Bài giảng Hóa học - Chương 5: Nhóm VA

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Bài giảng Hóa học - Chương 5: Nhóm VA

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Bài giảng cung cấp cho người học các kiến thức: Nhóm VA, sự chuyển dịch cân bằng, tính oxi hóa của nitrat, sự thủy phân, oxit và oxiaxit của photpho, điều chế chất,... Hi vọng đây sẽ là một tài liệu hữu ích dành cho các bạn sinh viên đang theo học môn dùng làm tài liệu học tập và nghiên cứu. Mời các bạn cùng tham khảo chi tiết nội dung tài liệu.

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  1. GROUP VA  Nitrogen N 7 [He]2s22p3  Phosphorus P 15 [Ne]3s23p3  Arsenic As 33 [Ar]3d104s24p3  Antimony Sb 51 [Kr]4d105s25p3  Bismuth Bi 83 [Rn]4f145d106s26p3 Department of Inorganic Chemistry - HUT
  2. Department of Inorganic Chemistry - HUT
  3. Department of Inorganic Chemistry - HUT
  4.  ĐẶC ĐIỂM CHUNG  NITO  Đơn chất  Amoniac  Oxit của nito  Nitrit  Axit nitric  PHOTPHO  Đơn chất  Oxit và oxiaxit của photpho  ASEN, ANTIMON, BITMUS Department of Inorganic Chemistry - HUT
  5. Department of Inorganic Chemistry - HUT
  6. PHI KIM GIẢM, KIM LOẠI TĂNG  Nitrogen N 7 [He]2s22p3 +V +III  Phosphorus P 15 [Ne]3s23p3  Arsenic As 33 [Ar]3d104s24p3  Antimony Sb 51 [Kr]4d105s25p3 +V  Bismuth Bi 83 [Rn]4f145d106s26p3 +III Department of Inorganic Chemistry - HUT
  7. Khả năng tạo liên kết • Nito tạo liên kết đơn, kép hoặc ba cộng hóa trị. • Nito nhận 3e tạo hợp chất nitrua với kim loại điển hình. • Các nguyên tố còn lại có AO nd trống nên tạo số OXH cao nhất. ns np 2 3 • Nito có khả năng tạo liên kết cho-nhận. Khả năng tạo liên kết cho nhận giảm nhanh từ N  Bi. Số oxi hóa • Nito có số OXH từ -III đến +V. • Hợp chất quan trọng có số OXH là +III và +V, riêng N có số OXH –III. Qui luật biến đổi • Từ N  P độ bền số OXH +III và +V tăng dần vì có AO nd tham gia liên kết. • Từ P  Bi độ bền số OXH +III tăng còn +V giảm dần do tính trơ của cặp ns tăng dần từ trên xuống. • Tính KH của X(III) giảm dần, tính OXH của X(V) tăng dần từ P  Bi.
  8. ĐẶC ĐIỂM CHUNG ∆H XCl3 (k ) + Cl2 (k ) XCl5 (k ) 3E X −Cl ECl −Cl −5E X −Cl Z X (k ) + 5Cl (k ) Z ∆H = 3E X −Cl ( XCl3 ) − 5E X −Cl ( XCl5 ) + ECl −Cl Department of Inorganic Chemistry - HUT
  9.  ĐẶC ĐIỂM CHUNG  NITO  Đơn chất  Amoniac  Oxit của nito  Nitrit  Axit nitric  PHOTPHO  Đơn chất  Oxit và oxiaxit của photpho  ASEN, ANTIMON, BITMUS Department of Inorganic Chemistry - HUT
  10. Mp = - 210 oC 941 kJ/mol Bp = - 196 oC (77 K) 1.095 Å ( KK )σ σ π = π σ 2 s *2 s 2 x 2 y 2 z 1 N = (2 + 2 + 2 + 2 − 2 ) = 3 * 2 Department of Inorganic Chemistry - HUT
  11. N N2 π − −π N * * x y 2p − − − −2p πx − −π y − −σ z − − σ s* 2s − − − − 2s − −σs Department of Inorganic Chemistry - HUT
  12. Nitrogen (Latin nitrum, Greek Nitron meaning "native soda", "genes", "forming") is formally considered to have been discovered by Daniel Rutherford in 1772, who called it noxious air or fixed air. That there was a fraction of air that did not support combustion was well known to the late 18th century chemist. Nitrogen was also studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air or phlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier referred to it as azote, from the Greek word αζωτος meaning "lifeless". Animals died in it, and it was the principal component of air in which animals had suffocated and flames had burned to extinction. This term has become the French word for "nitrogen" and later spread out to many other languages. Compounds of nitrogen were known in the Middle Ages. The alchemists knew nitric acid as aqua fortis (strong water). The mixture of nitric and hydrochloric acids was known as aqua regia (royal water), celebrated for its ability to dissolve gold (the king of metals). The earliest industrial and agricultural applications of nitrogen compounds used it in the form of saltpeter ( sodium- or potassium nitrate), notably in gunpowder, and much later, as Department of Inorganic Chemistry - HUT
