Санкт-петербургского государственного университета высшее профессиональное образование т. А. Степанова, И. Ю. Ступина
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1stepanova t a english for chemists
| Scction II
Упр. 1. Назовите значения следующих интернациональных слов: attractive, motion, total, diameter, extremely, distance, characteristic, operate, gram, atmosphere, temperature, ordinary Упр. 2. Определите зиачсиия выделенных слов по контекст}'. 1. How many times have you been to Moscow? 2. The specimen was analysed and it became clear that it contains copper. 3. What size arc your boots? 4. On the one hand, the proccss is rather simple, on the other hand, there is some difficulty bccausc the temperature must be very high. Слова к тексту: negligibly — ничтожно; apart — отдельно, в стороны друг от друга; accordingly — соответственно Text 18 В Прочтите текст про себя (контрольное время чтения — 3 минуты). The Nature of a Gas That the molcculcs of a gas arc not held together, but arc moving freely in a volume rather large compared with the volumes of the molcculcs themselves is the characteristic feature of a gas. The Van dcr Waals attractive forces between the molcculcs still operate whenever two molcculcs comc close together, but usually these forces arc negligibly small bccausc the molcculcs arc far apart. Bccausc of this freedom of molccular motion, a specimen of a gas docs not have either definite shape or definite size. A gas shapes itself to its container. Gases at ordinary pressure arc very dilute: the molcculcs themselves constitute only about one-thousandth of the total volume of the gas, the rest being empty space. Thus, 1 g of solid iodine has a volume of about 0.2 cm5 (its density is 4.93 g/cmJ), whereas 1 g of iodine gas at 1-atm pressure and at the temperature of 184°C (its boiling point) has a volume of 148 cmJ, over 700 times greater. The volume of all the molcculcs in a gas at ordinary pressure is accordingly small compared with the volume of the gas itself. On the other hand, the diameter of a gas molcculc is not extremely sniall compared with the distance between molcculcs; in a gas at room temperature and 1-atm pressure the average distance from a molcculc to its nearest neighbours is about ten times its molecular diameter. Упр. 3. Передайте основное содержание текста в нескольких пред ложениях. Упр. 4. Составьте план текста. Упр. 5. Прочтите предложения и скажите, соответствуют ли они содержанию текста. Если нет, исправьте их. 1. Molecules of a gas move freely in a volume o f its container. 2. The Van dcr Waals forces don’t act between the molcculcs of a gas. 3. The molcculcs of a gas arc rather elose together at ordinary pressure. 4. The volume occupicd by a gas is considerably greater than the volume of a solid of the same element. 5. The distance between the molecules of a gas at 1 -atm pressure is greater than the diameter of the molcculc itself. 6. The temperature has no influence on the gas volume. Упр. 6. Найдите в тексте и переведите на русский язык предложения в которых содержится описание самого отличительного свойства газа. жүктеу/скачать 5,96 Mb. Достарыңызбен бөлісу:
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