English for chemists

Lesson 17
ГРАММАТИКА: ГерундиГ! н герундиальный оборот в функции подле­ жащего.
I Section I
Ex. 1. Practise your pronunciation.

1. 
   equal ['i:kwol], pressure ['prcfo], consequence ['konsikwons], gaseous ['gasiosj, weight [weitj, cohesion [кэо*Ы:зоп], adjaccnt [o'dseisant], average ['asvands], neighbour ['neibo], vary ('vcon], cause [ko:z], measure [*тезэ], throughout ['0ru:aotj, obviously ('obviosli], above [э'Ьлу]
   

2. 
   thef4moleculcs,at4,the(J'same\pressurc, through the \ycars, as^'those^injaNgas, 'tend^to \form, a'bove^,the\Hquid
   

3. 
   The 'molecules in a ‘liquid | are 'not 'all ‘moving at the 'same ve\locity.
   

Ex. 2. Pay attention to the structure of the following words. Translate them into Russian.

1. 
   overheat, overpressure, overgrow, overcome, ovcractivc
   

2. 
   non-crystallinc, non-metal, non-metal lie, non-standard, non-existent, non-agrcssivc, non-conductor, non-efTcctivc, non-ferrous
   
3. 
   outer, outwards, outstanding, output, outlet, outdoors, outcomc, out-of-date, out-of-work, outdated, throughout
   

Ex. 3. Define the meaning of the word result in the following sentences:
1. The results of this experiment are extremely important for our future work. 2. As a rule, heating liquids results in their expansion. 3. It is necessary to test the obtained result by using another approach. 4. The production of the ions results from passing high energy radiation through atoms of the gas within the container. 5. The temperature rise results in the increase in kinetic energy of the molcculcs taking part in the reaction. 6. Investigation of such analogies resulted in the development of the nitrogen system of compounds.
Ex. 4. Find the predicate and the subject in the following sentences:
1. According to Avogadro’s principle, the gram-molecular weight of any gaseous substance occupies 22.4 litres at standard temperature and pressure. 2. Liquids flow as a stream and tend to form drops to a greater or less extent. 3. Heating often results in the expansion of a body. 4. Boiling can be accomplished by raising the temperature of the liquid or by reducing the pressure of the atmosphere above the liquid.
Text 17 A
Molecules in Gases and Liquids
According to Avogadro’s principle, equal volumes of gases regardless of composition, contain the same number of molecules at the same temperature and pressure. As a consequence of the principle, the gram-molccular weight of any gaseous substancc occupies 22.4 litres at standard temperature (0°C) and pressure (760 mm of mercury). The number of molcculcs per gram-molc has been calculated by different methods of increasing refinement through the years, and is now considered to be 6.023x10“ atoms per gram-atom, or molcculcs per gram-molc), and it is accuratc within 0.1%. For example, one mole of ammonia gas'(NH) — weighs 17.073 grams, occupics a volume of 22.4 litre at standard temperature and pressure, and contains 6.023x10й molcculcs).
At the same temperature, molccules of a liquid move at the same rate as those in a gas. In a liquid, however, the extent of motion must be more restricted. Liquids flow as a stream and tend to form drops to a greater or less extent, thus giving evidence of the importance of the force of cohesion between the molecules in a liquid. Heating liquids, as a rule, results in their expansion, an effect explained by the tendency of the molcculcs to occupy more space when they move at a faster rate. Also, increase in pressure has but slight cffcct on the volume compressible. From this evidence it is argued that molcculcs in a liquid are ajaccnt, close enough to flow in a continuous stream.
The molecules in a liquid, like those in a gas, are not all moving at the same velocity, but at the same average velocity at a given temperature. The molcculcs at the surface of a liquid, unlike those below the surface

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layer, have no force of attraction from molcculcs above. Some of the more rapidly moving molcculcs overcome the cohcsivc force of their neighbour and leave the surface. The tendency to leave the surfacc or to evaporate varies from liquid to liquid, and it increases when the temperature is raised. The pressure causcd by the evaporation of molcculcs from a liquid, measured at equilibrium with the returning molcculcs at a given temperature, is callcd the vapour pressure. In general, vapour pressure increases when the temperature rises. With continued addition of heat the vapour pressure rises still more until the vapour pressure reaches the vapour pressure of the atmosphere above the liquid. The evaporation goes on throughout the liquid, and the liquid is boiling. Obviously the act of boiling can be accomplished either by raising the temperature of the liquid or by reducing the pressure of the atmosphere above the liquid.
W ords and W ord-Com binations to Be M emorized
accomplish, ammonia, attraction, average, compress, consequence, equal, equilibrium, evaporation, expansion, extent, fast, flow, go on, layer, litre, mercury, motion, the number of, obviously, occupy, overcome, per, pressure, principle, raise, rate, reducc, regardless of, restrict, result in, return, as a rule, stream, tend, tendency, throughout, unlike, vapour, velocity, weight
Ex. 5. Give the Russian equivalents for the following:
as a consequence of this principle, the gram-molecular weight, calculate by different methods, be accurate within 0.1 %, move at the same rate, to a greater extent, give cvidcncc of, the force of cohesion, from this cvidcncc, flow in a continuous stream, below the surface layer, overcome the force, rise still more, throughout the liquid, accomplish the boiling, either... or...,

* reduce pressure

Ex. 6. Give the English equvalents for the following:
равный объем, независимо от состава, одинаковое число моле-кул, при температуре, под давлением в одну атмосферу, быть ограни­ ченным, в меньшей степени, таким образом, нагревание жидкости, как правило, приводить к, двигаться с большой скоростью, оказы­ вать влияние на, со срсднсй скоростью, при данной температуре, на поверхности жидкости, в отличие от, сила притяжения, тенденция к испарению, достичь атмосферного давления, продолжать нагревание, очевидно, или... или...
Ex. 7. Fill in the blanks with prepositions where necessary.

1.	Liquids turn to form drops ... a greater or less extent. 2. One mo
... ammonia gas weighs...		17.073 grams, occupics a volume... 22.4 litres
... standard temperature and pressure. 3. The number ...				molcculcs ...
gram-molc was calculated...		different methods. 4....	the same temperature,

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molcculcs ... a liquid move ... the same rate as those ... a gas. S. The effect ... increasing pressure ... the volume ... a liquid is only slight. 6. The tendency to evaporate varies ... liquid ... liquid. 7. ... general, vapour pressure increases when the temperature rises.
Ex. 8. Translate the sentences into Russian, paying attention to different functions of as.