Impossible, rain, scale.
Water is not the most... compound, but it is also very important for...
Life would be ... without water.
The purest natural water is...
Ground water also contains a great deal of...
It is very important to obtain ... water.
Water for steam boilers should be ... from substances that cause . . . and ...formation.
Water for ... should not contain substances which react with soap.
Water for drinking should not contain.
There are three methods of water purification, that is and . . .
Ex. 12. Translate the following sentences:
Вода очень важна для жизни.
Жизнь была бы невозможна без воды.
Вода реагирует со многими веществами.
Для многих целей вода должна быть чистой.
Самая чистая природная вода - это дождь.
Однако она не является действительно чистой.
Подземная вода также содержит много примесей.
Чистая вода должна использоваться для паровых котлов, питья, умывания, в лабораториях и промышленности.
Два простейших метода очистки - это фильтрование и кипячение
Вода легко превращается в пар.
Конденсация пара дает чистую воду.
Ex. 13. Speak on the topics given before the text.
Lesson 9
Ex. 1*. Read the words. Try to translate them wuthout a dictionary:
Temperature Factor
Concentration Speed
Catalyst Kinetic
Reaction Molekule
Experiment Energy
Accelerate Period
Ex. 2*. Find nouns corresponding the following words, translate them:
important, uselessly, form, crystallize, evaporate, resemble, require, mean, difficult.
Ex. 3. Group the synonyms and translate them into Russian: influence, speed affect, involve, frequently, include, since, rate, because, often.
Ex. 4. Group the antonym sand translate them into Russian:
increase, high, absent, fall, decrease, fast, low. often, rise, likely, present, retard, slow, seldom, unlikelv. accelerate.
Ex. 5*. Check up if you remember the following words: naturally, in general, hence, some, in other words, number, quickly, commercially, frequently, sufficient, pay attention, consider, point of view, volume, amount, result in.
Ex. 6. Translate the sentences. Remember the meaning of the following words:
... is affected by ... - на ... влияет
mean - средний, означать
means - способ, средство
time - время, раз
the ... the - чем ... тем (с прилагательным в сравнительной степени)
The more surface of the material is exposed to the air. the more rapidly burning takes place.
After this process was repeated hundreds of times, the required data were obtained.
The molecular formulas of compounds are determined by chemical means.
For our experiment we must find the means of several temperature measure ments.
The more carbon the steel contains, the harder it becomes.
The solubility of a substance means the amount of that substance which will dissolve in a specified solvent.
Gold is hardly affected by nitric, sulphuric and hydrochloric acids.
The speed of the reaction increases two or three times.
The state of water, not its composition is affected by the process of heating or cooling.
It is necessary to remember that molecules possess kinetic energy which means that they are in constant motion.
Ex. 7. Refresh your grammar. Remember the construction "for + существительное + инфинитив". Translate the sentences.
A large proportion of the methods for the analysis of inorganic substances to be investigated involves treating an aqueous solution of the substance with known chemicals.
For the remarkable properties of rubber to be carefully examined, one should carry out a long series of experiments.
We applied heat for water to expland.
This problem is too difficult for the designers to solve in a year or two.
For a system to be in complete equilibrium, it is necessary that there will be mechanical equilibrium.
It is desirable to perform a quantitative analysis and a moleculas weight de termination for an unknown organic compound to be identified.
A catalitic agent, the presence of which is often necessary for the reaction to begin, is moisture.
Some time is required for the equilibrium between two different molecular species of sulphur to be established.
For two molucules to react they must come into contact.
For hydrogen to be obtained from water electrolysis may be used.
EX. 8. Read and translate the text.
FACTORS THAT INFLUENCE REACTION RATE
It is often very important to know under what conditions will
two substances react sufficiently rapidly for the reaction to be of practical use.
Therefore, when making experiments, account is to be taken of the factors that influence the rate of the reaction. Attention should be paid to the fact that reaction rate is affected by temperature, concentration, catalysis and so on. Let us consider these factors Temperature. In general the speed of a reaction increases two or four times for a rise of 10° in the temperature of the substances involved in the reaction.
The effect of the change of temperature can be readily understood from the kinetic molecular point of view.
The velocities of the molecules are increased as the temperature rises.
Faster moving molecules meet more often and being of higher energy content are more likely to react on meeting. Hence the rise of temperature gives more opportunity for the molecules to react and results in the production of larger quantities of the products of the reaction in the same period of time. Concentration. Concentration means the amount of a substance in unit volume.
The effect of increased concentration upon the speed of reaction does not seem to be difficult to understand. Naturally, the more molecules of a reacting substance are in a given volume, the greater will be the number of chances for these molecules to react with the molecules of another substance in the same space. In other words, we may say: for the reaction to take place, an A molecule must first meet a В molecule, the chances of their meeting being proportional to the concentration of each.
Catalysts. A catalyst is a substance which makes a reaction proceed more quickly or more slowly than wuold happen were the catalyst absent. The presence of a catalyst is not sufficient for the reaction to be started, it is needed for the reaction velocity to be changed. We find some catalysts to be useful, because they retard certain reactions, but most of the catalysts used commercially are valuable because they accelerate reactions that otherwise would be too slow to use.
The use of a catalyst is frequently of conciderable importance in the manufacturing industries.becsuse it allows a greater quantity of the products of a reaction to be manufactured in a period of time.
Ex. 9. Find Russian equivalent to the following English words:
influence а) содержание
to be affected by б) приводить к чему-либо
content в) влиять
velocity г) объем
result in д) протекать
amount е) замедлять
volume ж) на ... влияет
proceed з) ценный
retard и) количество
valuable к) скорость
Ex. 10. Say whether these statements are true or fals. Begin your answers with
expressions:
You are right. You are not right.
Just so. You are wrong.
I agree with you. It's not correct.
There are no factors which can influance the rate of the reactions,
The factors that influence the rate of the reaction are temperature, concentra tion and catalysts.
The rate of the reaction increases two or four times for a rise of 10° in tern perature.
While rising the temperature the molecules of the substance meet more sel dom.
The more molecules of a reacting substance are in a given volume, the less
will be number of their interactions.
Catalyst is a substance which makes a reaction proceed more quickly.
The presence of catalyst is not sufficient for the reaction to start.
Most of he catalysts used commercially are valuable because they retard re actions.
Ex. 11. Answer the questions.
What factors influence the rate of reaction?
How does the speed of reaction increase for a rise of 10° in temperature?
Why does temperature increase the reaction rate?
What is concentration?
Why does concentration increase the reaction rate?
What is a catalyst?
Can catalyst start the reaction?
What catalysts are more important commercially, which retard or which ac celerate the reaction?
Ex. 12. Describe the principle of action of each factor, which influence the reaction rate.