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Learn how to describe, balance, and classify chemical reactions. Understand the evidence and signs of a chemical reaction. Practice writing word and formula equations.

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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 Bellringer • For the following situations, list observations that you think indicate that a chemical reaction has taken place: • a cut apple turns brown • an egg changes when it cooks • a log burns • a car rusts

  5. 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.

  6. 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.

  7. Visual Concepts Chapter 8 Chemical Reaction

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

  9. Visual Concepts Chapter 8 Signs of a Chemical Reaction

  10. Visual Concepts Chapter 8 Precipitate

  11. Section1 Describing Chemical Reactions Chapter 8 Evidence of a Chemical Reaction • solution color changes • solution bubbles • copper is used up

  12. Section1 Describing Chemical Reactions Chapter 8 Chemical Reaction Versus Physical Change • chemical change – new substance forms with properties that differ from original substance • density • boiling point • melting point • physical change - changes of state • evaporation • condensation • melting • freezing

  13. 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.

  14. 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.

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

  16. Section1 Describing Chemical Reactions Chapter 8 Equations and Reaction Information • Physical States • NaHCO3(s) + HC2H3O2(aq)  NaC2H3O2(aq) + CO2(aq) + H2O(l) • solid liquid aqueous solutions • Reaction Conditions • 350°C, 25 000 kPa N2(g) + 3H2(g) 2NH3(g) catalyst

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

  18. Visual Concepts Chapter 8 Chemical Equation

  19. HW.SECTION REVIEW, pg.266 #(1-10)

  20. Section 8.1 Review • What is a chemical reaction? • 2. What is the only way to prove that a chemical • reaction has occurred? • 3. When water boils on the stove, does a chemical change or a physical change take place? • 4. Give four examples of evidence that suggests • that a chemical change probably is occurring.

  21. Section15.2 Review 5. When propane gas, C3H8, is burned with oxygen, the products are carbon dioxide and water. Write an unbalanced formula equation for the reaction. 6. Assume that liquid water forms in item 5. Write a formula equation for the reaction that shows the physical states of all compounds. 7. What does “Mn” above the arrow in a formula equation mean?

  22. Section 8.1 Review 8. What symbol is used in a chemical equation to indicate the phrase “reacts with”? 9. Solid silicon and solid magnesium chloride form when silicon tetrachloride gas reacts with magnesium metal. Write a word equation and an unbalanced formula equation. Include all of the appropriate notations. 10. Magnesium oxide forms from magnesium metal and oxygen gas. Write a word equation and an unbalanced formula equation. Include all of the appropriate notations

  23. Section2 Balancing Chemical Equations Chapter 8 Bellringer • Write a word equation for baking a cake. • Does the cake have the same properties as the ingredients? • Answer: • sugar + flour + eggs + vanilla + salt  cake • The properties are different.

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

  25. 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

  26. 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: 2 hydrogen atoms, 1 oxygen atom • 2H2O: 4 hydrogen atoms, 2 oxygen atoms

  27. Visual Concepts Chapter 8 Reading a Chemical Equation

  28. Visual Concepts Chapter 8 Balancing a Chemical Equation by Inspection

  29. 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.

  30. 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.

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

  32. Sample Problem A , Practice pg. 269 • Write a balanced equation for each of the following. • P4 + O2 → P2O5 • 2 ) C3H8 + O2 → CO2 + H2O

  33. Sample Problem A , Practice pg. 269 3 ) Ca2Si + Cl2 → CaCl2 + SiCl4 4 )Silicon reacts with carbon dioxide to form silicon carbide, SiC, and silicon dioxide.

  34. Sample Problem B , Practice pg. 271 • Write a balanced chemical equation for each of the following. • 1) C2H2 + O2 → CO2 + H2O • 2 5 4 2 • 2 ) Fe(OH)2 + H2O2 → Fe(OH)3 • 2 2 • FeS2 + Cl2 → FeCl3 + S2Cl2 • 2 5 2 2 • NH3+ O2 → NO + H2O • 4 5 4 6

  35. 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.

  36. 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 2 6 3 2 3. Insert coefficients

  37. Sample Problem C , Practice pg. 273 • Write a balanced equation for each of the following. • HgCl2 + AgNO3 → Hg(NO3)2 + AgCl • 2 ) Al + Hg(CH3COO)2 →Al(CH3COO)3 + Hg • 3 ) Calcium phosphate and water are produced when calcium hydroxide reacts with phosphoric acid

  38. HW. Section 8.2 Review Q(1-6)

  39. 4) Write each of the following reactions as a word equation, an unbalanced formula equation, and finally as a balanced equation. • When heated, potassium chlorate decomposes into potassium chloride and oxygen. • b) Silver sulfide forms when silver and sulfur, S8, react. • c) Sodium hydrogen carbonate breaks down to form sodium carbonate, carbon dioxide, and water vapor.

  40. Section Review pg. 274 • 5) Balance the following equations. • ZnS + O2 → ZnO + SO2 • b. Fe2O3 + CO → Fe + CO2 • c. AgNO3 + AlCl3 →AgCl + Al(NO3)3 • d. Ni(ClO3)2 → NiCl2 + O2

  41. Section Review pg. 274 • 6) Balance the following equations. • (NH4)2Cr2O7 → Cr2O3 + N2 + H2O • b. NH3 + CuO → N2 + Cu + H2O • c. Na2SiF6 + Na → Si + NaF • d. C4H10 + O2 → CO2 + H2O

  42. Section3 Classifying Chemical Reactions Chapter 8 Bellringer • Describe the following terms. • synthesis • decomposition • displacement

  43. 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.

  44. 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.

  45. 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

  46. Visual Concepts Chapter 8 Combustion Reaction

  47. 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)

  48. Visual Concepts Chapter 8 Synthesis Reactions

  49. 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)

  50. Visual Concepts Chapter 8 Decomposition Reaction

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