  13. Simple compounds The main neutral hydride of nitrogen is ammonia (NH3), although hydrazine (N2H4) is also commonly used. Ammonia is more basic than water by 6 orders of magnitude. In solution ammonia forms the ammonium ion (NH4+). Liquid ammonia (b.p. 240 K) is amphiprotic (displaying either Brønsted-Lowry acidic or basic character) and forms ammonium and less commonly) amide ions (NH2-); both amides and nitride (N3-) salts are known, but decompose in water. Singly, doubly, triply and quadruply substituted alkyl compounds of ammonia are called amines (four substitutions, to form commercially and biologically important quarternary amines, results in a positively charged nitrogen, and thus a water-soluble, or at least amphiphilic, compound). Larger chains, rings and structures of nitrogen hydrides are also known, but are generally unstable. Other classes of nitrogen anions are azides (N3-), which are linear and isoelectronic to carbon dioxide. Another molecule of the same structure is dinitrogen monoxide (N2O), also known as laughing gas. This is one of a variety of oxides, the most prominent of which are nitrogen monoxide (NO) (known more commonly as nitric oxide in biology) and nitrogen dioxide (NO2), which both contain an unpaired electron. The latter shows some tendency to dimerize and is an important component of smog. The more standard oxides, dinitrogen trioxide (N2O3) and dinitrogen pentoxide (N2O5), are actually fairly unstable and explosive. The corresponding acids are nitrous (HNO2) and nitric acid (HNO3), with the corresponding salts called nitrites and nitrates. Nitric acid is one of the few acids stronger than hydronium, and is a fairly strong oxidizing agent. Nitrogen can also be found in organic compounds. Common nitrogen functional groups include: amines, amides, nitro groups, imines, and enamines. The amount of nitrogen in a
  14. Nitrogen compounds of notable economic importance Molecular nitrogen (N ) in the atmosphere is relatively non-reactive due to its 2 strong bond, and N2 plays an inert role in the human body, being neither produced or destroyed. In nature, nitrogen is slowly converted into biologically (and industrially) useful compounds by some living organisms, notably certain bacteria (i.e. nitrogen fixing bacteria - see Biological role above). Molecular nitrogen is also released into the atmosphere in the process of decay, in dead plant and animal tissues. The ability to combine or fix molecular nitrogen is a key feature of modern industrial chemistry, where nitrogen and natural gas are converted into ammonia via the Haber process. Ammonia, in turn, can be used directly (primarily as a fertilizer, and in the synthesis of nitrated fertilizers), or as a precursor of many other important materials including explosives, largely via the production of nitric acid by the Ostwald process. The salts of nitric acid include important compounds such as potassium nitrate (or saltpeter, important historically for its use in gunpowder) and ammonium nitrate, an important fertilizer and explosive (see ANFO). Various other nitrated organic compounds, such as nitroglycerin and trinitrotoluene, and nitrocellulose, are used as explosives and propellants for modern firearms. Nitric acid is used as an oxidizing agent in liquid fueled rockets. Hydrazine and hydrazine derivatives find use as rocket fuels. In all of these compounds, the basic instability and tendency to burn or explode is derived from the fact that nitrogen is present as an oxide, and not as the far more stable nitrogen molecule (N 2) which is a product of the compound's decomposition. When nitrates burn or explode, the formation of the powerful triple bond in the N2 which results, produces most of the energy of the reaction. Nitrogen is a constituent of molecules in every major drug class in pharmacology and medicine. Nitrous oxide (N20) was discovered early in the 19th century to be a partial anesthetic, though it was not used as a surgical anesthetic until later. Called "laughing gas", it was found capable of inducing a state of social disinhibition resembling drunkenness. Other notable nitrogen-containing drugs are drugs derived from plant alkaloids, such as morphine (there exist many alkaloids known to have pharmacological effects; in some cases they appear natural chemical defences of plants against predation). Nitrogen containing drugs include all of the major classes of antibiotics, and organic nitrate drugs like nitroglycerin and nitroprusside which regulate blood pressure and heart action by mimicing the action of nitric oxide.
