Complete Text (Part 20)

Carton monoxide, or carbonous oxide, is CO— a colorless, odorless, tasteless gas which burns with a blue flame, forming C02. The CO is poisonous when inhaled. When steam is blown through incandescent coal or coke, the water (steam) is decomposed and the products are H and CO, which together constitute the gaseous mixture called water gas. Carbon dioxide, C02, is present in the air because animals exhale it. C02 is also produced in the decay of certain organic substances and by combustion. The C02 is com- monly called "carbonic acid gas," because when dissolved in water it forms a solution of carbonic acid, H2C03. Carbonic acid water is a refreshing and not unwholesome drink; but- when inhaled the gas C02 is poisonous, and even a small pro- portion of it renders air unfit to be breathed. Effective ventilation is necessary to remove the air contaminated with the C02 injected into it by respiration. Men and animals inhale air and exhale carbon dioxide. Plants decompose the carbon dioxide, appropriating the carbon and restoring the oxygen to the air. Cyanogen, (CN)2, is a colorless gas of irritating odor and very poisonous. HCN is the fearfully poisonous hydrogen cyanide, commonly called "hydrocyanic acid," or "prussic acid." SULPHUR, PHOSPHORUS, ARSENIC, ANTIMONY, ETC. 203 319. Silicon is, next to oxygen, the most abundant of all elements. Silica, Si02, and silicates of several kinds, con- stitute a large proportion of the rock, sand and clay forma- tions of the earth's surface. Quartz, flint, sand and agate are different forms of silicon dioxide or silica. Brick, earthenware, porcelain and glass are mixtures of silicon compounds. The chief constituents of glass are the silicates of potassium, sodium, calcium and lead. The pure silicates of potassium and sodium are water-soluble, but mixtures of them with the silicates of calcium and lead are not only insoluble in water but even resist the action of strong acids and alkalies to a remarkable degree. 320. Boron is an element that occurs chiefly in the com- pound called lorax, which is sodium tetraborate, Na2B407. Boric acid is H3B03, or, rather, (HO)3B. Boric acid is a remarkable antiseptic and hence used in large quantities as a preservative of meats and other perish- able organic substances and also as a harmless and yet effective constituent of antiseptic lotions, dressings and powders. Test Questions 1. Name the halogens. 2. What is the correct scientific name for hydrobromic acid ? 3. What is the maximum number of chlorine atoms that can be contained in a chloride ? 4. What is the maximum number of atoms of the positive element in any true iodide ? 5. How can tri-iodide of chlorine be made ? 6. What is the most common fluorine compound in nature ? 7. What is the most abundant chloride ? 8. How is chlorine produced ? 9. How is the great power of chlorine as a disinfectant explained ? 204 A CORRESPONDENCE COURSE IN PHARMACY 10. What is formed when iron is dissolved in a solution of hydrogen chloride ? Write the equation representing the chemical reaction. 1 1 . What is the algebraic combining number of the nitrogen in nitrosyl chloride ? 12. Write the formulas for mercurous chloride and mer- curic chloride ; for ferrous chloride and ferric chloride. 13. What is the action of chlorine on water ? 14. Why is chlorine recognized as a powerful oxidizing agent ? 15. Write the formula for ammonium bromide. 16. How is bromine liberated from a bromide ? 17. Describe bromine. 18. How does it differ from chlorine and iodine ? 19. What are the sources of iodine? 20. What is the chemical action of bromine on potassium iodide ? 21. What is the percentage of bromine in a 10 per cent solution of hydrogen bromide ? 22. What is the percentage of bromine in potassium bromide ? 23. Which contains the greater amount of iodine, a syrup containing 10 per cent of hydrogen iodide or the compound known as potassium iodide ? 24. Which of the two compounds, potassium chloride and potassium chlorate, is best able to resist decomposition when exposed to strong heat ? 25. Describe S02 and state how it is produced. 26. What is the difference between a carbonate and a thio-carbonate ? 27. What is the difference between positive sulphur and negative sulphur ? 28. What is the difference between sulphuric sulphur and hyposulphurous sulphur ? SULPHUR, PHOSPHORUS, ARSENIC, ANTIMONY, ETC. 205 29. What is formed when S03 is added to water ? 30. Write the chemical reaction occurring when S02 is dissolved in water. 31. Name the several possible products formed from S03 and water. 