Matter Properties and Changes

Transcription

1 Matter Properties and Changes Section 3.1 Properties of Matter pages b. Iron is more dense than aluminum. Problem-Solving Lab 1. Explain why the flow of a compressed gas must be controlled for practical and safe use. The flow of compressed gas must be controlled to control the amount and the rate at which gas is released. 2. Predict what would happen if the valve on a full tank of compressed gas were suddenly opened all the way or if the tank were accidentally punctured. Without the regulator device, the gas would rush out of the tank with a force powerful enough to transform the tank into a dangerous, uncontrolled projectile. Section 3.1 Assessment page Create a table that describes the three common states of matter in terms of their shape, volume, and compressibility. Volume Shape Compressibility Solid Definite Definite Incompressible Liquid Definite Takes shape of container and fills container to the extent of its own volume Gas Fills volume of container Takes shape of container Virtually incompressible Compressible 2. Describe the characteristics that identify a sample of matter as being a substance. The sample of matter must have a uniform and unchanging composition to be a substance. 3. Classify each of the following as a or chemical property. a. Iron and oxygen form rust. c. Magnesium burns brightly when ignited. chemical d. Oil and water do not mix. e. Mercury melts at 39 C. 4. Organize Create a chart that compares and chemical properties. Give two examples for each type of property. The chart should make clear that properties can be observed without changing the composition of the sample, which is not the case for chemical properties. Mass and density are examples of properties. Fermentation and rusting are examples of chemical properties. Section 3.2 Changes in Matter pages Practice Problems page Use the data in the table to answer the following questions. Aluminum and Liquid Bromine Reaction Before Reaction After Reaction Aluminum 10.3 g 0.0 g Liquid bromine g 8.5 g Compound 0.0 g How many grams of bromine reacted? How many grams of compound were formed? amount of bromine that reacted g 8.5 g 91.5 g amount of compound formed g 10.3 g 8.5 g g chemical Solutions Manual Chemistry: Matter and Change Chapter 3 35

2 6. From a laboratory process designed to separate water into hydrogen and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. How much water was originally involved in the process? mass reactants mass products mass reactants mass water electrolyzed mass products mass hydrogen mass oxygen 9. Challenge g of HCl(g) react with an unknown amount of NH 3 (g) to produce g of NH 4 Cl(s). How many grams of NH 3 (g) reacted? Is the law of conservation of mass observed in the above reaction? Justify your answer g g 51 g Yes. Mass of reactants equals mass of products. mass water electrolyzed mass hydrogen mass oxygen mass water electrolyzed 10.0 g 79.4 g 89.4 g 7. A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When the reaction was complete, the student obtained 39.7 g of sodium chloride. Calculate how many grams of chlorine gas reacted. How many grams of sodium reacted? mass reactants mass products mass sodium mass chlorine mass sodium chloride mass sodium 15.6 g mass sodium chloride 39.7 g Substituting and solving for mass chlorine yields 15.6 g mass chlorine 39.7 g mass chlorine 39.7 g 15.6 g 24.1 g used in the reaction. Because the sodium reacts with excess chlorine, all of the sodium (15.6 g) is used in the reaction. 8. A 10.0-g sample of magnesium reacts with oxygen to form 16.6 g of magnesium oxide. How many grams of oxygen reacted? mass reactants mass products mass magnesium mass oxygen mass magnesium oxide mass magnesium 10.0 g mass magnesium oxide 16.6 g 10.0 g mass oxygen 16.6 g mass oxygen 16.6 g 10.0 g 6.6 g Section 3.2 Assessment page Classify each example as a change or a chemical change. a. crushing an aluminum can b. recycling used aluminum cans to make new aluminum cans c. aluminum combining with oxygen to form aluminum oxide chemical 11. Describe the results of a change and list three examples of change. During a change, a substance is altered but its composition does not change. Examples will vary but may include changes such as melting, freezing, boiling, bending, and tearing. 12. Describe the results of a chemical change. List four indicators of chemical change. During a chemical change, the composition of a substance is altered. Possible indicators of chemical change include a change in color, odor, temperature, and the formation of a gas or solid from a liquid. 36 Chemistry: Matter and Change Chapter 3 Solutions Manual

