Санкт-петербургского государственного университета высшее профессиональное образование т. А. Степанова, И. Ю. Ступина
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| Section II
Упр. 1. Назовите значения следующих интернациональных слов: container, limit, crystalline, vibration, oscillation, crystal, phenomenon, sublimation, dioxide, camphor, sublime, coulomb, graphite, hexagonal, hexagon, associate, fix Упр. 2. Определите значения выделенных слов по контекст}'. 1. Water turns into ice at 0°C. 2. The temperature at which a solid changes into a liquid is callcd its melting point. 3. Repeat the rule several times, then you will remember it. 4. H2S 04 is apparently a more complex ( compound than H2S. Слова к тексту’: shape—форма; bound— ограничивать; dihedral— образованный дву мя плоскостями, гранями; confine — ограничивать; dry — сухой; tie — связывать Text 17 В Прочтите текст про себя (контрольное время чтения — 4 минуты). Molecules in Solids Having their own shape is a characteristic feature of solids sincc they have their own shape rather than that of the container (as for liquids and gases) and generally do not flow, the extent o f molccular motion in a solid is even more limited than that in a liquid. True solids arc crystalline, bounded by plane surfaces that meet in a definite dihedral angle, and have a characteristic melting point. The molcculcs in a solid have the same temperature, and if they arc molcculcs o f the same 121 substancc, they arc moving at the same average velocity, the motion o f molcculcs in a solid must be confined, and, probably, it is a vibration or oscillation about a fixed point. Crystals composed of molcculcs may evaporate in a manner similar to that of liquids. This phenomenon is callcd sublimation, and it may.be noticcd in solid carbon dioxide (dry icc), paradichlorobcnzcnc, camphor, and many odorous solids. Non-molccular solids show little tendency to sublime. The Van dcr Waals force between the particles in molecular solids is, apparently, less in general than the coulomb forces between ions in non-molccular solids. As with liquids, solids vary greatly in their tendency to sublime, and the rate of sublimation varies with the temperature and inversely with the pressure. In some solids the ciystal is composed of molcculcs in a pattern that repeats. Упр. 3. Передайте основное содержание текста в нескольких пред ложениях. Упр. 4. Составьте план текста. Упр. 5. Прочтите предложения и скажите, соответствуют ли они со держанию текста. Если нет, исправьте их. 1. Liquids and gases usually have the form of their container. 2. Characteristic feature o f solids is that they have their own form. 3. Crystalline solids cannot evaporate like liquids. 4. Sublimation is the evaporation of solids. 5. The rate of sublimation increases with the rise of the temperature and the pressure. 6. Planar structure o f the carbon atoms in graphite makes its properties different from those o f a diamond. Упр. б. Найдите в тексте и переведите на русский язык предложе ния, в которых говорится о движении молекул внутри вещества. жүктеу/скачать 5,96 Mb. Достарыңызбен бөлісу:
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