide and carbon dioxide CaCO 3 (s)  CaO(s) + CO 2 (g) limestone quicklime CuCO 3 (s)  CuO(s) + CO 2 (g)

24. Decomposition Rxn - Examples Hydrogen peroxide slowly decomposes into water and oxygen (light speeds up the decomposition) 2H 2 O 2 (l)  2H 2 O(l) + O 2 (g) When heated, sucrose (sugar) decomposes into carbon and water C 12 H 22 O 11 (s)  12C(s) + 11H 2 O(g)

27. Synthesis & Decomposition Rxn - Exercises Answer questions Worksheet 9-2: Part B: Synthesis & Decomposition Reactions

28. Single Replacement Rxn A free element replaces a less active element in a compound. General Form: A + BC  AC + B (If A is more active than B)

30. Single Replacement Rxn - Examples Hydrogen in hydrochloric acid is replaced by Zn, a more active element. Zn(S) + HCl(aq)  ZnCl 2 (aq) + H 2 (g) Bromine in sodium bromide is replaced by Cl, a more active element. Cl 2 (g) + NaBr(aq)  NaCl(aq) + Br l Copper in copper sulfate is replaced by Mg, a more active element. Mg(s) + CuSO 4 (aq)  MgSO 4 (aq) + Cu(S)

31. The Activity Series of Metals LiMost Active K Ba Sr Ca Na Mg Al Mn Zn Fe Cd Co Ni Sn Pb H Cu Ag Hg Au Least Active

32. Activity Series of the Halogens Fluorine Most active Chlorine Bromine Iodine Least active

33. Single Replacement Rxn - Exercises Complete the following reaction. Enter NR if no reaction is predicted. 1) Cu + AgNO 3  2) Fe + CuSO 4  3) Mg + CaSO 4  4) Br 2 + KI 

34. Single Replacement Rxn - Answers 1) Cu + 2AgNO 3  Cu(NO 3 ) 2 + 2Ag 2) Fe + CuSO 4  FeSO4 + Cu 3) Mg + CaSO 4  NR 4) Br 2 + 2KI  2KBr + I 2

35. Single Replacement Rxn - Exercises Answer questions Worksheet 9-2: Part C: Single Replacement Reactions

36. Double Replacement Rxn The positive ion of one compound combines with the negative ion of the other compound and vice versa. General Form: AB + CD  CB + AD The solubility rules determine if a double replacement reaction will take place.

37. Double Replacement Rxn - Example The silver ion of silver nitrate forms an insoluble compound when it combines with the chloride ion of sodium chloride AgNO 3(aq) + NaCl (aq)  NaNO 3(aq) + AgCl (s) The lead(II) ion of lead(II) nitrate forms and insoluble precipitate with the iodide ion of potassium iodide. Pb(NO 3 ) 2 + 2KI  PbI(s) + 2KNO 3

38. Solubility Rules NO 3 – All nitrates are soluble Cl – All chlorides are soluble except: AgCl, Hg 2 Cl 2, PbCl 2, and CuCl SO 4 2– All sulfates are soluble except: BaSO 4, PbSO 4, SrSO 4, CaSO 4, and Ag 2 SO 4 CO 3 2– All carbonates are insoluble except: NH 4 + and those alkaline metals OH – All hydroxides are insoluble except: Alkaline metals, Ba(OH) 2, Sr(OH) 2, Ca(OH) 2 S 2– All sulfides are insoluble except: Alkali, alkaline earth metals, and NH 4 +

39. Double Replacement Rxn - Exercises Complete the following reaction indicate NR if no reaction takes place: 1) Pb(NO 3 ) 2 + K 2 SO 4  2) SrBr 2 + CuSO 4  3) MgCl 2 + NH 4 NO 3  4) CaF 2 + Li 2 CO 3  5) BeI 2 + Li 3 PO 4 

40. Double Replacement Rxn - Answers Complete the following reaction indicate NR if no reaction takes place: 1) Pb(NO 3 ) 2 + K 2 SO 4  PbSO 4 + 2KNO 3 2) SrBr 2 + CuSO 4  SrSO 4 + CuBr 2 3) MgCl 2 + NH 4 NO 3  NR 4) CaF 2 + Li 2 CO 3  CaCO 3 + 2LiF 5) 3BeI 2 + 2K 3 PO 4  Be 3 (PO 4 ) 2 + 6KI

41. Double Replacement Rxn - Exercises Answer questions Worksheet 9-2: Part C: Single Replacement Reactions and Part D: Double Replacement Reactions

42. Acid-Base Rxn According to the Brønsted-Lowry theory: 1. A base is any compound which can accept a proton. 2. An acid is any compound which can donate a proton. In an acid-base reaction, an acid and a base will react to form a salt and water.

43. Acid-Base Rxn – Example Hydrochloric acid (a proton donor) reacts with sodium hydroxide (a proton acceptor) to form sodium chloride (a salt) and water HCl + NaOH  NaCl + H 2 O acid base salt water

44. Redox Reaction A REDuction-OXidation reaction is one in which an element is oxidized and another one reduced. Oxidation is the loss of electrons while Reduction is the gain of electrons. Many of the reactions that we have covered are redox reactions.

45. Remember… OIL RIG

46. Redox Reaction - Example The reaction of Magnesium and chlorine is an example of redox reaction: loses 2 electrons Mg + Cl 2  MgCl 2 gains 2 electrons

47. Predicting Chemical Reactions Several factors such as temperature, pressure, physical state, acidity, etc, influence a chemical reaction. The only way to determine the results of a chemical reaction is by experimentation in the lab. Nevertheless, based on our classification of the types of reactions, we can make an educated guess.

48. Predicting chemical reactions Predict the results of the following reactions: 1) K + I 2  2) C 12 H 26 + O 2  3) Li + Pb(NO 3 ) 2  4) MgCO 3  5) CuSO 4 + NaOH  6) LiOH + HCl 

49. Predicting chemical reactions Predict the results of the following reactions: 1) 2K + I 2  2KI 2) 2C 12 H 26 + 37O 2  24CO 2 + 26H 2 O 3) 2Li + Pb(NO 3 ) 2  2LiNO 3 + Pb 4) MgCO 3  MgO + CO 2 5) CuSO 4 + 2NaOH  Na 2 SO 4 + Cu(OH) 2 6) LiOH + HCl  LiCl + H 2 O

50. Predicting chemical reactions Answer questions Worksheet 9-2: Part E: Potpourri of reactions

51. I want more… Chemistry!!!