3 13. Calculate Solve each of the following. a. In the complete reaction of g of sodium with g of chlorine, what mass of sodium chloride is formed? mass sodium chloride mass sodium mass chloride mass sodium chloride g g g b. A 12.2-g sample of X reacts with a sample of Y to form 78.9 g of XY. What is the mass of Y that reacted? mass X mass Y mass XY mass Y mass XY mass X 78.9 g 12.2 g 66.7 g 14. Evaluate A friend tells you, Because composition does not change during a change, the appearance of a substance does not change. Is your friend correct? Explain. The statement is incorrect. While the composition does not change, a change in appearance often accompanies a change. 17. Describe the separation technique that could be used to separate each of the following mixtures. a. two colorless liquids distillation b. a nondissolving solid mixed with a liquid filtration c. red and blue marbles of same size and mass manually separating the marbles by color 18. Concept Map Sketch a rough chart that summarizes the relationship between matter, elements, mixtures, compounds, pure substances, homogeneous mixtures, and heterogeneous mixtures. Chart will be similar to Figure Mixtures Matter Physical changes Pure substances Section 3.3 Mixtures of Matter pages Section 3.3 Assessment page Classify each of the following as either a heterogeneous or homogeneous mixture. a. tap water b. air homogeneous homogeneous c. raisin muffin heterogeneous 16. Compare mixtures and substances. Substances have a constant composition, mixtures do not. Each substance in a mixture retains its own properties, whereas the properties of a substance are different from those of the elements that comprise it. Heterogeneous mixtures dirt, blood, milk Homogeneous mixtures lemonade, gasoline, steel Elements oxygen, gold, iron Chemical changes Section 3.4 Elements and Compounds pages Compounds salt, baking soda, sugar Practice Problems page A 78.0-g sample of an unknown compound contains 12.4 g of hydrogen. What is the percent by mass of hydrogen in the compound? Percent by mass hydrogen mass hydrogen 100 mass compound _ Percent by mass hydrogen 12.4 g % 78.0 g Solutions Manual Chemistry: Matter and Change Chapter 3 37

4 20. If 1.0 g of hydrogen reacts completely with 19.0 g of fluorine, what is the percent by mass of hydrogen in the compound that is formed? mass compound 1.0 g 19.0 g 20.0 g percent by mass hydrogen mass hydrogen 100 mass compound _ percent by mass hydrogen 1.0 g % 20.0 g 21. If 3.5 g of X reacts with 10.5 g of Y to form the compound XY, what is the percent by mass of X in the compound? The percent by mass of Y? mass XY 3.50 g 10.5 g 14.0 g _ percent by mass X mass X 100 mass XY _ percent by mass X 3.50 g % X 14.0 g _ percent by mass Y mass Y 100 mass XY _ percent by mass Y 10.5 g % X 14.0 g 22. Two unknown compounds are tested. Compound I contains 15.0 g of hydrogen and g of oxygen. Compound II contains 2.0 g of hydrogen and 32.0 g of oxygen. Are the compounds the same? Compound I: mass percentage hydrogen 15.0 g /(15.0 g g) 11.1% Compound II: mass percentage hydrogen 2.0 g (2.0 g 32.0) 5.9% Because the mass compositions of the compounds are different, the compounds themselves must be different. 23. Challenge All you know about two unknown compounds is that they have the same percent by mass of carbon. With only this information, can you be sure the two compounds are the same? Explain. No, you cannot be sure. Having the same mass percentage of a single element does not guarantee that the composition of each compound is the same. Section 3.4 Assessment page Compare and contrast elements and compounds. Elements cannot be broken down into simpler substances by ordinary chemical means, whereas compounds can. 25. Describe the basic organizational feature of the periodic table of elements. The periodic table is organized by rows (called periods ) and columns (called groups or families ). Elements in the same group have similar chemical and properties. The patterns of similar properties repeat from period to period. 26. Explain how the law of definite proportions applies to compounds. The law of definite proportions describes the mass composition of a substance. 27. State the type of compounds that are compared in the law of multiple proportions? The law of multiple proportions relates the compositions of two compounds composed of the same elements. 28. Complete the table, and then analyze the data to determine if Compounds I and II are the same compound. If the compounds are different, use the law of multiple proportions to show the relationship between them. Analysis Data of Two Iron Compounds Compound Total Mass (g) Mass Fe (g) Mass O (g) Mass % Fe Mass % O I II Compound I mass percent Fe 69.95%; mass percent O 30.05%. Compound II mass percent Fe 77.73%; mass percent O 22.27%. The compounds are not the same. Compound I: Fe:O g/22.54 g Compound II, Fe:O g/12.47 g The relative mass ratio of Fe in compound I and compound II is 2.327: :3. 38 Chemistry: Matter and Change Chapter 3 Solutions Manual

