1. Chapters 3 & 4 Balancing and RX Types

2. Chapters 3 & 4 Table of Contents Copyright © Cengage Learning. All rights reserved 2 3.7Chemical Equations 3.8Balancing Chemical Equations 4.5 Precipitation Reactions 4.6Describing Reactions in Solution 4.4 Types of Chemical Reactions

3. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 3 1.To learn the signals or evidences that show a chemical reaction may have occurred 2.To learn to identify the characteristics of a chemical reaction 3.To learn the information given by a chemical equation Objectives

4. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 4

5. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 5 1.Whoosh 2.Can You Identify any Evidences of a Chemical Reaction?

6. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 6 Physical states of compounds are often given in a chemical equation.

7. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 7 Chemical reactions involve a rearrangement of the ways atoms are grouped together. A chemical equation represents a chemical reaction. –Reactants are shown to the left of an arrow. –Products are shown to the right of the arrow.

8. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 8 Let’s use all of your skills to write a reaction equation to describe the following: Solid Carbon reacts with gaseous oxygen to form gaseous carbon dioxide. Solid Mercury (II) oxide decomposes to produce elemental mercury metal and gaseous oxygen. Solid zinc is added to an aqueous solution of hydrogen chloride to produce gaseous hydrogen that bubbles out of the solution and zinc chloride that remains dissolved in the water.

9. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 9 The Law of Conservation of Mass states that mass is neither created nor destroyed during a chemical reaction. Plop, Plop, Fizz, Fizz….. A chemical reaction involves the rearrangement of atoms to form new substances. (Coins) The Law of Conservation of Mass

10. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 10 In a chemical reaction atoms are not created or destroyed. All atoms present in the reactants must be accounted for in the products. (magnets) –Same number of each type atom on both sides of arrow ___CH 4 ___O 2 ___CO 2 ___H 2 O

11. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 11 In a chemical reaction atoms are not created or destroyed. All atoms present in the reactants must be accounted for in the products. (magnets) –Same number of each type atom on both sides of arrow ___CH 4 ___O 2 ___CO 2 ___H 2 O

12. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 12

13. Section 3.7 Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 13 1.To learn the signals or evidences that show a chemical reaction may have occurred 2.To learn to identify the characteristics of a chemical reaction 3.To learn the information given by a chemical equation 4.Work Session: page 116 # 7,10 5.Video of Various Chemical Rx’s Ch 7(Silver I )Silver I Objectives Review

14. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 14 1.To learn to write a balanced equation for a chemical reaction 2.Are you ready?? Objectives

15. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 15 A representation of a chemical reaction: C 2 H 5 OH + 3O 2  2CO 2 + 3H 2 O reactantsproducts Reactants are only placed on the left side of the arrow, products are only placed on the right side of the arrow. The equation is balanced because all atoms present in the reactants are accounted for in the products. The balanced equation represents an overall ratio of reactants and products, not what actually “happens” during a reaction.

16. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 16 A chemical reaction is balanced by using a systematic approach: –Atoms (mass) are always conserved –Can only change the coefficients –Balance by trial and error starting with the most complicated molecule(s) –At the end check to be sure the equation is balanced (same numbers of all types of atoms on the reactant and product sides)

17. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 17 Example: Hydrogen gas and oxygen gas combine to form liquid water. –Write the formulas of the reactants and products to give the unbalanced chemical equation. ___ H 2 (g) + ___O 2 (g)  ___H 2 O(l)

18. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 18 A chemical reaction is balanced by using a systematic approach: (Patch’s Interpretation) –Make Sure you have the equation written correctly and leave spaces in front of each compound formula. –Use a pencil and don’t be afraid of erasing! –Make sure you are NOT violating the Law of Conservation of Mass!!

19. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 19 More Examples: ___K + ___H 2 O  ___H 2 + ___KOH ___CH 4 + ___O 2  ___ CO 2 + ___H 2 O ___C 2 H 5 OH + ___O 2  ___ CO 2 + ___H 2 O ___N 2 + ___H 2  ___ NH 3 ___O 2  ___ O 3 ___C 3 H 8 + ___O 2  ___ CO 2 + ___H 2 O ___HF + ___SiO 2  ___ SiF 4 + ___H 2 O ___NH 3 + ___O 2  ___ NO + ___H 2 O

20. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 20 Independent practice: ___NH 4 NO 2  ___N 2 + ___H 2 O ___NO  ___ N 2 O + ___NO 2 ___HNO 3  ___NO 2 + ___ H 2 O + ___O 2 –What is the sum of the coefficients for each equation?

21. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 21 Concept Check Which of the following are true concerning balanced chemical equations? There may be more than one true statement. I.The number of molecules is conserved. II.The coefficients tell you how much of each substance you have. III.Atoms are neither created nor destroyed. IV.The coefficients indicate the mass ratios of the substances used. V.The sum of the coefficients on the reactant side equals the sum of the coefficients on the product side.

22. Section 3.8 Balancing Chemical Equations Return to TOC Copyright © Cengage Learning. All rights reserved 22 1.To learn to write a balanced equation for a chemical reaction 2.Work Session: Page 120 # 83,84 Objectives Review

23. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 23 1.To learn to identify the solid that forms in a Double Replacement precipitation reaction 2.To learn to write: molecular, complete ionic, and net ionic equations. Objectives for Sections 4.5 and 4.6

24. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 24 A double displacement (replacement) reaction is a reaction in which a solid forms and separates from the solution.  When ionic compounds dissolve in water (dissociation), the resulting solution contains the separated ions.  Precipitate – the solid that forms.

25. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 25 Reactions in Which a Solid Forms What Happens When an Ionic Compound Dissolves in Water? VIDEO (Chapter 8 Dissolution of a solid in a liquid)VIDEO K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq)  Products Dissociation

26. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 26 Determine the possible products from the ions in the reactants. In our example K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq)  Products The possible ion combinations are Reactions in Which a Solid Forms How to Decide What Products Form

27. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 27 Reactions in Which a Solid Forms How to Decide What Products Form Decide which is most likely to be the yellow solid formed in the reaction. K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq)  Products The possible combinations are KNO 3 and BaCrO 4. –KNO 3 white solid –BaCrO 4 yellow solid

28. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 28 Precipitation of Silver Chloride

29. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 29 Pattern for a Double Replacement Reaction (DRR) AB + CD  AD + CB K 2 CrO 4 (aq) + Ba(NO 3 ) 2 (aq)  KNO 3 + BaCrO 4 Reaction will only occur if at least ONE of the products is INSOLUBLE. (Precipitate)

30. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 30 Soluble – solid dissolves in solution; (aq) is used in reaction. Insoluble – solid does not dissolve in solution; (s) is used in reaction. Insoluble and slightly soluble are often used interchangeably. Precipitates

31. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 31 1.Most nitrate (NO 3  ) salts are soluble. 2.Most alkali metal (group 1A) salts and NH 4 + are soluble. 3.Most Cl , Br , and I  salts are soluble (except Ag +, Pb 2+, Hg 2 2+ ). 4.Most sulfate salts are soluble (except BaSO 4, PbSO 4, Hg 2 SO 4, CaSO 4 ). 5.Most OH  are only slightly soluble (NaOH, KOH are soluble, Ba(OH) 2, Ca(OH) 2 are marginally soluble). 6.Most S 2 , CO 3 2 , CrO 4 2 , PO 4 3   salts are only slightly soluble, except for those containing the cations in Rule 2. Simple Rules for Solubility (Table 4.1 pg 144)

32. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 32 Concept Check Which of the following ions form compounds with Pb 2+ that are generally soluble in water? a)S 2– b)Cl – c)NO 3 – d)SO 4 2– e)Na +

33. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 33 Reactions in Which a Solid Forms

34. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 34 Describing Reactions in Aqueous Solutions Patch’s Interpretation: 1 - Dance Partner Swap 2 - Gangster Switch 3 - Balance Equation 4 – Predict Solubility

35. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 35 Practice Predicting Products and if Reaction Will Occur ___Pb(NO 3 ) 2 + ___ KI  ___AgNO 3 + ___KCl  ___KNO 3 + ___BaCl 2  ___Na 2 SO 4 + ___Pb(NO 3 ) 2  ___KOH + ___Fe(NO 3 ) 3  ___Ba(NO 3 ) 2 + ___NaCl  ___Na 2 S + ___Cu(NO 3 ) 2  ___NH 4 Cl + ___Pb(NO 3 ) 2 

