The document discusses chemical equations and reactions, including: - Indications that a chemical reaction has occurred include evolution of energy (heat/light), production of a gas, and color change. - Chemical equations must represent known facts, contain correct formulas, and satisfy the law of conservation of mass. - The arrow in an equation signifies a reaction occurring. Equations can show reversible reactions with double arrows. - Types of chemical reactions include synthesis, decomposition, single-displacement, double-displacement, and combustion. - The activity series lists elements in order of their reactivity based on displacement reactions, and can predict if a reaction will occur.

1. Chemical Equations and Reactions CHAPTER 8

2. What is a chemical equation?

3. List and describe some indications of an occurrence of a chemical reaction.

4. List and describe some indications of an occurrence of a chemical reaction. Evolution of energy as heat and light Production of a gas Formation of a precipitate Color change

5. List and describe some characteristics of chemical equations.

6. List and describe some characteristics of chemical equations. The equation must represent known facts The equation must contain the correct formulas for the reactants and products The law of conservation of mass must be satisfied

7. What does the arrow,  , signify?

8. How do you read the equation with an arrow?

9. How do you balance a chemical equation?

10. What does it mean when a chemical reaction is reversible? Give an example.

11. Symbols and Explanations (s) (aq) (l) (g)

12. Symbols and Explanations   OR   or  heat

13. Reaction in a Bag Lab Overview 2 reactants CaCl 2 (calcium chloride) NaHCO 3 (sodium bicarbonate) Exothermic reactions gives off heat (feels hot) Endothermic reaction takes in heat (feels cool)

14. Reaction in a Bag Lab Overview CaCl 2 (calcium chloride) NaHCO 3 (sodium bicarbonate) AKA baking soda Universal indicator and vinegar

15. Reaction in a Bag Lab Overview Describe some indications that a chemical reaction occurred.

16. Reaction in a Bag Lab Overview Color change Gas produced (might smell the gas or see bubbles) Temperature change

17. Elements that Normally Exist as Diatomic Molecules Hydrogen Nitrogen Oxygen Fluorine Chlorine Bromine Iodine

18. Which element exists as a liquid? Which element exists as a solid at room temperature?

19. Significance of a Chemical Equation The coefficients of a chemical reaction indicates relative, not absolute, amounts of reactants and products H 2 (g) + Cl 2 (g)  2HCl(g)

20. Significance of a Chemical Equation The relative masses of the reactants and products of a chemical reaction can be determined from the reaction’s coefficients H 2 (g) + Cl 2 (g)  2HCl(g) Convert from moles to grams IOW: 1 molecule H 2 = 1 mol H 2 = 2.02 g H 2

21. Significance of a Chemical Equation The reverse reaction for a chemical equation has the same relative amounts of substances as the forward reaction Law of conservation of mass

22. Balancing Chemical Equations Identify the names of the reactants and the products, and write a word equation

23. Balancing Chemical Equations 2) Write a formula equation by substituting correct formulas for the names of the reactants and products

24. Balancing Chemical Equations 3) Balance the formula equation according to the law of conservation of mass using coefficients

25. Balancing Chemical Equations 4) CHECK! Count atoms to be sure that the equation is balanced.

26. Chemical Equation CH 4 (g) + O 2 (g)  CO 2 (g) + H 2 O(g)

27. Try this… Write the word and balanced chemical equations for the following: Hydrogen peroxide in an aqueous solution decomposes to produce oxygen and water

28. Try this…(SOLUTION) Write the word and balanced chemical equations for the following: Hydrogen peroxide in an aqueous solution decomposes to produce oxygen and water Hydrogen peroxide  oxygen + water 2H 2 O 2 (aq)  O 2 (g) + 2H 2 O(l)

29. Try this… Write the word and balanced chemical equations for the following: Solid copper metal reacts with aqueous silver nitrate to produce solid silver metal and aqueous copper nitrate

30. Try this…(SOLUTION) Write the word and balanced chemical equations for the following: Solid copper metal reacts with aqueous silver nitrate to produce solid silver metal and aqueous copper nitrate Copper + silver nitrate  silver + copper nitrate Cu(s) + 2AgNO 3 (aq)  2Ag(s) + Cu(NO 3 ) 2 (aq)

31. Try this… Write the word and balanced chemical equations for the following: Solid zinc metal reacts with aqueous copper sulfate to produce solid copper metal and aqueous zinc sulfate

32. Try this…(SOLUTION) Write the word and balanced chemical equations for the following: Solid zinc metal reacts with aqueous copper sulfate to produce solid copper metal and aqueous zinc sulfate Zinc + copper sulfate  copper + zinc sulfate Zn(s) + CuSO 4 (aq)  Cu(s) + ZnSO 4 (aq)

33. Try this… Write the word and balanced chemical equations for the following: Solid sodium oxide is added to water at room temperature and forms sodium hydroxide (dissolved in water). INCLUDE PHYSICAL STATES

34. Try this… SOLUTION Write the word and balanced chemical equations for the following: Solid sodium oxide is added to water at room temperature and forms sodium hydroxide (dissolved in water). INCLUDE PHYSICAL STATES Sodium oxide + water  sodium hydroxide Na 2 O(s) + H 2 O(l)  NaOH(aq)

35. Try this… Write the word and balanced chemical equations for the following: The reaction of zinc with aqueous hydrochloric acid produces a solution of zinc chloride and hydrogen gas.

