Санкт-петербургского государственного университета высшее профессиональное образование т. А. Степанова, И. Ю. Ступина
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Lesson 31 ГРАММАТИКА: Вводные члены предложения. Инфинитив н причастие в функции вводного члена предложения. Section I Ex. 1. Practise your reading. The terms “oxidation" and “reduction” now arc applied to reactions in which neither oxygen nor hydrogen arc involved. Ex. 2. State what parts of speech the following words belong to: oxide, oxidablc, oxidability, oxidant, oxidate, oxidation, oxidative, oxidic, oxidize, oxidizablc, oxidizability, oxidizer, oxygen, oxygenate, oxygenize, hydroxide, dioxide Ex. 3. Define the meanings of the word put in the following sentences: 1. Please,put this book on the shelf. 2. Put down the apparatus, never hold it in your hands during operation! 3. The idea was put forward that ozone is essential in protecting life on the Earth. 4. To put the instrument into operation press the red button. S. It seems to me that this is a utopian idea and it can never be put into practicc. 6. To put it in another way, these two terms mean the same. 7. Never put ofT till tomorrow what you can do today. Ex. 4. Analyse the following sentence: Strictly speaking, wc cannot say that wc know everything about oxidation. Text 31 A Oxidation and Reduction Generally speaking, the simple meanings o f these terms arc that oxidation is the addition of oxygen to a substancc and reduction is the 202 icmoval of oxygen. Needless to say, hydrogen seems to be the chcmical opposite of oxygen (the two elements combine readily, and arc evolved at opposite clcctrodcs during clcctrolysis). Removal of hydrogen is, therefore, similar to the addition of oxygen, and addition of hydrogen is similar to the removal of oxygen. Fuller meanings of the two terms arc therefore: Oxidation is the addition of oxygen to, or removal of hydrogen from, a substancc. Reduction is the removal o f oxygen from, or addition o f hydrogen to, a substancc. 2S02 + 0 2 2=5 2SOj (oxidation of S 02; addition of oxygen) PbO + Hj — Pb + HjO (reduction of PbO; removal of oxygen) Cl2 + H: — 2HC1 (reduction of Cl2; addition of hydrogen) H2S + Cl: ~ * Si + 2HCI (oxidation of HjS; removal of hydrogen) The terms now arc applied to reactions in which neither oxygen nor hydrogen arc involved. To take an example, the changc o f ferrous oxide to fcrric oxide is, obviously, an oxidation; similarly, wc can regard the changc of any ferrous compound to a fcrric compound as an oxidation (and a changc of fcrric to ferrous as a reduction): 4FcO + 0 2 — 2Fc:Oj; . FeCI2 + Cl2 — 2FeCb- Note that the valency o f the metal increases during oxidation. Metals and hydrogen form positive ions (c. g., Na' and H’) and arc, therefore, callcd clcctropositivc. Non-metals and acid radicals arc electronegative as they form negative ions (c. g., 0 :*, SQr')- Putting it another way, more complete definitions o f the two terms arc: Oxidation is the addition of any clcctroncgativc element or radical to, or removal o f any clcctropositivc element or radical from, a substancc. Reduction is the opposite. An oxidizing agent is a substancc which brings about oxidation, a reducing agent is a substancc which brings about reduction. Oxidizing agents includc: oxygen, hydrogen peroxide, nitric acid, sulphuric acid, chlorinc, potassium permanganate, potassium dichromatc. Reducing agents includc: hydrogen, carbon, carbon monoxide, sulphur dioxide, hydrogen sulphide, ammonia, and most metals and non-metals. The equations for the oxidation o f ferrous chloridc arc: 2FcCl: + Clj — 2FcCh; ionically: 2F to fcrric, it occurs by loss of an clcctron (c). And oxidation of chlorinc to chloridc ions takes place by gain of electrons: Fc:* - e — Fc}* (oxidation); Ch + 2To summarize, oxidation is the removal of electrons from a substancc. Reduction is the addition of clcctrons to a substancc. 203 An oxidizing agent is a substancc that acccpts clcctrons. A reducing agent is a substancc that supplies clcctrons. (Remember the word ORE — Oxidation is Removal o f Electrons.) Words and Word-Combinations to Be Memorized agent, e. g., evolve, generally speaking, loss, meaning, monoxide, needless to say, neither... nor, non-metal, opposite, permanganate, peroxide, put into operation, put into pracitce, put it (in) another way, put ofT, removal, remove, say nothing of, seem, summarize Ex. 5. Give the Russian equivalents for the following: the meaning o f the term, needless to say, combinc readily, a fuller meaning, add to, remove from, apply to, take an example, obviously, regard as, be the opposite, bring about oxidation, involve a change, by gain of clcctrons, by loss of clcctrons, accept, supply Ex. 6. Give the English equivalents for the following: вообще говоря, легко соединяться, выделяться на электроде, быть похожим на, следовательно, применять к реакции, ни... ни..., напри мер, подобным образом, заметим что, увеличивать валентность, ины ми словами, полное определение, азотная кислота, сульфид водоро да, аммиак, большинство неметаллов, как уже упоминалось, удаление электронов, окислитель, восстановитель Ex. 7. Fill in the blanks with articles where ncccssary. 