32. Can you name any compound containing both positive sulphur and negative sulphur ? 33. Describe phosphorus. 34. What are the differences between the two allotropic modifications of phosphorus ? 35. What is the most common source of phosphorus ? 36. How many bonds has the phosphorus atom in HPH202? 37. How many bonds has the phosphorus in H3P02 ? 38. How many bonds does the phosphorus have in HOP02? 39. How many bonds does the phosphorus have in H2PH03? How many in H3P03 ? 40. How many bonds does the phosphorus have in H5P05? InH3P04? InHP03? 41. Give the technical names of all the phosphorus com- pounds represented by the formulas in questions 36-40. 42. What is the difference between the phosphorus in a metaphosphite and the phosphorus in any phosphate ? 43. Write the molecular formula for nitrate of arsenic. 44. Write the molecular formula for arsenous hydroxide. 45. If hydrogen arsenide is H3As, what possible combining values can the arsenic have when united to oxygen ? 46. Why is the formula for arsenous acid written H2HAs03 instead of H3As03 ? 47. Can that formula be written more scientifically than it is in either of the forms given in the preceding ques- tion? 48. Why is As203 not an acid? 49. Antimony is a very heavy, brilliantly metallic looking 206 A CORRESPONDENCE COURSE IN PHARMACY substance and forms several useful alloys. Why, then, is it not a metal, chemically as well as physically ? 50. What is an antimonide ? 51. What is the difference between antimonous oxide and antimonic oxide ? 52. Name several carbon compounds contained in the mineral world. 53. Mention several forms of free carbon found in nature. 54. What is the algebraic combining number of the carbon atominH3COH? 55. Why are the hydrocarbons so useful as fuel? 56. What is carbonic acid ? 57. What is carbonic acid gas ? 58. How is the 00^ exhaled by men and animals removed from the atmosphere ? 59. What is hydrocyanic acid ? 60. What is the algebraic combining number of the carbon in a molecule of the so-called hydrocyanic acid ? 61. What is silica? 62. What is the composition of glass ? 63. What are the principal uses of boric acid ? 64. What is the algebraic combining number of each boron atom in borax ? LESSON FIFTEEN To the Student: The section numbered XXIV, which treats of the solubilities of com- mon inorganic chemical compounds in water and in alcohol, is included in this lesson principally because of its value as a matter of reference for students. It is full of facts a knowledge of which the student should have, but as the mastering of it is a pure matter of memory, no questions are given upon it. It is not expected, moreover, that the student will memorize the chapter, but will keep it available for frequent reference in subsequent lessons, and it is certain that he will find the matter useful in examinations and in future work. XXII The Light Metals 321. The light metals are those whose specific weights are less than 5 and lower than the specific weights of their own oxides. The most important light metals are lithium, sodium, potassium, magnesium, calcium, strontium, barium and aluminum. All of these metals have a constant valence. 322. The alkali metals are lithium, sodium, potassium, rubidium and caesium. The two last mentioned are rare. Potassium and sodium are abundant. All of them are monads or have an atomic combining value of 1, for their oxides are Li20, Na20, K20, Kb20 and Cs20. Their hydroxides are the true alkalies, which are freely water-soluble. The alkali metals have such an intense affinity for oxygen that they must be excluded from contact 207 208 A CORRESPONDENCE COURSE IN PHARMACY with air, and this is effected by keeping them immersed in kerosene or benzin. When put in water they decompose it, combining with hydroxyl and liberating one hydrogen atom from each molecule of water decomposed : HOH + K = KOH + H. 323. Potassium is a soft silver-white metal, lustrous when freshly cut but tarnishing rapidly in the air. It is kept immersed in benzin to prevent its oxidation. The specific weight of K is 0.86. 324. Occurrence. Potassium is a widely distributed metal. Potassium silicate occurs in granite rocks, and plants grow- ing in the soils derived from such rocks yield an ash contain- ing potassium carbonate. This is leached out from wood ashes with water and the solution boiled down to get the crude potassium carbonate which is called "potash." The metal itself derives its name from the potash. Potassium is also contained in "argols" or crude "tartar," which is the bitartrate of potassium deposited from the fermenting grape juice in the process of making wine. Purified by recrystallization, the crude tartar is called "cream of tartar." But the present source of potassium is the potassium chloride associated with other salts in the salt beds at Stassfurt, Germany. 