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  1. How to Use This Presentation • To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” • To advance through the presentation, click the right-arrow key or the space bar. • From the resources slide, click on any resource to see a presentation for that resource. • From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. • You may exit the slide show at any time by pressing the Esc key.

  2. Resources Chapter Presentation Bellringer Transparencies Sample Problems Visual Concepts Standardized Test Prep

  3. Chemical Equations and Reactions Chapter 8 Table of Contents Section 1Describing Chemical Reactions Section 2Balancing Chemical Equations Section 3Classifying Chemical Reactions Section 4Writing Net Ionic Equations

  4. Section1 Describing Chemical Reactions Chapter 8 Objectives • List evidence that suggests that a chemical reaction has occurred and evidence that proves that a chemical reaction has occurred. • Describe a chemical reaction by using a word equation and a formula equation. • Interpret notations in formula equations, such as those relating to states of matter or reaction conditions.

  5. Section1 Describing Chemical Reactions Chapter 8 Chemical Reaction • A chemical reaction is the process by which one or more substances change into one or more new substances. • Reactants are the original substances in a chemical reaction. • Products are the substances that are created in a chemical reaction.

  6. Visual Concepts Chapter 8 Chemical Reaction

  7. Section1 Describing Chemical Reactions Chapter 8 Evidence of a Chemical Reaction

  8. Section1 Describing Chemical Reactions Chapter 8 Reactions and Energy Changes • Energy can be released in a chemical reaction. • methane + oxygen  carbon dioxide + water + energy • Energy is a product. • Energy can be absorbed in a chemical reaction. • dinitrogen tetroxide +energy nitrogen dioxide • Energy is a reactant.

  9. Section1 Describing Chemical Reactions Chapter 8 Constructing a Chemical Equation • A chemical equation shows the chemical formulas and relative amounts of all reactants and products. • A word equation contains the names of the reactants and products. • Equations must be balanced.

  10. Section1 Describing Chemical Reactions Chapter 8 Writing a Word Equation or Formula Equation methane + oxygen  carbon dioxide + water ?CH4 + ?O2  ?CO2 + ?H2O

  11. Section1 Describing Chemical Reactions Chapter 8 Equations and Reaction Information

  12. Section2 Balancing Chemical Equations Chapter 8 Objectives • Write and interpret a balanced chemical equation for a reaction, and relate conservation of mass to the balanced equation.

  13. Section2 Balancing Chemical Equations Chapter 8 Reactions Conserve Mass • Mass cannot be created or destroyed by a chemical or physical change • Equations must be balanced. • ?Na + ?H2O  ?NaOH + ?H2

  14. Section2 Balancing Chemical Equations Chapter 8 Balancing Equations • The number of atoms for each element must be the same on the reactants’ side and on the products’ side. • Acoefficient multiplies the number of atoms of each element in the formula that follows. • H2O: ( ) hydrogen atoms, ( ) oxygen atom • 2H2O: ( ) hydrogen atoms, ( ) oxygen atoms

  15. Section2 Balancing Chemical Equations Chapter 8 Balancing Equations Sample Problem A Balance the equation for the reaction of iron(III) oxide with hydrogen to form iron and water.

  16. Balancing Equations • Sample Problem A Solution • Identify reactants and products. • reactants products • Fe2O3 + H2  Fe + H2O • Count atoms • Insert coefficients.

  17. Section2 Balancing Chemical Equations Chapter 8 Balancing Equations • Sample Problem A Solution • Identify reactants and products. • reactants products • Fe2O3 + H2  Fe + H2O • Count atoms 3 2 3 • Insert coefficients.

  18. Section2 Balancing Chemical Equations Chapter 8 Reactions Conserve Mass • Balanced equations show mass conservation • ?Na + ?H2O  ?NaOH + ?H2 • Na + H2O  NaOH + H2 • Never change subscripts to balance equations • Unbalanced: H2 + O2  H2O • Incorrect: H2 + O2  H2O2 • H2O  H2O2 • Correct: 2H2 + O2  2H2O

  19. Section2 Balancing Chemical Equations Chapter 8 Polyatomic Ions can be balanced as a group

  20. Section2 Balancing Chemical Equations Chapter 8 Balancing Equations Sample Problem C Aluminum reacts with arsenic acid, HAsO3, to form H2 and aluminum arsenate. Write a balanced equation for this reaction.

  21. Section2 Balancing Chemical Equations Chapter 8 Balancing Equations Sample Problem C Solution 1. Identify reactants and products. reactants products ( )Al + ( ) HAsO3  ( )H2 + ( ) Al(AsO3)3 2. Count Atoms 3. Insert coefficients

  22. Section3 Classifying Chemical Reactions Chapter 8 Bellringer • Describe the following terms. • Synthesis • Combustion • decomposition • displacement

  23. Section3 Classifying Chemical Reactions Chapter 8 Objectives • Identify combustion reactions, and write chemical equations that predict the products. • Identify synthesis reactions, and write chemical equations that predict the products. • Identify decomposition reactions, and write chemical equations that predict the products.

  24. Section3 Classifying Chemical Reactions Chapter 8 Objectives, continued • Identify displacement reactions, and use the activity series to write chemical equations that predict the products. • Identify double-displacement reactions, and write chemical equations that predict the products.