36. Describing Reactions in Solution Section 4.6 Copyright © Cengage Learning. All rights reserved 36 Gives the overall reaction stoichiometry but not necessarily the actual forms of the reactants and products in solution. Reactants and products generally shown as compounds. Use solubility rules to determine which compounds are aqueous and which compounds are solids. AgNO 3 (aq) + NaCl(aq)  AgCl(s) + NaNO 3 (aq) Formula Equation (Molecular Equation)

37. Describing Reactions in Solution Section 4.6 Copyright © Cengage Learning. All rights reserved 37 Represents as ions all reactants and products that are strong electrolytes. Ag + (aq) + NO 3  (aq) + Na + (aq) + Cl  (aq)  AgCl(s) + Na + (aq) + NO 3  (aq) Complete Ionic Equation

38. Describing Reactions in Solution Section 4.6 Copyright © Cengage Learning. All rights reserved 38 Includes only those solution components undergoing a change.  Show only components that actually react (precipitate). Ag + (aq) + Cl  (aq)  AgCl(s) Ag + (aq) + NO 3  (aq) + Na + (aq) + Cl  (aq)  AgCl(s) + Na + (aq) + NO 3  (aq) Spectator ions are not included (ions that do not participate directly in the reaction).  Na + and NO 3  are spectator ions. (stay ions) Net Ionic Equation

39. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 39 Ba 2+ (aq) + CrO 4 2– (aq) → BaCrO 4 (s) The Reaction of K 2 CrO 4 (aq) and Ba(NO 3 ) 2 (aq)(net ionic)

40. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 40 Write the Complete and Net Ionic Equations for each ___Pb(NO 3 ) 2 + ___ KI  ___AgNO 3 + ___KCl  ___KNO 3 + ___BaCl 2  ___Na 2 SO 4 + ___Pb(NO 3 ) 2  ___KOH + ___Fe(NO 3 ) 3  ___Ba(NO 3 ) 2 + ___NaCl  ___Na 2 S + ___Cu(NO 3 ) 2  ___NH 4 Cl + ___Pb(NO 3 ) 2 

41. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 41 1.To learn about some of the factors that cause reactions to occur 2.To learn to identify the solid that forms in a Double Replacement precipitation reaction 3.To learn to write: molecular, complete ionic, and net ionic equations 1.Work Session: pg 172 #35, 37, 39, 41, 43 2.Dig Copy of Soly TableDig Copy of Soly Table Objectives Review for Sections 4.5 and 4.6

42. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 42 Objectives To learn how to identify the following types of reactions: 1.Double Replacement 2.Single Replacement 3.Acid- Base 4.Combustion 5.Synthesis 6.Decomposition vs Dissociation

43. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 43 Double Replacement Reactions AB + CD  AD + CB Dance Partner Swap __KCl + __AgNO 3  ___AgCl +___KNO 3

44. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 44 Single Replacement Reactions A + BC  AC + B One Cation cuts in on the Dance ___Zn + ___HCl  ___H 2 + ___ZnCl 2

45. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 45 Single Replacement Reactions Driving forces for a reaction: –Transfer of electrons –Formation of a Gas A + BC  B + AC Single replacement reaction

46. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 46 Acid – Base Reactions Arrhenius Acids A strong acid is one in which virtually every molecule dissociates (ionizes) in water to an H + ion and an anion.

47. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 47 A strong base is a metal hydroxide that is completely soluble in water, giving separate OH  ions and cations. Acid – Base Reactions Arrhenius Bases –Most common  NaOH, KOH

48. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 48 Acid – Base Reactions Acid + Base  Salt + Water (DHM) H __ + __OH  __ __ + H 2 O ___HCl + ___NaOH  ___NaCl + ___H 2 O ___HCl + ___KOH  ___KCl + ___H 2 O ___HNO 3 + ___KOH 

49. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 49 Combustion Reactions __C (S) + __O 2  __CO 2 + Energy

50. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 50 Combustion Reaction of Hydrocarbons C x H y + O 2  CO 2 + H 2 O + Energy Exothermic Endothermic __CH 4 + __O 2  __CO 2 + __H 2 O + Energy __C 3 H 8 + __O 2  __CO 2 + __H 2 O + Energy __C 8 H 18 + __O 2  __CO 2 + __H 2 O + Energy __C (S) + __O 2  __CO 2 + Energy __H 2 + __O 2  __H 2 O + Energy Involve oxygen and produce energy so rapidly that a flame results (Spontaneous)

51. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 51 Combustion Reactions Silly String NOS Nitrous Oxide Systems N 2 O- Injects more Oxygen into engine to allow for more fuel to be injected, making the combustion reaction faster, thereby producing more power. Also used medically as an anesthetic.

52. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 52 A synthesis reaction is one in which a compound forms from simpler materials. –A + B  AB –C(s) + O 2 (g)  CO 2 (g) + Energy –___Na + ___Cl 2  ___NaCl –___Mg + ___F 2  ___MgF 2 Synthesis (combination) Reactions

53. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 53 A decomposition reaction occurs when a compound is broken down into simpler substances. –AB  A + B –2H 2 O(l)  2H 2 (g) + O 2 (g) –___HgO  ___Hg + ___O 2 –___NaCl  ___Na + ___Cl 2 –Versus Dissociation??!! Decomposition Reactions

54. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 54 The ions separate and move around independently. VIDEOVIDEO Dissociation (Chapter 8 Dissolution of a solid in a liquid) Dissociation What Happens When an Ionic Compound Dissolves in Water?

55. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 55 Dissociation occurs when a compound is broken down into its Ionic Components. –AB  A + + B - –__K 2 CrO 4(s)  __K + (aq) +__CrO 4 -2 (aq) –__Ba(NO 3 ) 2(s)  __Ba +2 (aq) +__NO 3 -1 (aq) –__Pb(NO 3 ) 2(s)  __Pb +2 (aq) +__NO 3 -1 (aq) –__ KI (s)  __ K + (aq) +__ I - 1 (aq) Dissociation

56. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 56 Reactions of Metals with Nonmetals (Oxidation-Reduction) Reactions between metals and nonmetals involve a transfer of electrons from the metal to the nonmetal forming Ionic Compounds. –oxidation – reduction reaction

57. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 57 Reactions Between Metals (Oxidation-Reduction) Reactions between metals can involve a transfer of electrons. (Potato Clock) –Transfer of electrons = oxidation – reduction reaction

58. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 58 Practice Identifying Reaction Types ___K + ___Cl 2  ___KCl ___Fe 2 O 3 + ___Al  ___Al 2 O 3 + ___Fe __K 2 CrO 4 + __Ba(NO 3 ) 2  __KNO 3 + __BaCrO 4 ___HCl + ___KOH  ___KCl + ___H 2 O ___Mg + ___O 2  ___MgO + Energy ___PbO 2  ___Pb + ___O 2 ___Ba(NO 3 ) 2(s)  ___Ba +2 (aq) +___NO 3 -1 (aq) ___KBr + ___AgNO 3  ___AgBr +___KNO 3 ___HNO 3 +__NaOH  ___H 2 O+___NaNO 3

59. Section 4.4 Types of Chemical Reactions Return to TOC Copyright © Cengage Learning. All rights reserved 59 Objectives Review To learn how to identify the following types of reactions: 1.Double Replacement 2.Single Replacement 3.Acid- Base 4.Combustion 5.Synthesis 6.Decomposition vs Dissociation 7.Work Session: Page 120 # 81as instructed, 83-86 identify the reaction type ONLY.

60. Section 4.4 Types of Chemical Reactions Return to TOC Do you observe any signs that a reaction has or has not occurred? #2 Na 2 CO 3 CaCl 2 Cu(NO 3 ) 2 CaCl 2 + Na 2 CO 3  ______ + _______ Na 2 CO 3 + Cu(NO 3 ) 2  ______ + _______ CaCl 2 + Cu(NO 3 ) 2  ______ + _______

61. Section 4.4 Types of Chemical Reactions Return to TOC Do you observe any signs that a reaction has or has not occurred? #2 Na 2 CO 3 CaCl 2 Cu(NO 3 ) 2 CaCl 2 + Na 2 CO 3  ______ + _______ Na 2 CO 3 + Cu(NO 3 ) 2  ______ + _______ CaCl 2 + Cu(NO 3 ) 2  ______ + _______

62. Section 4.5 Precipitation Reactions Copyright © Cengage Learning. All rights reserved 62 Describing Reactions in Aqueous Solutions Three types of equations: –Molecular (formula) equation  complete formulas of all reactants and products –Complete ionic equation  all strong electrolytes are shown as ions –Net ionic equation  only those components of the solution that undergo a change Spectator ion (those that remain unchanged)  not shown in the net ionic equation