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Classical Methods of Analysis
Strange as it may seem now, the analyst and the “works chemist” of the 18tli and 19th centuries depended almost entirely on what are frequently defined today as the classical methods of analysis, namely, gravimetric analysis and volumetric analysis. Gravimetric analysis is based on methods of determining the weights of the respective constituents of a product, whereas volumetric analysis is based on volumes rather than weights, the volumes being determined by a process known as titration — that is, determination of the strength of acid and basic solutions.
Difficult as the situation of the so-called “works chemist” during the industrial revolution was, it was not the sole reason for the dcclinc of the glamour and prestige of the analyst in the early days of the science of chemistry.
Following the logical sequence of events, it is not at all strange that chemist, having taken natural substances apart in order to determine their constituent elements, would then begin gradually to think about synthesizing in a test-tube, at least some of the useful things found in nature. The next logical step, of course, was to begin to think about producing tilings not found in the natural state. Thus, We had an evolution of researeh, principally in organic chemistry, directed towards synthesizing old or new compounds, chicfly the latter.
About halfway between World War I and World War II, the analytical chemist gradually began to experience a renaissance in his status withother members of the profession and with management. Quality became a very important factor in ever-increasing competitive markets. With this welcome change there came a demand for more rapid and more accurate methods of analysis. This demand led to a tremendous amount of researeh related to the broad field o f analysis. New scientific concepts were introduced, many of them based on what might be called physical chemistry.
Words and Word-Combinations to Be Memorized
canteen, department, event, excuse, frequently, gradually, lecture, a lot of, lots of, manage, market, profession, quality, respective, scientific, seminar, sequence, synthesize, test-tube, thank, tremendous, tube
Ex. 5. Give the Uzbek equivalents for the following:
depend on the classical methods, be defined as, gravimetric analysis, volumetric analysis, respective constituents, determine the volumes, the strength of acid and basic solutions, a difficult situation, the sole reason, in the early days of chemistry, following the sequence of events, experience a renaissance, competitive markets, introduce a concept
Ex. 6. Give the English equivalents for the following:
hamma narsani aniqlab olish g'alati tuyuladi, ammo bu juda qiyin, tabiiyki, in vitroda sintez qilishni, hech bo'lmaganda, keyingi bosqichni aniqlash uchun, tabiiyki, bu analitik kimyogar emas , tahlil qilishning yangi usullariga bo'lgan ehtiyoj, ko'pincha yo'naltirilishi kerak bo'lgan juda katta hajmdagi tadqiqotlar
Ex. 7. Fill in the blanks with articles where necessary.
1. In ... volumetric analysis... volumes were determined b y ... process known a s ... titration. 2.... situation o f ... so-called “works chemist” was rather difficult. 3. ... evolution o f ... researeh led to synthesizing old ornew compounds, chiefly... latter. 4 quality became... very importantfactor. 5. There came... demand for more rapid and more accurate methods of ... analysis.
Ex. 8. Give synonyms for the following:
at present, wholly, single, start, mainly, fast, wide, idea, producc, often
Ex. 9. Give antonyms for the following:
frequently, easy, late, together, at once, useless, revolution, old, the latter, decrease
Ex. 10. Translate the sentences into Uzbek.
1. Whenever an element is oxidized, some elements must be reduced.
2. Wherever sulphide ores o f the metals such as lead, copper, zinc may be found, there, too, We are likely to find sulphur compounds of arsenic.3. Strange as it may seem, considering its vital importance and the fact that it is around us everywhere, conscious acquaintance with oxygen dates back to only a little over two ccnturcs ago. 4. The energy involved in any reaction is usually called the heat of reaction, even though it may be electrical in nature. 5. The critical temperature is the highest temperature at which a vapour can be condensed to liquid by any pressure, however great it may be. 6. Whenever a person working in the laboratory mixes two or more substances and obtains a new product, he wants to know what has happened and what substances have been produced.
7. However that may be, the agreement between the two methods is satisfactory. 8. Important though it is, We shall not consider this ease now.
9. Crude though it is, this value is most frequently employed.10. Relatively little is known about the conditions of equilibrium which exist in the solid solution, whoever may say the opposite. 11. Whatever these observations may appear, such solutions obey Ohm’s law, just as metallic conductors do. 12. Simple though it actually is, this method has the advantage of being simple and flexible and of involving usually only moderately complicated considerations. 13. This technique remains unreliable, although it has recently been improved.
14. Whatever you may say, this circumstancc no doubt prevented earlier observers from accepting the concept. 15. Convenient as this method is, it has a drawback which involves a certain risk. 16. However that may be, We may raise the temperature and find a continuous scries o f equilibrium states. 17. Whenever a beam of white light is passed through a prism, it spreads it out into a spectrum containing all the colours from red to violet.18. Improbable though this case may appear at first glance, let us consider it in detail.
Ex. 11. Translate the sentences into English without using a dictionary.
1. Hozirda tahlilning ko'plab usullari qo'llanilmoqda. 2. Bunday klassik tahlil usullari gravimetrik tahlil va hajmli tahlildir. 3. Kimyogarlar avval ularning tarkibiy elementlarini aniqlash uchun tabiiy moddalarni ajratishdi. 4. Asta-sekin ular ba'zi foydali moddalarni labaratoriyada sintez qilish haqida o'ylay boshladilar. 5. Keyin ular keyingi bosqichga o'tdilar - mutlaqo yangi moddalarni sintez qilish. 6. Sifat talablarining oshishi tahlil usullarini yanada takomillashtirishga olib keldi.
Ex. 12. Answer the following questions:
1. What methods of analytical chemistry are called the classical methods o f analysis? 2. What is gravimetric analysis based on? 3. What is volumetric analysis? 4. How did chemists come to the idea of synthesizing a substance? 5. What stimulated the evolution of methods of analysis?
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