  25. Section3 Classifying Chemical Reactions Chapter 8 Combustion Reactions • A combustion reaction is a reaction of a carbon-based compound with oxygen. • Combustion of propane: • C3H8 + 5O2 3CO2 + 4H2O • Combustion of ethanol: • CH3CH2OH + 3O2  2CO2 + 3H2O

  26. Section3 Classifying Chemical Reactions Chapter 8 Synthesis Reactions • In a synthesis reaction a single compound forms from two or more reactants. • Two elements form a binary compound • C + O2 CO2 • 2C + O22CO • Two compounds form a ternary compound • CaO(s) + H2O(l)  Ca(OH)2(s) • CO2(g) + H2O(l)  H2CO3(aq)

  27. Section3 Classifying Chemical Reactions Chapter 8 Decomposition Reactions • In a decomposition reaction a single compound breaks down, often with the input of energy, into two or more elements or simpler compounds. • Decomposition of water electricity 2H2O(l) O2(g)+ 2H2(g) • A metal carbonate decomposes to form a metal oxide and carbon dioxide. heat CaCO3(s) CaO(s) + CO2(g)

  28. Section3 Classifying Chemical Reactions Chapter 8 Decomposition Reactions, continued Sample Problem D Predicting Products Predict the product(s) and write a balanced equation for the reaction of potassium with chlorine.

  29. Section3 Classifying Chemical Reactions Chapter 8 Decomposition Reactions, continued Sample Problem D Solution • Reaction is most likely a synthesis reaction, so the product will be binary • Potassium will lose one electron to become a 1+ ion. • Chlorine will gain one electron to become a 1– ion. • K + Cl2 KCl • Balance the equation. • 2K + Cl2 2KCl

  30. Section3 Classifying Chemical Reactions Chapter 8 Displacement Reactions • In adisplacement reactiona single element reacts with a compound and displaces another element from the compound. • 2Al(s) + 3CuCl2(aq)  2AlCl3(aq) + 3Cu(s) • Aluminum displaces copper.

  31. Visual Concepts Chapter 8 Single Displacement Reaction

  32. Section3 Classifying Chemical Reactions Chapter 8 Displacement Reactions, continued • The activity seriesranks the reactivity of elements

  33. Section3 Classifying Chemical Reactions Chapter 8 Displacement Reactions, continued Sample Problem E Determining Products by Using the Activity SeriesMagnesium is added to a solution of lead(II) nitrate. Will a reaction happen? If so, write the equation and balance it.

  34. Section3 Classifying Chemical Reactions Chapter 8 Displacement Reactions,continued Sample Problem E Solution • Identify the reactants. • Magnesium will attempt to displace lead from lead(II) nitrate. • Check the activity series. • Magnesium is more active than lead and displaces it. • Write the balanced equation. • Mg + Pb(NO3)2 Pb + Mg(NO3)2

  35. Section3 Classifying Chemical Reactions Chapter 8 Double-Displacement Reactions • In adouble-displacement reactiontwo compounds in aqueous solution appear to exchange ions and form two new compounds. • One of the products must be a solid precipitate, a gas, or a molecular compound, such as water. • HCl(aq) + NaOH(aq)  HOH(l) + NaCl(aq)

  36. Visual Concepts Chapter 8 Double-Displacement Reaction

  37. Chapter 8 Identifying Reactions and Predicting Products

  38. Section4 Writing Net Ionic Equations Chapter 8 Bellringer • Write a definition for the word spectator in terms of the part spectators play in a sporting event.

  39. Section4 Writing Net Ionic Equations Chapter 8 Objectives • Write total ionic equations for reactions in aqueous solutions. • Identify spectator ions and write net ionic equations for reactions in aqueous solutions.

  40. Section4 Writing Net Ionic Equations Chapter 8 Ionic Equations, continued • Ionic compounds dissolve in water • KI(aq) = K+(aq) + I–(aq) • Pb(NO3)2(aq) = Pb2+(aq) + (aq) • Reaction between KI and Pb(NO3)2 • 2KI(aq) + Pb(NO3)2(aq)  PbI2(s) + 2KNO3(aq) • Total Ionic Equation • 2K+(aq) + 2I–(aq) + Pb2+(aq) + (aq) •  PbI2(s) + 2K+(aq) + (aq)

  41. Section4 Writing Net Ionic Equations Chapter 8 Ionic Equations, continued • Spectator ions remain unchanged in the solution as aqueous ions. They do not react. • 2K+(aq) + 2I–(aq) + Pb2+(aq) + (aq) •  PbI2(s) + 2K+(aq) + (aq) • The net ionic equationis the chemical equation that shows only the net change. • 2I–(aq) + Pb2+(aq)  PbI2(s)

  42. Visual Concepts Chapter 8 Net Ionic Equation

  43. Section4 Writing Net Ionic Equations Chapter 8 Ionic Equations, continued • Net Ionic equations can be used for displacement reactions. • Zn(s) + Cu2+(aq) + (aq)  Cu(s) + Zn2+(aq) + (aq) • net ionic equation • Zn(s) + Cu2+(aq)  Cu(s) + Zn2+(aq)

  44. Section4 Writing Net Ionic Equations Chapter 8 Ionic Equations, continued • Check atoms and charge to balance net ionic equations. • (aq) + Ba2+(aq)  BaSO4(s) • Charge: (2–) + (2+) = 0 0 • Zn(s) + Cu2+(aq)  Cu(s) + Zn2+(aq) • Charge: 2+ 2+

  45. Chapter 8 Writing a Net Ionic Equation

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