325. Potassium compounds are white or colorless unless they contain other elements which impart color. They are nearly all very readily water-soluble, and several common potassium compounds are, in fact, deliquescent. Among the most common compounds of potassium are: KOH, potassium hydroxide, called "caustic potash." K2C03, the carbonate of potassium, or "potash." KHC03, bicarbonate of potassium. KBr, potassium bromide. KI, potassium iodide. THE LIGHT METALS 209 KN03, potassium nitrate, or "niter," or " saltpetre." KCIO3, potassium chlorate. 326. Sodium is very like potassium, but does not decompose water so violently. Its specific weight is 0.97. It occurs abundantly in the form of common "salt," which is sodium chloride, in sea-water and in salt-springs and salt- beds. Sodium nitrate is found in Chili in the form called "Chili saltpetre." Common "washing soda" is sodium carbonate, which is manufactured on an immense scale from sodium sulphate made out of sodium chloride, or the carbonate may be made direct from sodium chloride. 327. Sodium compounds are white or colorless and generally very readily water-soluble. The most common include : NaOH, sodium hydroxide, or "caustic soda." Na2C03-l- 10II2O, sodium carbonate, which constitutes "sal sodae" or washing soda. NaHC03, sodium bicarbonate, or "baking soda." NaCI, "common salt." Na2SO4 + 10II2O, sodium sulphate, or "Glauber's salt." Na2S03S + 5H20, sodium thio- sulphate, commonly but erroneously called "hyposulphite of sodium" (which is Na2S02 — quite another substance). NaN03, sodium nitrate, or "Chili saltpetre." Na2HP04-f 12H20, sodium phosphate. Na2B4O7 + 10H2O, sodium tetraborate, or "borax." NaC18H3302, sodium oleate, the chief constituent of com- mon hard soap, such as "Castile soap." 328. Lithium is, like potassium and sodium, a soft silver- white metal. It is comparatively rare and costly. Its specific weight is 0.589. Its compounds are white or colorless. They are not as generally or freely soluble as the compounds of potassium 210 A CORRESPONDENCE COURSE IN PHARMACY and sodium. One of the most striking properties of lithium salts is the beautiful crimson color they impart to flame. 329. The Alkaline Earth Metals. These are barium, strontium and calcium. They have an atomic combining value of 2, for their oxides are BaO, SrO and CaO. The hydroxides of these metals are sparingly water-soluble, but the solutions have a strongly alkaline character. Like the alkali metals, they decompose water, but much more quietly. 330. Barium is a soft, yellowish metal of the specific weight 4. It occurs in "heavy spar," which is barium sulphate, in caves on Put-in-Bay Island, Ohio. The most common compounds of barium are : BaO, barium oxide, or "baryta." BaC03, barium carbonate. BaCl2 + 2H20, barium chloride. Ba(N03)2, barium nitrate. BaS04, barium sulphate. 331. Strontium is comparatively rare. It is a soft, yellowish metal having the specific weight 2.5. Its compounds are analogous to those of calcium and barium. 332. Calcium is a soft, yellowish metal of the specific weight 1.6. It may be kept in dry air without oxidation, but decomposes water rapidly : 2H20 + Ca = Ca(OH)2 + 2H. It occurs abundantly in the form of limestone, chalk and marble, all of which are calcium carbonate. Igneous rocks contain calcium silicate and other calcium compounds. "Gypsum" is calcium sulphate, and dried gypsum is nearly anhydrous or water-free calcium sulphate, which, when mixed with the proper amount of water, forms normal calcium sulphate, commonly called crystallized calcium sul- phate or "plaster of Paris." Quick lime, or building lime, is THE LIGHT METALS 211 calcium oxide, and slaked lime is calcium hydroxide. Hy- draulic cement is made by calcining limestone containing clay and silica; this cement hardens when mixed with water, forming calcium silicate and carbonate. 333. Calcium compounds are white or colorless. The car- bonate, phosphate and oxalate are insoluble ; hydroxide and sulphate are sparingly soluble. Among the most common calcium compounds are : CaO, calcium oxide, calx, or "lime." Ca(OH)2, calcium hydroxide, "slaked lime." "Lime water" is a solution of calcium hydroxide. CaCl2, calcium chloride. CaC03, calcium carbonate, marble, chalk, limestone. CaH4S06 (or CaS04 4-2H20), calcium sulphate or "gyp- sum." CaS04, dried calcium sulphate, used for making "plaster of Paris" by mixing the dry powder with water. Oa3(P04)2, calcium phosphate, which is the chief inorganic constituent of bone. Ca(C10)2, calcium hypochlorite, the valuable constituent of the so-called "chloride of lime" or "bleaching powder," which also contains CaCl2. 