The water problem

Text C

1. Pay attention to the following words and word combinations:

сonsumption – потребление

annually – ежегодно

vessel – сосуд

to satisfy the demands – удовлетворять потребности

fuel – топливо

vary – изменяться

2. Read the text and be ready to say if the following statements are true or false. Use the following phrases:

I think it’s right.

It seems to be wrong.

I can’t agree with it.

As far as I know …

To my mind

On the contrary

1. Natural forms of water are always pure.

2. Consumption of water increases greatly.

3. There isn´t any water problem nowadays.

4. Sea water contains many solids.

5. Distillation of sea water gives pure water. This operation demands little fuel.

6. Water purification by using the Sun as the source of heat is economically proved.

Water is the most common and the most useful of all liquids. It was long known that there is no life without water. Man can live without clothes, without shelter and for some time without food. But he soon perishes without water. All his food contains water, from about 60 % in lean meat to 95 % in watery fruit. His body is about 70 % of water. The air surrounding him contains enormous quantities of water in the form of vapour. The surface of the earth is 70 % water to an average depth of over 4 kilometers. And yet man often does not have enough water.

Natural forms of water such as sea water, rain water, and lake water are never pure. Consumption of water increases annually, millions of tons are used each day in industry. It is necessary 100 litres of water to produce one kilogram of paper; 600 litres to produce one kilogram of woolen cloth; 3500 litres for producing one ton of dry cements and 20000 litres in order to produce one ton of steel. It was established that the needs in water are greatest in India, Indonesia, Nigeria, Brazil, Pakistan, Korea, China and Philadelphia. The total amount of water in existence is about 326 million cubic miles. Every man gets along with less than one per cent of the world’s water. But the total population of the world is growing at a rate of 1.7 % annually. So man began treating raw water, filtrating and chlorinating it. He has devised modern methods of collecting, pumping, storing and distributing water. There are the grand enterprises of taming the rivers, of harnessing their strength to produce power for man's use, preventing floods and using the water for increasing the harvest of the land and providing food for the growing family of man. Perhaps a practical way will be found of making the rain fall where it is most needed. And yet the human suffering and economic loss resulting from inadequate water supplies are so great that bold measures are required. Many diseases are associated with lack of clean water and contaminated water and unsafe water supplies. World water supply is the major concern now.

The solution of this problem will be using sea water, because seas cover about 70 percent of Earth’s surface. Sea water varies in composition, it contains many solids dissolved in water. Sodium chloride, common salt, is the most abundant of the solids present. We can easily understand that distillation of sea water will give pure water and leave the solids in the distillation vessel which can be also used. The difficulty is to carry out this operation economically.

To satisfy the great demands of industry, much fuel will be needed for making this distillation. However, using the Sun as the source of heat, sea water has been successfully purified in some countries in recent years.

3. Make up the plan to the text.

4. Give a brief summary of the text.

Text D

1. Read the text and choose the most suitable title out of the given ones:

a) Distilled water.

b) Water transformations.

c) Purification of water.

Water is the greatest chemist in the world. No natural process takes place without it. Chemists could hardly do anything in their laboratories without water. It is impossible to study the properties of substances or their transformations, to prepare new compounds without water. Water is one of the best solvents. It is known that many substances must be dissolved before they can enter some reactions. Not only does water react with many substances, but many chemical reactions may be influenced by it.

For many processes it is desirable that water should be pure. The choice of the process, which is to be used for purification of water, depends on the application of water and on the impurities which it may contain. For instance, water for washing should not contain substances that react with soap. When water is to be used for drinking it is necessary that the microbes should be killed. To achieve this, water which is to be purified, is thoroughly filtered.

Another way to purify water is to boil it.

None of these methods is used for producing pure water in the chemical sense, since most of soluble salts are not affected by the treatment. Here we shall have to remember the fact that water is easily changed into steam while most of the dissolved substances are not volatile. By condensing the steam we shall be able to remove all the impurities except volatile ones. This process is referred to as distillation. Distilled water is widely used both in the laboratory and in industry.

Water used for steam boilers should be free from substances which cause corrosion and scale formation.

2. Write out:

а) key words and terms;

b) the sentences expressing the main idea of each paragraph.

Unit 3

GRAMMAR: Some, any, no. Passive Voice.

1. a) Translate the followingsentences, paying attention to the pronoun some, any, no.

1. He put some solid into the flask and then added some water.

2. There is something in the flask. Is there anything in the flask?

3. Did he put any substance to the flask?

4. No solid is seen in the test-tube.

5. There is no solid in this retort but solution possesses some colour.

6. Any student can make this simple experiment and analyze the solution in question.

7. We have just read some facts about atoms.

8. The substance no longer remains unchanged.

9. Some substances occur in the form of large crystals.

10.There were no physical changes in both cases.

11. Any body when heated to a sufficient high temperature becomes a source of light.

12. They could not get any papers about commercial application of hydrogen.

13. There is no answer to this question.

14. I noticed some mistakes in your translation.

15. I do not notice any mistakes in your translation.

b) Translate the following sentences into Russian, paying attention to the Passive Voice of the verbs.

1. The first theoretical chemistry was founded by Greek scientists.

2. Modern chemistry was begun by Robert Boyle.

3. The law of conversion of substance was discovered by M. Lomonosov in 1748.

4. Regularities in the properties of the elements have been already discovered.

5. The structural chemistry of organic chemistry had been introduced by that time.

6. The research on atomic theory is carried out in our lab.

7. This question will be answered at once.

8. Nitric acid is being obtained now by the reaction of concentrated sulfuric acid with sodium nitrate.

2. Put the words in the correct order to form sentences.

1. Lavoisier, basis the, process, of, was, by, the, formulated, of, combustion.

2. was, liquid, evaporate, not, to, the, allowed.

3. relativity, to, many, of, Einstein’s, referred, researchers, theory, is, by.

4. gas, reaction, by, is, the, rate, of, the, temperature, influenced.

5. compound, not, this, affected, by, insoluble, has, be, acids.

3. Read the text and translate it using a dictionary.

Text A

Дата добавления: 2014-10-17