5 29. Calculate the mass percent of hydrogen in water and the mass percent of oxygen in water. Mass % of hydrogen in water 20_ 100% 11% 100 Mass % of oxygen in water _ % 89% Graph Create a graph that illustrates the law of multiple proportions. Graph should be similar to Figure a Mass (g) Compound I Cu Cl Chapter 3 Assessment pages Section 3.1 Mastering Concepts 31. List three examples of substances. Explain why each is a substance. Answers will vary. Water, salt, and sugar are all substances. Each is a substance because it has a unique and unchanging composition. 32. Is carbon dioxide gas a pure substance? Explain. Yes. Carbon dioxide has a constant composition. 33. List at least three properties of water. Answers will vary. Water is odorless, colorless, a liquid, freezes at approximately 0 C, and boils at approximately 100 C. b Compound II 34. Identify each of the following as an extensive or intensive property. a. melting point intensive c Mass (g) Mass (g) Cu Cl Mass Ratio Comparison I II b. mass extensive c. density intensive d. length extensive 35. Properties are not affected by changes in temperature and pressure. Is this statement true or false? Explain. The statement is false. Properties are affected by changes in temperature, pressure. For example, the phase of a substance is determined by its temperature and pressure. Other specific examples will vary. Solutions Manual Chemistry: Matter and Change Chapter 3 39

6 36. List the three states of matter and give an example for each state. Differentiate between a gas and a vapor. Solid (ice), liquid (water), and gas (helium). Substances that are in the gas phase at room temperature are referred to as gases, whereas substances such as water vapor that are not gases at room temperature are vapors. Vapors of volatile solvents such as acetone and methanol escape if the solvent is left opened at room temperature. 37. Classify each as either solid, liquid, or gas at room temperature. a. milk b. air liquid gas c. copper e. silver tarnishes chemical f. mercury is a liquid at room temperature 39. A carton of milk is poured into a bowl. Describe the changes that occur in the milk s shape and volume. The volume of the milk remains unchanged. Milk, which is a liquid, conforms to the shape of its container, thus the shape of the milk changes as it is poured from the carton into the bowl. 40. Boiling Water At what temperature would 250 ml of water boil? 1000 ml? Is the boiling point an intensive or extensive property? Explain. 100 C. 100 C. Boiling point is an intensive property since it is independent of quantity or amount. solid d. helium gas e. diamond solid f. candle wax solid 38. Classify each as a property or a chemical property. a. aluminum has a silvery color b. gold has a density of 19 g/cm 3 c. sodium ignites when dropped in water chemical Mastering Problems 41. A scientist is given the task of identifying an unknown compound on the basis of its properties. The substance is a white solid at room temperature. Attempts to determine its boiling point were unsuccessful. Using Table 3.6, name the unknown compound. Physical Properties of Common Substances Substance Color State at 25 C Boiling Point ( C) Oxygen colorless gas 183 Water colorless liquid 100 Sucrose white solid decomposes Sodium chloride white solid 1413 Table 3.6 shows two compounds that are white solids. Sucrose decomposes before a boiling point is determined. Therefore, the unknown substance is sucrose. d. water boils at 100 C 40 Chemistry: Matter and Change Chapter 3 Solutions Manual

