1. To return to the chapter summary click Escape or close this document. gpscience.com Image Bank Foldables Video Clips and Animations Standardized Test Practice 21 Chapter Resources Click on one of the following icons to go to that resource. Chapter Review Questions Chapter Summary

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3. To return to the chapter summary click Escape or close this document. Image Bank Click on individual thumbnail images to view larger versions. 21

4. To return to the chapter summary click Escape or close this document. Image Bank To transfer images to your own power point follow the following steps: Open the “Resource” file from the CD-ROM disc – view the file in the “normal view” or “slide sorter view” mode - go to slide #2 – from there you can click through the images and follow these instructions. Click once on the image. Copy the image Go to your own power point document Paste the image. Transfer Images 21

5. To return to the chapter summary click Escape or close this document. Image Bank Cake Batter 21

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15. To return to the chapter summary click Escape or close this document. Image Bank Table – Symbols in Chemical Equations 21

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18. To return to the chapter summary click Escape or close this document. Image Bank Endothermic Reaction 21

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20. To return to the chapter summary click Escape or close this document. Foldables Chemical Reactions Make the following Foldable to help you classify chemical reactions. 21

21. To return to the chapter summary click Escape or close this document. Foldables Fold a sheet of paper in half lengthwise. 21

22. To return to the chapter summary click Escape or close this document. Foldables Make four lines evenly spaced at even intervals down the page. 21

23. To return to the chapter summary click Escape or close this document. Foldables Cut only the top layer along the four marks to make five tabs. 21

24. To return to the chapter summary click Escape or close this document. Foldables Label the tabs as shown. 21

25. To return to the chapter summary click Escape or close this document. Foldables As you read, record examples of each type of reaction from the book, then review the chapter and list other examples mentioned in the text or from classroom discussions. Classify 21

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27. To return to the chapter summary click Escape or close this document. 21.1 Reviewing Main Ideas In a chemical reaction, one or more substances are changed to new substances. Chemical Changes The substances that react are called reactants, and the new substances formed are called products.

28. To return to the chapter summary click Escape or close this document. 21.1 Reviewing Main Ideas The law of conservation of mass states that in chemical reactions, matter is neither created nor destroyed, just rearranged. Chemical Changes Chemical equations efficiently describe what happens in chemical reactions.

29. To return to the chapter summary click Escape or close this document. 21.2 Reviewing Main Ideas Balanced chemical equations give the exact number of atoms involved in the reaction. Chemical Equations A balanced chemical equation has the same number of atoms of each element on both sides of the equation. This satisfies the law of conservation of mass. When balancing chemical equations, change only the coefficients of the formulas, never the subscripts. To change a subscript would change the compound.

30. To return to the chapter summary click Escape or close this document. 21.3 Reviewing Main Ideas In synthesis reactions, two or more substances combine to form another substance. Classifying Chemical Reactions Bleach—sodium hypochlorite (NaClO)— decomposes in two ways. In one way, it forms oxygen and another product.

31. To return to the chapter summary click Escape or close this document. 21.3 Reviewing Main Ideas Classifying Chemical Reactions In single-displacement reactions, one element replaces another in a compound. In double-displacement reactions, ions in two compounds switch places, often forming a gas or insoluble compound.

32. To return to the chapter summary click Escape or close this document. 21.4 Reviewing Main Ideas Energy in the form of light, heat, sound or electricity is released from some chemical reactions known as exergonic reactions. Chemical Reactions and Energy Reactions that absorb more energy than they release are called endergonic reactions.

33. To return to the chapter summary click Escape or close this document. 21.4 Reviewing Main Ideas Reactions may be sped up by adding catalysts and slowed down by adding inhibitors. Chemical Reactions and Energy When energy is released in the form of heat, the reaction is exothermic.

34. To return to the chapter summary click Escape or close this document. Question 1 Chapter Review Answer 21 In a chemical equation, what represents how many units of each substance are involved in a reaction? Coefficients represent how many units of each substance are involved in a reaction. Subscripts indicate the number of atoms of an element in a specific compound.