  15. Multi-Industry Uses: The inert properties of nitrogen make it a good blanketing gas in many applications. Nitrogen blanketing is used to protect flammable or explosive solids and liquids from contact with air. Certain chemicals, surfaces of solids, and stored food products have properties that must be protected from degradation by the effects of atmospheric oxygen and moisture. Protection is achieved by keeping these items in (under) a nitrogen atmosphere. "Inerting" or "padding" are other terms used to describe displacement of air and nitrogen blanketing. "Sparging" with nitrogen is the bubbling of nitrogen through a liquid to remove unwanted volatile components, including volatile organic compounds (VOC) which may be necessary to meet pollution reduction regulations. Certain substances are difficult to pulverize or shred because they are tough or the materials will be degraded by the heat generated by mechanical processes such as grinding. Liquid nitrogen can be used to freeze soft or tough substances prior to their entering a size reduction process. Cold vaporized nitrogen can be used to keep materials cool (and in an inert atmosphere) during grinding. Cryogenic grinding is used in diverse applications, including production of finely ground pharmaceuticals, plastics and pigments; and for shredding tires in recycling plants. Materials become hard and brittle when cooled by to very low temperatures. This property permits the removal of “flash” or “fins” on cast plastics and rubber. The castings are cooled by liquid nitrogen and the flash broken off by mechanical action. Department of Inorganic Chemistry - HUT
  16. Metals: Nitrogen is used to treat the melt in the manufacture of steel and other metals and as a shield gas in the heat treatment of iron, steel and other metals. It is also used as a process gas, together with other gases for reduction of carbonization and nitriding. “Flash” or “fins” on cast metal can be removed by cooling with liquid nitrogen, making them brittle, allowing then to be broken off by mechanical action. Manufacturing and Construction: Shrink fitting is an interesting alternative to traditional expansion fitting. Instead of heating the outer metal part, the inner part is cooled by liquid nitrogen so that the metal shrinks and can be inserted. When the metal returns to its normal temperature, it expands to its original size, giving a very tight fit. Liquid nitrogen is used to cool concrete, which leads to better cured properties. When construction operations must be done in soft, water-soaked ground such as tunnel construction underneath waterways, the ground can be frozen effectively with liquid nitrogen. Pipes are driven into the ground, liquid nitrogen is pumped through the pipes under the earth’s surface. When the nitrogen exits into the soil, it vaporizes, removing heat from the soil and freezing it.
  17. Chemicals, Pharmaceuticals and Petroleum: Refineries, petrochemical plants and marine tankers use nitrogen to purge equipment, tanks and pipelines of dangerous vapors and gases (for example, after completing a pipeline transfer operation or ending a production run) and to maintain an inert and protective atmosphere in tanks storing flammable liquids. Cold nitrogen gas is used to cool reactors filled with catalyst during maintenance work. The cooling time can be reduced substantially. Cooling reactors (and the materials inside) to low temperature allows better control of side- reactions in complex reactions in the pharmaceutical industry. Liquid nitrogen is often used to provide the necessary refrigeration as it can produce rapid temperature reduction and easily maintain the required cold reaction temperatures. Reactor cooling and temperature control systems usually employ a circulating low-temperature heat transfer fluid to transfer refrigeration produced by vaporizing liquid nitrogen to the shell of the reactor vessel. The liquid nitrogen is vaporized in specially-designed heat exchangers that transfer refrigeration to the circulating heat transfer fluid. Liquid nitrogen is used during well completion to "frac" natural gas bearing rock formations, in particular, tight gas formations, including shale gas and natural gas from coal (coal bed methane) where water based methods should be avoided. Nitrogen is also used to maintain pressure in oil and natural gas producing formations. Unlike carbon dioxide, which is also used for pressurization, nitrogen has little affinity for liquid hydrocarbons, thus it builds up in and remains in the gas cap. Nitrogen is used an inert gas to push liquids though lines, to clear lines and to propel "pigs" through pipelines to sweep out one material before using the line to transport another material. Rubber and Plastics: Materials become hard and brittle when cooled by to very low temperatures. This property permits the removal of “flash” or “fins” on cast plastics and rubber. The castings are cooled by liquid nitrogen and the flash broken off by mechanical action.
  18. Food and Beverages: The intense cold in liquid nitrogen allows very rapid freezing of food items, resulting in minimal cell damage from ice crystals and improved appearance, taste and texture. Well-designed cryogenic tunnel and spiral freezers efficiently capture refrigeration from liquid vaporization and from the cold nitrogen gas as it flows through the freezer. When substances such as vegetable oil and wines are stored, the inert properties of nitrogen can be used to protect against loss of quality by oxidation by expelling any air entrained in the liquid (“sparging”) and protecting liquids in storage tanks by filling the vapor space (“blanketing”). Nitrogen (and nitrogen mixed with CO2 and oxygen) is used in transport trucks and in Modified Atmosphere Packaging (MAP) to extend the shelf life of packaged foods by preventing oxidation, mold, insect infestation and moisture migration. Health Care: Nitrogen is used as a shield gas in the packing of some medicines to prevent degradation by oxidation or moisture adsorption. Nitrogen is used to freeze blood, as well as viruses for vaccination. It is also used to freeze livestock semen, which can then be stored for years. The quick freezing resulting from the intense cold minimizes cell wall damage. Liquid nitrogen is also used in some MRI (Magnetic Resonance Imaging) devices to pre-cool the low temperature magnets prior to using much more expensive liquid helium for final cooling. Liquid nitrogen is used in cryo-surgery to destroy diseased tissue. Miscellaneous: Nitrogen is used directly as a coolant for severe environmental testing of many items, or as a refrigeration source for chilling circulating dry air.
  19. o NH 4 NO2 t C N 2 + 2 H 2O o 2 NaN 3 t C 3 N 2 + 2 Na Department of Inorganic Chemistry - HUT



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