7 Section 3.2 Mastering Concepts 42. Label each set of diagrams in Figure 3.22 as or chemical change. 47. Salt Sodium and chlorine combine to form sodium chloride. List the reactants and products of this reaction. Sodium and chlorine are the reactants, while sodium chloride is the product formed. Iron oxygen 0 iron oxide. 48. Burning Candle After burning for three hours, a candle has lost half of its mass. Explain why this example does not violate the law of conservation of mass. The mass of the candle is conserved if you consider the gaseous products from the reaction. a. b. chemical 43. Classify each as a change or a chemical change. a. breaking a pencil in two b. water freezing and forming ice c. frying an egg 49. Describe the difference between a change and a chemical change. A change alters a substance without changing its composition, while a chemical change involves a change in composition. Mastering Problems 50. Ammonia Production A 28.0-g sample of nitrogen gas combines completely with 6.0 g of hydrogen gas to form ammonia. What is the mass of ammonia the formed? chemical d. burning wood chemical e. leaves turning color in the fall chemical 44. Ripening Is the process of the ripening a chemical or change? Explain. It is a chemical change. A green banana has different properties compared to a yellow banana. 45. Is a change in phase a or a chemical change? It s a change. The composition of the substance does not change. mass nitrogen mass hydrogen mass ammonia mass ammonia 28.0 g 6.0 g 34.0 g 51. A 13.0-g sample of X combines with a 34.0-g sample of Y to form the compound XY 2. What is the mass of the reactants? X and Y are the reactants. The formula of the compound formed is not important. mass reactants mass products 13.0 g 34.0 g 47.0 g 52. If g of sodium combines with an excess of chlorine gas to form g sodium chloride, what mass of chlorine gas is used in the reaction? mass sodium mass chlorine mass sodium chloride 46. List four indicators that a chemical change has probably taken place. Probable indicators of a chemical reaction include a change in color, odor, or temperature, and/or the production of a gas or a solid upon mixing. mass chlorine mass sodium chloride mass sodium mass chlorine g g g Solutions Manual Chemistry: Matter and Change Chapter 3 41

8 53. A substance breaks down into its component elements when it is heated. If 68.0 g of the substance is present before it is heated, what is the combined mass of the component elements after heating? 57. Name the separation method illustrated in Figure mass reactants mass products 68.0 g Regardless of what the compound decomposes into, mass must be conserved. 54. Copper sulfide is formed when copper and sulfur are heated together. In this reaction, 127 g of copper reacts with 41 g of sulfur. After the reaction is complete, 9 g of sulfur remains unreacted. What is the mass of copper sulfide formed? mass sulfur used in the reaction initial mass of sulfur mass remaining after reaction mass sulfur mass sulfur used in the reaction 41 g 9 g 32 g mass copper sulfide mass copper mass sulfur 127 g 32 g 159 g 55. When burning 180 grams of glucose in the presence of 192 grams of oxygen, water and carbon dioxide are produced. If 108 grams of water are produced; how many grams of CO 2 are produced? mass glucose mass oxygen mass carbon dioxide mass water 180 g 192 g 108 g mass carbon dioxide mass carbon dioxide 264 g. Section 3.3 Mastering Concepts 56. Describe the characteristics of a mixture. Mixtures are a blend of two or more substances in any proportion. Mixtures do not have a constant composition. The properties of the mixture are largely those of its component substances. distillation 58. Describe a method that could be used to separate each of the following mixtures. a. iron filings and sand A magnet can be used to draw the iron filings from the sand. b. sand and salt Add water to the mixture to dissolve the salt. Filter the mixture to remove the sand, and then boil off the water so only the salt remains. c. the components of ink Paper chromatography should be used to separate the components of the ink. If enough ink is available, distillation may also be used, but is far more complicated than chromatography. d. helium and oxygen gases Cool the gas mixture until it condenses, then distill the condensate. 59. A mixture is the chemical bonding of two or more substances in any proportion. Is this statement true or false. Explain. The statement is false because mixtures are blends of substances, not a chemical bonding of substances. 42 Chemistry: Matter and Change Chapter 3 Solutions Manual

9 60. Which of the following are the same and which are different? a. a substance and a pure substance same b. a heterogeneous mixture and a solution different c. a substance and a mixture different d. a homogeneous mixture and a solution same Section 3.4 Mastering Concepts 65. State the definition of element. An element is a substance that cannot be broken down into simpler substances by or chemical means. 66. Correct the following statements: a. An element is a combination of two or more compounds. A compound is combination of two or more elements. 61. Describe how a homogeneous mixture differs from a heterogeneous mixture. Homogeneous mixtures contain a single phase. Heterogeneous mixtures may have many phases. 62. Seawater is composed of salt, sand and water. Is seawater a heterogeneous or homogeneous mixture? Explain. Heterogeneous mixture. Composition is not uniform. 63. Iced Tea Use iced tea with and without ice cubes as examples to explain homogeneous and heterogeneous mixtures. If you allow all of the ice cubes to melt, what type of mixture remains? Iced tea with ice cubes is a heterogeneous mixture. Iced tea without ice cubes is a homogeneous mixture. When all ice cubes melt the remaining mixture is homogeneous. 64. Chromatography What is chromatography and how does it work? Chromatography is a technique used to separate components of a mixture. b. When a small amount of sugar is completely dissolved in water, a heterogeneous solution is formed. When a small amount of sugar is completely dissolved in water, a homogeneous solution is formed. 67. Name the elements contained in the following compounds. a. sodium chloride (NaCl) sodium and chlorine b. ammonia (NH 3 ) nitrogen and hydrogen c. ethanol (C 2 H 6 O) carbon, hydrogen, and oxygen d. bromine (Br 2 ) bromine 68. What was Dmitri Mendeleev s major contribution to the field of chemistry? Mendeleev developed the first widely accepted periodic table of elements. 69. Is it possible to distinguish between an element and a compound? Explain. Yes, elements can be distinguished from compounds. Compounds can be broken down into their component elements, whereas elements cannot be broken down into simpler substances. Solutions Manual Chemistry: Matter and Change Chapter 3 43