35. To return to the chapter summary click Escape or close this document. Nitrogen and hydrogen are diatomic gases, so you have to start with N 2 and H 2. The balanced equation is: N 2 + 3 H 2 → 2 NH 3 Write a balanced equation for the reaction in which nitrogen gas and hydrogen gas form ammonia, NH 3. Question 2 Chapter Review Answer 21

36. To return to the chapter summary click Escape or close this document. Question 3 Chapter Review 21 What is the coefficient of magnesium in the following reaction: A. 0 B. 2 C. 3 D. 4

37. To return to the chapter summary click Escape or close this document. Chapter Review Answer 21 The answer is B. Two units of magnesium react with oxygen; there are two units of magnesium in the product.

38. To return to the chapter summary click Escape or close this document. Question 4 Chapter Review 21 What does the term “oxidation” refer to? Oxidation describes the loss of electrons that occurs during chemical reactions, and that a substance becomes more positive as a result. Answer

39. To return to the chapter summary click Escape or close this document. Question 5 Chapter Review 21 What is an inhibitor? An inhibitor is a substance that slows down a chemical reaction. In the food industry, inhibitors are used to prevent spoilage of certain foods. Answer

40. To return to the chapter summary click Escape or close this document. Standardized Test Practice Question 1 21 What is the balanced equation for the reaction of lithium metal and water? A. Li + H 2 O → LiOH + H 2 B. 2 Li + H 2 O → 2 LiOH + H 2 C. 2 Li + 2 H 2 O → 2 LiOH + H 2 D. Li + OH → LiOH

41. To return to the chapter summary click Escape or close this document. Standardized Test Practice Answer 21 The answer is C. The formula for water is H 2 O. Lithium hydroxide and hydrogen gas are the products of this reaction.

42. To return to the chapter summary click Escape or close this document. Standardized Test Practice Question 2 21 Which of the following is a synthesis reaction? A. 2 H 2 (g) + O 2 (g) → 2 H 2 O(g) B. 2 H 2 O(l) → 2 H 2 (g) + O 2 (g) C. Cu(s) + 2 AgNO 3 (aq) → Cu(NO 3 ) 2 (aq) + 2 Ag(s) D. Ba(NO 3 ) 2 (aq) + K 2 SO 4 (aq) → BaSO 4 (s) + 2 KNO 3 (aq)

43. To return to the chapter summary click Escape or close this document. Standardized Test Practice Answer 21 The answer is A. The generalized formula for a synthesis reaction is two substances combine to form a new substance.

44. To return to the chapter summary click Escape or close this document. Standardized Test Practice Question 3 21 What is the reaction represented by the generalized formula AB → A + B? A. decomposition B. double displacement C. single displacement D. synthesis

45. To return to the chapter summary click Escape or close this document. Standardized Test Practice Answer 21 The answer is A. Decomposition reactions occur when one substance breaks down into two or more substances.

46. To return to the chapter summary click Escape or close this document. Standardized Test Practice Question 4 21 What type of reaction produces heat and light, as well as products containing the elements in the reactants? A. combustion B. decomposition C. displacement D. synthesis

47. To return to the chapter summary click Escape or close this document. Standardized Test Practice Answer 21 The answer is A. Combustion reactions may also be other types of reactions.

48. To return to the chapter summary click Escape or close this document. Standardized Test Practice Question 5 21 An endothermic reaction begins at 26º C and loses 2º C per minute. What is the temperature after 7 minutes? A. 40º C B. 33º C C. 14º C D. 12º C

49. To return to the chapter summary click Escape or close this document. Standardized Test Practice Answer 21 The answer is D. Endothermic reactions require heat; they do not give off heat.

50. To return to the chapter summary click Escape or close this document. 21 To advance to the next item or next page click on any of the following keys: mouse, space bar, enter, down or forward arrow. Click on this icon to return to the table of contents Click on this icon to return to the previous slide Click on this icon to move to the next slide Click on this icon to open the resources file. Help Click on this icon to go to the end of the presentation.

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