334. Magnesium is a white metal which oxidizes but slowly in moist air. Can be made into wire and ribbons, and con- verted into coarse powder. Its specific weight is 1.74. It does not decompose water at the ordinary temperatures, but does so at the boiling point of. the water. The "flash-light" of photographers is produced by burning powdered magnesium. Magnesium occurs in large quantities, chiefly in the form of carbonate and silicate. Magnesite is magnesium carbonate. "French chalk" or "talcum," and also "asbestos" and "meerschaum," are magnesium silicate. 212 A CORRESPONDENCE COURSE IN PHARMACY 335. Magnesium compounds are white or colorless. The oxide, hydroxide, carbonate, phosphate and oxalate are insoluble in water. The citrate is also practically insoluble in water, but the " solution of citrate of magnesium" of the drug stores is made by adding a large excess of citric acid, which holds the magnesium citrate in solution in the water. Among the most common magnesium compounds are: MgO, magnesium oxide, commonly called "calcined magnesia." MgH2S05 + 6H20 (commonly represented as MgS04 + 7H20) is magnesium sulphate, or "Epsom salt." Mg5(OH)2(C03)4 + 5H20 is the common carbonate of mag- nesium. 336. Aluminum is a silver-white metal which is malleable, ductile and capable of high polish. It is not tarnished in dry, pure air. Its specific weight is 2.5. It is strong, tough, durable and light, and as it does not corrode in the air and is not easily affected by other substances except chlorides, it is an extremely useful metal. This metal occurs abundantly in combination with oxygen and silicon. Clay consists of aluminum silicate. Cryolite is 3XaF. A1F3. Beauxite is A1203 + H20. Aluminum oxide, commonly called "alumina," occurs as emery, corundum, sapphire and ruby Feldspar. and mica contain aluminum, and "thina clay" or "pipe clay" or "kaolin" are also aluminum compounds. The metal is named after "alum." 337. Aluminum salts are white or colorless. Those soluble in water are astringent. The structure of aluminum compounds is illustrated by the following common compounds: A1203, aluminum oxide. Al(OH)3, aluminum hydroxide, commonly misnamed "aluminum hydrate." A1C13, aluminum chloride. THE HEAVY METALS 213 A1K(S04)2 + 12H20, aluminum and potassium sulphate, or alum, or " potash-alum." A1II4N(S04)2 4- 12H20, aluminum and ammonium sulphate, or "ammonia alum," the now common alum. XXIII The Heavy Metals 338. The heavy metals are those whose specific weights exceed 5 and are higher than those of their oxides. The heavy metals of great importance include zinc, iron, nickel, chromium, manganese, lead, copper, mercury, silver, gold, platinum, bismuth and tin. The compounds of the heavy metals are not as generally water-soluble as are the compounds of the light metals, and the compounds of metals of very high atomic weights as well as specific weights form very few water-soluble compounds. The light metals form more powerful bases than the heavy metals. 339. Zinc is a bluish-white, crystalline, lustrous, brittle metal of the specific weight 7.2. It melts at 412° C. It readily decomposes dilute acids, and also the alkalies in hot solutions. Zinc occurs as zinc Mende, which is sulphide of zinc, and also as calamine, which is composed of carbonate and silicate. 340. Zinc compounds are generally white or colorless. The water-soluble salts of zinc have a disagreeable, bitter, astringent, metallic taste, and are poisonous. Among the most common zinc compounds we have : ZnO, zinc oxide. ZnCl2, zinc chloride. ZnH2S05 + 6H20 (commonly represented as ZnS04 + 7H20) , zinc sulphate, or "white vitriol." 214 A CORRESPONDENCE COURSE IN PHARMACY 341. Iron is. light grayish, lustrous, hard, malleable, ductile, tenacious. Its specific weight is from 7.3 to 7.9. It melts at about 2000° C. Wrought iron, steel and cast iron all contain carbon and minute amounts of other elements. Wrought iron contains the smallest proportion of carbon ; cast iron the greatest. Iron occurs in very large quantities in the form of oxides, hydroxides, carbonates and sulphides. The best iron ore is "magnetic iron ore," which has a composition represented by Fe304. 342. Iron compounds are of various