10 70. How are the properties of a compound related to those of the elements that comprise it? The properties of a compound are unique to that compound and are different from those of its component elements. 71. Which law states that a compound always contains the same elements in the same proportion by mass? The law of definite pro portions 72. a. What is the percent by mass of carbon in 44 grams of carbon dioxide, CO 2? mass carbon Percent by mass 100 mass carbon dioxide _ 12 g % 44 g b. What is the percent by mass of oxygen in 44 grams of carbon dioxide, CO 2? mass oxyegn Percent by mass 100 mass carbon dioxide _ 32 g % 44 g or (100% 27% 73% ) if you use the result from part (a) 73. Complete Table 3.7 by classifying the following compounds as: 1:1 or 2:2, 1:2 or 2:1, and 1:3 or 3:1. Ratios of Elements in Compounds Compound Simple Whole-Number Ratios of Elements NaCl 1:1 CuO 1:1 H 2 O 2:1 H 2 O 2 2:2 Mastering Problems 74. A 25.3-g sample of an unknown compound contains 0.8 g of oxygen. What is the percent by mass of oxygen in the compound? mass oxygen Mass Percentage oxygen 100 mass compound _ 0.8 g 100 3% 25.3 g 75. Magnesium combines with oxygen to form magnesium oxide. If g of magnesium reacts completely with 6.96 g of oxygen, what is the percent by mass of oxygen in magnesium oxide? Mass percentage oxygen 6.96 g/(10.57 g 6.96 g) 39.7% 76. When mercury oxide is heated, it decomposes into mercury and oxygen. If 28.4 g of mercury oxide decomposes, producing 2.0 g of oxygen, what is the percent by mass of mercury in mercury oxide? Mass Percentage mercury 28.4 g 2.0 g 28.3 g % mass mercury 100 mass mercury oxide 77. Carbon reacts with oxygen to form two different compounds. Compound I contains 4.82 g of carbon for every 6.44 g of oxygen. Compound II contains g of carbon for every 53.7 g of oxygen. What is the ratio of carbon to a fixed mass of oxygen for the two compounds? Compound mass C (g) mass O (g) mass C /mass O I g/6.44 g II g/53.7 g (mass ratio compound I /mass ratio compound II ) (0.748/0.375) 1.99 ~2 The ratio of carbon to a fixed mass of oxygen in compound I is 0.748:1, while in compound II it is 0.375:1. The ratio of carbon to oxygen in Compound I is twice that in Compound II. 78. A 100-g sample of an unknown salt contains 64 g of chlorine. What is the percent by mass of chlorine in the compound? mass chlorine Mass Percentage chlorine 100 mass compound _ 64 g % 100 g 44 Chemistry: Matter and Change Chapter 3 Solutions Manual

