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24. Chemistry is the study of the composition of substances and the changes they undergo. 25. Organic, inorganic, analytical, physical, biochemistry 26. A law is a concise statement that summarizes the results of a broad variety of observations and experiments. A theory is a tested (by experiments) hypothesis. 27. Experiments are used to test hypotheses. 28. a. Alchemists devised laboratory apparatus and procedures and identified some substances. b. Boyle was a proponent of laboratory experimentation. c. Lavoisier emphasized quantitative laboratory work. 29. a. All are colorless b. It decomposes on heating. c. Densities of gases are much smaller than densities of solids. 30. Solid, metallic luster, gray color, high melting point, malleable 31. a. solid b. gas c. liquid d. liquid e. solid f. gas 32. a. 2, 3; b. 1, 2; c. 2, 3; d. 1, 2. 33. Some possible examples are; water, dry ice, gasoline, acetone (fingernail polish remover) 34. a. Iron is magnetic; salt is not. Salt will dissolve in water; iron will not. b. Water has a much lower boiling point than salt. It can be evaporated, leaving the salt. 35. a. odor, boiling point, rate of evaporation, density b. color, malleability, melting point, density c. density, solubility in water, boiling point 36. Heterogenous mixtures do not have a uniform composition. Homogenous mixtures have a uniform composition. 37. Components of a mixture are physically separable. 38. Homogenous: b, c, e, f. Heterogenous: a, d. 39. Compounds are chemically separable into elements. Elements cannot be separated into simpler substances. 40. Mixture: a, b, d, e. Compound: c. Element: f. 41. a. Cu b. O c. P d. Ag e. Na f. He 42. a. nitrogen, hydrogen, chlorine b. potassium, manganese, oxygen c. carbon, hydrogen, oxygen d. calcium, iodine 43. a. physical b. chemical c. chemical d. physical 44. a. color, odor, flammability, vapor pressure b. color, melting point, malleability, reaction with acid c. boiling point, freezing point, taste, density 45. Answers will vary. 46. The products, water and carbon dioxide, dissipated into the surrounding air. 47. 18g of water. 48. See the concept map on chapter interleaf page 2B. 49. Add sufficient water to dissolve all the sugar. Separate the charcoal and sand from the sugar water by filtration. Large pieces of charcoal could be separated on the basis of color. Small pieces of charcoal could be burned. 50. Answers will vary. 51. Chemical technology is applied to chemistry, geared to specific goals. Chemistry is a pure science, accumulating knowledge for its own sake. 52. Alchemists were unsuccessful at turning base metals into gold. They did develop lab apparatus and procedures which were used later by chemist. 53. a. mixtures b. mixtures 54. a. color b. six c. sodium chloride d. chlorine, it has the highest boiling point 55. The red substance is probably a compound because it is broken down chemically by heating. A new substance with new properties is formed. The shiny liquid is probably an element, but this is not yet proven. 56. a. homogenous mixture b. homogenous mixture c. heterogenous mixture d. homogenous mixture e. heterogenous mixture f. compound g. heterogenous mixture h. homogenous mixture 57. a. physical b. physical c. physical d. physical e. chemical 58. a. color and odor change, irreversible b. gas production c. formation of precipitate, not easily reversed d. color change, not easily reversed e. energy change, not easily reversed 59. a. 1 b. 3 c. 4 60. Revise your hypothesis, and devise new experiments to test the new hypothesis. 61. Gases, particles far apart; liquids, particles in contact; solids, particles tightly packed 62. A hypothesis is retained if it is supported by the results of experiments; otherwise, it is rejected. 63. Appearance will change during a change of state, which is a physical change. 64. melting point, boiling point, density, chemical reactivity 65. a. oxygen and calcium b. silicon, aluminum, and iron c. Oxygen makes up approximately 89% of the mass of water. The human body is approximately 80% water, and the oceans are mostly water. In addition, oxygen occurs in many of the minerals of the earth’s crust and is approximately 20% of the earth's atmosphere. d. Yes. The second most abundant elements in the earth’s crust, silicon, is not present in the human body, and the second most abundant element in the human body, carbon, is not among the abundant elements of the earth’s crust. If the elements found in the two places are different, then the compounds must be different, too. 66. a. two: mercury and sulfur. b. gas c. no d. many possibilities: by state, by color, alphabetically 67. No. For any discovery to take place, the discoverer must have the knowledge to recognize the significance of the observation or data. 68. Answers will vary. 69. applied chemistry 70. Elements are named for persons or places, or derived from Latin or Greek names. 71. The paint must be liquid enough to spread when sheared by the stroke of the paint brush, but it must be “solid” enough not to run after it is applied.