Англ, Determination of the Molecular Weight of a Gas

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Вариант 2
I Перепишите предложения и переведите их, обращая внимание на местоимение.
1. He makes no attempts to establish any contacts with our group, so I understand he got no such orders.
2. No explanation was given to him why the experiment had been stopped.
3. The scientists believe that there is practically no atmosphere on the Moon.
II. Перепишите предложения и переведите их, учитывая особенности перевода определений, выраженных именем существительным.
1. The vaporization process requires the addition of heat to the liquid.
2. Special attention was paid to the aluminum advantages — it is light, it does not rust, and is very strong especially when mixed with other metals.
3 It has been proved that destruction of tropical forests is reducing the carbon dioxide quantity.
III. Перепишите предложения и переведите их, обращая внимание на числительные.
1. Matter can occupy three different states — gas, liquid and solid.
2. In 1896, one year after the discovery of X-ray by Roentgen, a French physicist, Becquerel, discovered that uranium emits rays similar to those of X-rays; these rays were called "Becquerel rays".
3. It is five hundred times more expensive than iron, fifty times more expensive than copper, but is only worth one-fiftieth as much as platinum and one-twentieth as much as gold.
IV. Перепишите предложения и подчеркните в них модальный глагол или его эквивалент. Переведите предложения.
1. Like other substances, water can exist as a liquid, as a gas, or as a solid.
2. After they had found the composition of water, the scientists could investigate its properties.
3. It should be mentioned that the gamma-rays of radium are of shorter wave length than аny other form of radiant energy could be.
4. A first-year student has to carry out a number of drawers.
5. They have to found out the solubility of this substance.
6. This experiment is to be carried out again, the results are wrong.
7. On every laboratory bench one can see test-tubes, flasks, beakers, evaporating dishes, weighing bottles.
8. All this glassware should be kept in good order.
9. Space scientists need to know how much oxygen must be supplied to keep the astronauts alive.
10. The dispersing action of water on an ionic solid may be explained in terms of the polar nature of its molecules.
V. Перепишите предложения, подчеркните в них сказуемое и определите его видовременную форму и залог. Переведите предложения, обращая внимание на пассивные конструкции.
1. Chemistry is also related to biology, the science of life, because life itself is basically a complicated system of interrelated chemical processes.
2. Chemistry may be broadly classified into two main branches: organic chemistry (the chemistry of living things) and inorganic chemistry (the chemistry of nonliving things).
3. Many of basic concepts can be learned in a relatively short period of time.
4. The problem will be solved tomorrow.
5. At last he returned to the little town where his childhood had been spent.
6. Before the experiment the substances are mixed in a large cup.
7. This instrument is preferred to all others because of its great reliability.
8. The results of the last experiment were constantly referred to by the professor.
9. What question is being discussed now?
10. The experiments were still being conducted in some laboratories when the new term began.

Additional information

VI. Письменно переведите текст.
The Determination of the Molecular Weight of a Gas
The value of the molecular weight of a substance is of interest for several reasons. Ultimate analysis of a substance (the determination of the component elements and their amounts) provides knowledge of possible formulas but does not select the correct one; thus phosphorus trioxide, with composition corresponding to the simplest formula P2O3, actually consists of molecules Р4O6. Our understanding of atoms bonding together in molecules can be obtained only if the correct molecular formulas are known. Also in calculating the amounts of substances involved in reactions it is often convenient to deal with the volumes of gases; after its molecular weight being determined, the volume of a given weight of a gas can be calculated directly from the perfect-gas equation. The two methods employed most frequently are those of Dumas and Victor Meyer. In the former method the density (and hence the molecular weight) of a substance which is a gas under ordinary conditions is usually determined by weighing a flask of known volume filled with the gas under known pressure, and then the mass of the gas in the bulb is obtained by subtracting the mass of the evacuated glass bulb from the mass of the bulb when tilled with the gas. In ordinary work the second weighing may be replaced by a weighing of the flask filled with air, oxygen, or other gas of known density. The volume of the flask is determined by weighing it filled with water.


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