36. Try this… SOLUTION Write the word and balanced chemical equations for the following: The reaction of zinc with aqueous hydrochloric acid produces a solution of zinc chloride and hydrogen gas. Zinc + hydrochloric acid  zinc chloride + hydrogen Zn(s) + 2HCl(aq)  ZnCl 2 (aq) + H 2 (g)

37. Try this… Balance the chemical equation Fe(s) + H 2 O(g) Fe 3 O 4 (s) + H 2 (g)

38. Try this… SOLUTION Balance the chemical equation 3 Fe(s) + 4 H 2 O(g) Fe 3 O 4 (s) + 4 H 2 (g)

39. Translate the following chemical equation into a sentence: BaCl 2 (aq) + Na 2 CrO 4 (aq)  BaCrO 4 (s) + 2NaCl(aq)

40. Translate the following chemical equation into a sentence: SOLUTION BaCl 2 (aq) + Na 2 CrO 4 (aq)  BaCrO 4 (s) + 2NaCl(aq) Aqueous solutions of barium chloride and sodium chromate react to produce a precipitate of barium chromate plus sodium chloride in aqueous solution

41. Section 2: Types of Chemical Reactions Synthesis Decomposition Single-displacement Double-displacement Combustion

42. SYNTHESIS AKA a Composition RXN 2 or more substances combine to form a new compound A + X  AX Examples: oxygen to produce oxides of an element 2Mg(s) + O 2 (g)  2MgO(s)

43. DECOMPOSITION A single compound undergoes a reaction that produces 2 or more simpler substances AX  A + X Electrolysis- decomposition of a substance by an electric current

44. DECOMPOSITION of… Binary Compounds Products: its elements Metal Carbonates Products: metal oxide and carbon dioxide gas Metal Hydroxides Products: metal oxide and water Metal Chlorates Products: metal chloride and water Acids Products: Nonmetal oxides and water

45. EXAMPLES DECOMPOSITION of… Binary Compounds 2H 2 O (l) 2H 2 (g) + O 2 (g) Metal Carbonates CaCO 3 (s) CaO(s) + CO 2 (g) Metal Hydroxides Ca(OH) 2 (s) CaO(s) + H 2 O(g) Metal Chlorates 2KClO 3 (s) 2KCl(s) + 3O 2 (g) Acids H 2 CO 3 (aq) CO 2 (g) + H 2 O(l)

46. SINGLE-DISPLACEMENT RXN AKA replacement reaction One element replaces a similar element in a compound A + BX  AX + B Y + BX  BY + X

47. SINGLE-DISPLACEMENT RXN Use your textbook (page 281) and give the products of each type of single displacement reaction and an example. The structure should be similar to how I did decomposition rxns

48. DOUBLE-DISPLACEMENT The ions of 2 compounds exchange places in an aqueous solution to form 2 new compounds AX + BY  AY + BX

49. DOUBLE-DISPLACEMENT Use your textbook (page 282-282) and give the products of each type of double-displacement reaction and an example. The structure should be similar to how I did decomposition rxns (and how you did single-displacement rxns)

50. COMBUSTION A substance combines with oxygen , releasing a large amount of energy in the form of light and heat 2H 2 (g) + O 2 (g)  2H 2 O(g)

51. Section 3: ACTIVITY SERIES OF THE ELEMENTS Activity: ability for an element to react Activity Series: a list of elements organized according to the ease with which the elements undergo certain chemical reactions

52. ACTIVITY SERIES Help you predict whether or not a given reaction will occur and what the products will be

53. Think back for a minute… From previous knowledge, which groups can you expect to be the most and least reactive? I expect everyone to know the answer!

54. Activity Series Metals: greater activity  greater loss of electrons (form positive ions) Nonmetals: greater activity  greater ease of gain of electrons (form negative ions)

55. Activity Series The order is determined by single-displacement reactions The most-active element is at the top of the series and can replace any element below through a single-displacement reaction

56. Activity Series Metals: greater activity  greater loss of electrons (form positive ions) Nonmetals: greater activity  greater ease of gain of electrons (form negative ions)

57. Activity Series Based on experimentation Information is used as a general guide for predicting reaction outcomes

58. Activity Series Draw table 3 (page 286) in your notes

59. Activity Series Example Zn(s) + H 2 O(l)  Sn(s) + O 2 (g) 

60. Activity Series Example Cd(s) + Pb(NO 3 ) 2 (aq)  Cu(s) + HCl(aq) 