Санкт-петербургского государственного университета высшее профессиональное образование т. А. Степанова, И. Ю. Ступина
жүктеу/скачать 5,96 Mb. Pdf көрінісі
|
1stepanova t a english for chemists
| Scction II
Упр. 1. Прочтите заголовок и подзаголовок текста 5 В. Вспомните и скажите, что вы уже знаете по данной теме. Упр. 2. Назовите значения следующих интернациональных слов: radiation, ultraviolet, ozone, electric, arc, generation, electrolysis, concentration, efficiency, characteristic, detect, toxicity, molecule, linear, contract, diamagnetic, resonance, clcctrophilic, mechanistic, biological, effect, vitamin, observation, antioxidant, protection, destructive, elastomer Упр. 3. Определите значения выделенных слов по контексту. Сино нимы в скобках помогут вам. 1. Electrolysis is one o f the common (usual) methods for obtaining ozone. 2. The ultraviolet radiation technique (method) is used when relatively (comparatively) low concentrations arc obtained. 3. When high- 37 purity ozone is desired (is necessary), liquid ozone is used. 4. When water is boiling, vapour is formed. 6 . The normal atmospheric pressure is 760 mm. 7. The characteristic odour o f ozone is detcctablc by nose. 8 . This odour provides (gives) a warning (a signal) of toxicity. 9. On exposure to oxygen metals arc oxidized. 10 . Gaseous ozone possesses four resonance structures. 11. Elcctrophilic nature o f ozone is accounted fo r (explained by) this fact. Слова к тексту: silent discharge — тнхнй разряд; require — требовать; environment — окружающая среда; pass through a vessel — проходить через сосуд; bond — связь; rat — крыса; undergo — подвергаться Text 5 В Прочтите текст про себя (контрольное время чтения — 7 минут). Ozone: Properties, Toxicity, and Applications Common methods for ozone generation arc ultraviolet radiation, silent electric arc discharge and electrolysis. The unltraviolct radiation technique is used only when relatively low concentrations arc required, c. g. for environmental study. The electrolysis of water is not widely used bccausc of its low efficiency. So far, the action of silent clcctric discharge on oxygen is the most common method for the production of ozone. It gives a yield of 6 % by weight of ozone. When high purity or quantity of ozone is desired, it is possible to use liquid ozone. The ozonc-oxygcn mixture from one of the above methods is passed through a vessel at liquid oxygen temperature (-183°C). Because o f the large difference in the vapour pressure of ozone and oxygen, oxygen is pumped off from the mixture whereas ozone is liquefied. Liquid ozone is then vaporized from the concentrated system for further use. Ozone is a colourless gas with characteristic odour which is detectable by nose and provides a warning o f toxic exposure. The ozone molecule is non-linear with a bond angle o f 116°. In contrast to oxygen, gaseous ozone is diamagnetic and possesses four resonance structures with (III) and (IV) accounting for its elcctrophilic nature. 0» 0* 0 0 / \ / \ / \ / \ жүктеу/скачать 5,96 Mb. Достарыңызбен бөлісу:
|