11 79. Which law would you use to compare CO and CO 2? Explain. Without doing any calculation, which of the two compounds CO and CO 2 has the highest percent by mass of oxygen in the compound. The law of multiple proportions. CO 2 will have the highest percent by mass of oxygen because it has more oxygen atoms for the same number of carbon atom. 80. Complete Table 3.8. Elements in Compounds Mass of Second Element Mass of Mass of Mass in the Com- Compound Oxygen % of Compound pound (g) (g) Oxygen (g) CuO H 2 O H 2 O CO CO Classify each mixture as homogeneous or heterogeneous. a. brass (an alloy of zinc and copper) homogeneous b. a salad heterogeneous c. blood heterogeneous d. powdered drink mix dissolved in water homogeneous 83. Phosphorus combines with hydrogen to form phosphine. In this reaction, g of phosphorus combines with excess hydrogen to produce g of phosphine. After the reaction, 310 g of hydrogen remains unreacted. What mass of hydrogen is used in the reaction? What was the initial mass of hydrogen before the reaction? Mass hydrogen g g 6.0 g Initial mass hydrogen 310 g 6.0 g 316 g Mixed Review 81. Which state(s) of matter are compressible? Which state(s) of matter are not compressible? Explain. Gases are the most compressible state of matter, solids the least. Liquids are virtually incompressible. Compressibility is determined by the amount of space between particles in each state. Gases have the greatest amount of space between particles, solids the least. 84. If you have 100 particles of hydrogen and 100 particles of oxygen, how many units of water can you form? Will you use all the particles of both elements? If not, what will remain? 50 units of water can be formed. No, 50 particles of oxygen will remain. Solutions Manual Chemistry: Matter and Change Chapter 3 45

12 85. Classify each substance as a pure substance, a homogeneous mixture, or a heterogeneous mixture. a. air homogeneous mixture b. aerosol 88. Ice Cream You might have noticed that while eating ice cream on a very hot day some of the ice cream begins to melt. Are the observed changes in the state of the ice cream a or chemical change? Justify your answer. Ice cream melting is a change since the chemical composition remains constant. heterogeneous mixture c. soil homogeneous or heterogeneous mixture depending on the soil sample d. water pure substance e. sediment heterogeneous mixture f. muddy water heterogeneous mixture 86. Indicate each as a homogenous mixture, a heterogeneous mixture, a compound, or an element. a. Pure drinking water compound b. Salty water homogenous mixture c. Helium element d. Seawater heterogeneous mixture e. Air homogenous mixture 87. Cooking List properties of eggs before and after they are cooked. Based on your observations, does a change or chemical change occur when eggs are cooked? Justify your answer. Eggs before cooking: liquid, white (clear) and bright yellow Eggs after cooking: solid opaque white and dull yellow 89. Pizza Is pizza a homogeneous or heterogeneous mixture? Explain. A pizza is a heterogeneous mixture because the individual parts of the pizza dough, sauce, cheese, toppings remain separate. 90. Sodium reacts chemically with chlorine to form sodium chloride. Is sodium chloride a mixture or a compound? Sodium chloride is a compound because it is a substance composed of the two elements sodium and chlorine, and it is formed by a chemical reaction. 91. Is air a solution or heterogeneous mixture? What technique can be used to separate air into its components? Air is a solution. Air can be separated into its components, oxygen, nitrogen and carbon dioxide by using gas chromatography. 92. Does the combination of the following elements yield a compound or a mixture: a. H 2 (g) O 2 (g) 0 Water compound b. N 2 (g) O 2 (g) 0 Air mixture Chemical change. 46 Chemistry: Matter and Change Chapter 3 Solutions Manual

13 Think Critically 93. Interpret Data A compound contains elements X and Y. Four samples with different masses were analyzed, and the masses of X and Y in each sample were plotted on a graph shown in Figure The samples are labeled I, II, III, and IV. Mass of X (g) Masses of Elements I IV III II Mass of Y (g) a. Which samples are from the same compound? How do you know? Samples I, III, and IV are the same compound. A straight line can be drawn through these three plotted points. The slope of the line is equivalent to ratio MassX/MassY. The fact that all three points are on the same line shows that they all have the same mass ratio of X to Y and must be the same compound. b. What is the approximate ratio of mass X to mass Y in the samples that are from the same compound? Mass ratio of X to Y for samples I, III, and IV is 3.75:1. c. What is the approximate ratio of mass X to mass Y in the sample(s) that are not from the same compound? Sample II mass ratio is 1.9:1 94. Apply Air is a mixture of many gases, primarily nitrogen, oxygen, and argon. Could distillation be used to separate air into its component gases? Explain. Yes. If the mixture of gases is cooled sufficiently, it will condense into a mixture of liquids. This mixture could then be distilled. 95. Analyze Is gas escaping from an opened soft drink an example of chemical or change? Explain. Physical change. The composition of CO 2 gas is the same inside and outside of the soft drink. 96. Apply Give examples of heterogeneous mixtures for the systems listed in Table 3.9. System Liquid-liquid Solid-liquid Solid-solid Heterogeneous Mixtures Example Water and oil Sand and water Iron filings and sugar Challenge Problem 97. A sample of a certain lead compound contains 6.46 grams of lead for each gram of oxygen. A second sample has a mass of g and contains g of oxygen. Are the two samples the same? Sample I: mass lead /mass oxygen 6.46 Sample II: mass lead /mass oxygen (68.54 g g)/28.76 g The two samples are not the same because the two mass lead /mass oxygen ratios are not the same. Cumulative Review 98. What is chemistry? (Chapter 1) Chemistry is the study of matter and the changes that it undergoes. 99. What is mass? Weight? (Chapter 1) Mass is the measure of the amount of matter an object contains. It is measured on a balance. The weight of an object is the amount of gravitational pull acting on the mass of an object. It is measured on a scale. Solutions Manual Chemistry: Matter and Change Chapter 3 47

