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take fire. Figure 38 shows the needle

Fig. 38. shaped crystals which may be obtained by the first experiment.

26. ($ 53, Exp. 1.) With the aid of an air-pump, phosphorus may be burnt in chlorine in the following manner: Place the chalk cup, with a bit of phosphorus in it, on the bottom of the nitricoxide jar (No. 18), and cover the jar with a well-fitting glass plate which has in its centre a round hole, 4 of an inch in diameter. This hole is closed with a rubber cork, through which passes a glass tube connected with a second glass tube by a short piece of rubber tubing provided with a nipper-tap. Connect the jar with the air-pump by rubber tubing, and exhaust the air. Close the nipper-tap, and connect the jar with a gas-bag filled with chlorine. Open the nipper-taps, and let the chlorine pass into the jar, until the pressure within is nearly but not quite equal to that outside. The phosphorus will soon take fire. If the jar were filled full of chlorine, the heat of the burning phosphorus would expand the chlorine, and force out some of it into the air.

27. ($ 60.) The color of iodine vapor may be shown by heating a few grains of iodine in a flask over the lamp.

28. ($ 65, Exp. 1.) Use tubulated retort (No. 20). Fill it nearly full of water, put in a small piece of phosphorus, and let the mouth of the retort dip under water. Heat the retort until the water in it boils, and then drop in a stick of caustic potash through the tubulature. The water is boiled first in order to drive out the air from the retort, so that the hydric phosphide may not take fire inside, and thus cause an explosion.

29. ($ 123, Exp. 1.) The process is the same as in the experiment in $ 33, using air instead of oxygen.

30. ($ 123, Exp. 2.) Observe the precautions given in § 12.

31. ($ 142, Exp. 1.) The sugar and the potassic chlorate should be pulverized separately, and then mixed carefully. Put the mixture on an earthen dish, and let one drop of sulphuric acid fall upon it from the end of a long glass rod. The experiment is brilliant, even with much smaller quantities.

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QUESTIONS FOR REVIEW AND

EXAMINATION.

T The numbers refer to the sections of the book.

THE NON-METALLIC ELEMENTS. -1. Describe the experiments with muriatic acid. What products are obtained? The test for each? How may they be united again? 2. Describe the experiments with sodium and chlorine water. What are obtained? How is the oxygen tested? If hydrogen be burnt in oxygen, what is the product? What does this show? 3. Describe the experiment with ammonia. What new gas is obtained, and how is it tested? What does ammonia contain? 4. Define compounds and elements. Give examples of each. How many elements ? 5. What two classes of elements ? What are symbols? What is the symbol of gold? of iron? Explain. 6. What is affinity? What are its three characteristics ? Illustrate each. 7. What are molecules? atoms? Why so called? What is said of the atoms of an element? What of the molecules of a compound? What is this theory called? What is the atomic constitution of muriatic acid ? of water? of ammonia ? 8. What symbols do compounds have? What is indicated by these symbols? Illustrate. 9. What are atomic weights? The atomic weight of H? of O? of N? of Cl? How is the relative weight of the elements in a compound shown by the symbol? 10. Describe the preparation of O from KCIOg. What is a reaction? Express this reaction by an equation, and explain in full. 11. Describe experiments with charcoal, sulphur, and phosphorus. What product in each case? How may Fe be burnt in O? What product? What properties of O do these experiments illustrate? 12. What is ozone? Why so called?

20.

How obtained? How tested? 13. What are allotropic states ? 14. What are oxides? How named ? 15. What are acid oxides? anhydrides? acids? Illustrate. Explain the names and symbols of acids. 16. What are basic oxides ? bases ? How named? Illustrate. What are alkalies? 17. What are neutral oxides? 18. What is a salt? How named? Illustrate. 19. What are binary compounds? ternary compounds ? How is H prepared ? Express the reaction in an equation, and explain it. 21. What are the properties of H? Illustrate by experiments. 22. Describe the oxy-hydrogen blowpipe, and the experiments with it. What is the lime light? 23. The properties of H2O? What is said of its solvent power? 24. What is said of rain water? spring water? mineral waters? hard and soft water? sea water? 25. What is said of H2O in plants and animals? 26. What is water of crystallization? EMorescence? Deliquescence? 27. Give some account of the uses of H,0. 28. How is N prepared ? 29. The chief characteristic of N? 30. How is NO prepared? What experiments with it? 31. Define catalysis. 32. What is meant by the nascent state? 33. What is N2O3? How prepared? 34. What is NO,? N,O;? HNO3? 35. The properties of HNO3? How made? Illustrate by an equation. Explain the action of HNO, on metals ? 36. What is NO? How made? Its properties and uses?

37. What is H2N? When absorbed by water, what does it form? How is it prepared? 38. What is ammonium? Why is it considered a metal? 39. What is CN? How obtained? For what remarkable? What are some of its compounds? What are radicals? 40. What are the characteristics of N? Illustrate each. 41. Describe the allotropic forms of C. 42. What is CO2? Its properties? How prepared? Explain. How tested?

43. What is CO? Its preparation? Properties? 44. What are the sources of S? How is it purified? 45. Describe the allotropic forms of S. Its properties? 46. What is SO2? Properties and uses? Illustrate by experiment. 47. What is H2SO4? Ways of making it? Explain in full. 48. What is SO3? Properties? 49. What is H2S? Preparation? Properties and uses? 50. What is CS,? How made? Properties? 51. What elements belong to the O group? Why thus classed? 52. How is Cl prepared? Explain

the reaction. 53. Properties of Cl? Explain its bleaching power. 54. Describe the old and new methods of bleaching. How is bleaching powder made? For what else is it used? 55. How is muriatic acid made? Explain the reaction. 56. What are hydracids? oxyacids? 57. What is aqua regia? Why so called? Explain its action on gold. 58. Give the names and symbols of the Cl oxyacids. 59. Give the history and properties of Br. 60. Where is I found? Its properties? 61. Properties of F? How prepared ? 62. What is HF? How made? Uses? 63. What elements in the Cl group? What is said of them? 64. Give the history and the sources of P. Its properties? Uses? 65. What is said of the compounds of P? 66. What is said of As? 67. What elements in the N group? Why thus grouped ? 68. How is boracic acid obtained ? For what is B remarkable? 69. What is SiO2? What is said of Si? 70. What is said of the C group?

THE METALS. –71. What are some of the heaviest metals? some of the lightest? What is said of the melting points of the metals? 72. What are ores? veins, or lodes ? 73. What is Fe? Explain the symbol. What three forms of Fe in commerce? How is Fe made fibrous? How does it sometimes lose this texture? Explain welding. 74. Describe the blast-furnace. How is cast-iron made? How converted into wrought iron? Describe the reverberatory furnace. 75. How is steel made? Its properties ? Describe the Bessemer process. 76. What is Pb? How obtained? Properties? What is the action of H2O on Pb? What is said of lead pipes lined with tin? How are lead pipes best protected from water action? 77. What are the chief ores of Cu? Properties of Cu? 78. What are some of the alloys of Cu? Their composition? For what are they remarkable? 79. What is SnO2? Where found? How is Sn obtained from it? Properties of Sn? Uses? What is said of tin water pipes? 80. What alloys of Sn are mentioned ? 81. Chief ores of Zn? How reduced? Properties and uses of Zn? Its alloys? 82. Give the names and symbols of the iron oxides. What is FeSO4, and how is it made? Its uses ? What other salts of Fe are mentioned ? 83. The names and symbols of the lead oxides? What is PbC0g? How is it made? Explain. What is the

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