1. ... oxidation is ... removal o f ... clcctrons from ... substancc. 2 oxidation o f... chlorinc t o ... chloride ions takes placc b y ... gain of ... clcctrons. 3. ... oxygen is ... oxidizing agent. 4. ... meanings o f ... terms ... oxidation and ... reduction arc considered here. 5 .... change of ... ferrous oxide to ... ferric oxide is obviously ... oxidation. Ex. 8. Give synonyms for the following: addition, readily, therefore, full, apply, take an example, changc, obviously, regard, includc, occur, take, give Ex. 9. Give antonyms for the following: complex, removal, opposite, decompose, reduction, decrease, positive, metal, incomplete, cxdude, loss, accept Ex. 10. Translate the sentences into Russian. 1. To anticipate a little, there arc several meanings o f the terms “oxidation” and “reduction”. 2. To be sure, any student can easily give an example of oxidation. 3. To begin with, one can say that the simplest meaning of the term “oxidation" is the addition of oxygen to a substancc 204 and reduction is the opposite. 4. Needless to say, this meaning is incomplete. 5. To sum up, relatively little is known about the state of solid solutions or the conditions of equilibria which exist therein. 6. To mention only one, wc shall consider in some detail the theory of electrolytic dissociation in its application to homogeneous equilibria. 7. Suffice it to say that similar results can be derived for other systems under investigation. 8. To put it in another way, the attraction between molcculcs varies inversely. 9. To tell the truth, these measurements vary so widely that it seems difficult to include them in this articlc. 10. Thorium, plutonium, mcndclcvium — not to mention uranium— belong to the actinoid series. 11. To summarize, no satisfactory equation for the proccss has been proposed. 12. The method is somewhat risky and not easily generalized, to say the least. 13. To put it more exactly, these values arc now regarded as normal. 14. To say nothing o f the details, an oxidizing agent is a substancc which brings about oxidation. IS. Metals and hydrogen form positive ions, that is to say, they arc electropositive. 16. To take an example, hydrogen and carbon arc reducing agents. 17. To illustrate, a change of ferrous ion to ferric takes placc by loss o f an electron. 18. One of the aims of education is to extend student’s views, his philosophy, so to say. 19. As emphasized above, this condition is satisfied automatically. 20. As already mentioned, wc find cases where solution occurs with evolution o f heat. 21. Roughly speaking, the conception of free ions affords very satisfactory explanation of all these phenomena. 22. Broadly considered, a heterogeneous system is one which consists o f more than one physical state. 23. Put another way, one molcculc gives rise to two smaller molcculcs or atoms. 24. Strictly speaking, it is for this reason that wc shall to a large extent limit ourselves to a brief consideration of a gaseous state. 25. As pointed out previously, the term “oxidation” has a long histoiy. 26. As stated above, the meaning of reduction is the opposite o f oxidation. 27. Generally speaking, oxidation is removal of electrons. Ex. 11. Translate the scntcnccs into English without using a dictionary. 1. Первое, о чем обычно думают, говоря об окислении, — это то, что окисление представляет собой присоединение кислорода. 2. Со ответственно , восстановление — это противоположный процесс. 3. Однако теперь э л 1 термины применяются и к реакциям, в которых ни кислород, ни водород не участвуют. 4. Современные понятия окис ления и восстановления связаны с переносом электронов. 5. Для хи мика окисление — это удаление электронов. Ex. 12. Answer the following questions: 1. What is the meaning of the term “oxidation”? 2. In what sense is hydrogen the chcmical opposite to oxygen? 3. Why is the change of any ferrous compound to a ferric compound regarded as an oxidation? 4. What is an oxidizing agent? 5. What is a reducing agent? 6. What arc the most common oxidizing and reducing agents? 205 |