14 100. Express the following in scientific notation. (Chapter 2) a. 34, b c d e. 75, f Perform the following operations. (Chapter 2) a Graph the data in Table What is the slope of the line? (Chapter 2) Energy released (kj) Energy Released by Carbon Mass (g) Energy Released (kj) Energy Released by Carbon b. ( ) ( ) c. ( ) ( ) Convert 65 C to kelvins. (Chapter 2) C 338 K Mass (g) Slope: 33 kj/g Writing in Chemistry 104. Synthetic Elements Select a synthetic element, and prepare a short written report on its development. Be sure to discuss recent discoveries, list major research centers that conduct this type of research, and describe the properties of the synthesized element. Student answers will vary. Students can obtain some information on the elements from the Merck Index or the CRC Handbook of Chemistry and Physics. 48 Chemistry: Matter and Change Chapter 3 Solutions Manual

15 Document-Based Questions Pigments Long before scientists understood the properties of elements and compounds, artists used chemistry to create pigments from natural materials. Table 3.11 gives some examples of such pigments used in ancient times. Data obtained from: Orna, Mary Virginia Chemistry, color, and art. Journal of Chemical Education 78 (10): 1305 Common Artists Pigments Used in Early Times Common Name Chemical Identity Comments Charcoal Egyptian blue Indigo Iron oxide red Verdigris elemental carbon (carbon black) calcium copper tetrasilicate, CaCuSi 4 O 10 indigotin, C 16 H 10 N Fe 2 O 3 dibasic acetate of copper Cu(C 2 H 3 O 2 ) 2 2Cu(OH) 2 produced by dry distillation of wood in a closed vessel crystalline compound containing some glass impurity derived from different plants of the genus indigofera in continuous use in all geographic regions and time periods other copper compounds, including carbonate, are also called verdigris a. Determine the mass percent of carbon in charcoal, indigo and verdigris. Charcoal: mass percent carbon 100% Indigo: mass percent carbon 73% Verdigris: mass percent carbon 14% b. Determine the mass percent of oxygen in iron oxide and Egyptian blue. Iron oxide: mass percent oxygen 30%, Egyptian blue: mass percent oxygen 43% 106. List an example of an element and a compound from Table Is the process of charcoal production from the dry distillation of dry wood a chemical or change? Explain. Chemical change. The composition of the dry wood changes into that of charcoal. Standardized Test Practice pages Mass Analysis of Two Chlorine-Fluorine Samples Sample Mass of Chlorine (g) Mass of Fluorine (g) % Cl % F I II ?? Multiple Choice 1. What are the values for % Cl and % F, respectively, for Sample II? a and b and c and d and d %Cl g % g g g %F % g g 2. Which statement best describes the relationship between the two samples? a. The compound in Sample I is the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of definite proportions. b. The compound in Sample I is the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of multiple proportions. Element C and compound Fe 2 O 3 Solutions Manual Chemistry: Matter and Change Chapter 3 49

16 c. The compound in Sample I is not the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of definite proportions. d. The compound in Sample I is not the same as in Sample II. Therefore, the mass ratio of Cl to F in both samples will obey the law of multiple proportions. d 3. After two elements react to completion in a closed container, the ratio of their masses in the container will be the same as before the reaction. Which law describes this principle? a. law of definite proportions b. law of multiple proportions c. law of conservation of mass d. law of conservation of energy c 4. Which is NOT a property of table sugar? a. forms solid crystals at room temperature b. appears a white crystals c. breaks down into carbon and water vapor when heated d. tastes sweet c 5. Which describes a substance that is in the solid state? a. Its particles can flow past one another. b. It can be compressed into a smaller volume. c. It takes the shape of its container. d. Its particles of matter are close together. d Use the diagram below to answer Questions 6 and 7. A B C 6. Which best describes Figure A? a. element b. mixture c. solution d. compound d 7. Which statement is false? a. Figure B is composed of two different compounds. b. Figure C is composed of two different compounds. c. Figure B represents 13 total atoms. d. Three different types of elements are represented in Figure C. b 8. Na, K, Li, and Cs all share similar chemical properties. In the periodic table of elements, they most likely belong to the same a. row. b. period. c. group. d. element. c 50 Chemistry: Matter and Change Chapter 3 Solutions Manual

17 9. Magnesium reacts explosively with oxygen to form magnesium oxide. Which is NOT true of this reaction? a. The mass of magnesium oxide produced equals the mass of magnesium consumed plus the mass of oxygen consumed. b. The reaction describes the formation of a new substance. c. The product of the reaction, magnesium oxide, is a chemical compound. d. Magnesium oxide has and chemical properties similar to both oxygen and magnesium. Extended Response Use the table below to answer Questions 13 to 15. Soluble Soluble in Density Particle Item in Water? Alcohol? (g/c m 3 ) Size (mm) Sawdust no no Mothball flakes Table salt Selected Properties of Substances in a Mixture no yes yes no d Short Answer 10. Compare and contrast the independent variable in an experiment with the dependent variable. Both the independent and the dependent variables can have different values during the course of an experiment. The independent variable has specific values that are predetermined by the researcher, while the dependent variable has values that are measured as a result of the experiment and therefore cannot be determined in advance. 11. A student reports the melting point of a gas as 295 C. Explain why his claim is unlikely to be correct. The value of 295 C is equivalent to 22 K. This answer does not make sense because 0 K is absolute zero and no temperature can be below this. 12. Place the following metric prefixes in order from the smallest value to the largest value: deci, kilo, centi, micro, mega, milli, giga, nano. nano, micro, milli, centi, deci, kilo, mega, giga 13. Is the mixture described in the table homogeneous or heterogeneous? Explain how you can tell. The mixture is heterogeneous. Based on particle size and color, the different substances can be readily distinguished. 14. Do the data describe chemical or properties? Explain your answer. These are properties because they depend only on the substance itself. Chemical properties depend on the behavior of substances as they react with other substances. 15. Propose a method to separate the three substances based on the properties described above. Use the solubility of mothballs in alcohol first: dissolve the mothballs and filter or decant the liquid. Use crystallization to remove the alcohol. Next, add water to the remaining substances: the sawdust will float since its density is less than that of water, and the salt will dissolve. Filter or decant to separate the two substances. Crystallize the salt to remove the water. Solutions Manual Chemistry: Matter and Change Chapter 3 51

18 16. Explain the difference between a chemical change and a change. Is the combustion of gasoline a chemical change or a change? Explain your answer. A change does not change the composition of the substance, whereas a chemical change is a process in which one or more substances are changed into new substances. The combustion of gasoline is a chemical change because the gasoline is changed into other substances during combustion. Use the table below to answer Questions 18 and 19. Percent by Mass of Carbon, Hydrogen, and Oxygen in Selected Compounds Compound % H % C % O Carbonic acid ( H 2 C O 3 ) Acetic acid (C H 3 COOH) Methanol (C H 3 OH) Methanal ( H 2 CO) Isopropanol ( C 3 H 8 O) SAT Subject Test: Chemistry 17. Which is a correct statement about methods for separating mixtures? a. Distillation results in the formation of solid particles of a dissolved substance. b. Filtration depends on differences in sizes of particles. c. Separations depend on the chemical properties of the substances involved. d. Chromatography depends on the different boiling points of substances. e. Sublimation can be used to separate two gases present in a mixture. b 18. You have a 125-g sample of one of these substances. You determine that it is made of 16.7 g H, 75.0 g C, and 33.0 g O. Which compound is it? a. acetic acid b. carbonic acid c. methanal d. methanol e. isopropanol e 19. In another experiment, you determine that a sample of acetic acid consists of 56.8% oxygen. What is your percent error? a. 3.50% b. 6.57% c. 1.07% d. 12.6% e. 2.06% b 52 Chemistry: Matter and Change Chapter 3 Solutions Manual