Properties of Mercury

MERCURY IN THE ENVIRONMENT

Read and translate the text

Mercury is known to be a rare element. The element is found in trace amounts throughout the lithosphere (rocks and soil), the hydrosphere, the atmosphere and the biosphere (in tissues of plants and animals).

In the rocks and soil mercury is found to be measured in fractions of one part per million. In the hydrosphere (the seas and fresh waters) it occurs only in parts per billion. In the atmosphere mercury is present both as vapour and in the form of particles. It should be noted, however, that under natural conditions the amount of mercury in the atmosphere is so small that extremely sensitive methods are required for detecting and measuring it.

The situation is somewhat different in the biosphere. Plants and animals tend to concentrate mercury. For example, it has been found some marine algae to contain a con­centration of mercury more than 100 times higher than that in the seawater in which they live.

Mercury today is used on a substantial scale in chemical industries, it being used in the manufacture of paints and paper as well as in agriculture. The world production of mercury has been found to amount to about 10,000 tons per year.

In agriculture mercury in the form of corrosive sublimate (HgCl₂) can be used for disinfecting seeds. The chlorides of mercury are employed in protecting a number of vegetable crops.

Due to such large-scale uses a considerable amount of mercury waste is likely to flow into the air, the soil, the streams, rivers, lakes. One might ask whether all these may present a threat to health.

In order to answer this question it is necessary to exam­ine the forms in which mercury occurs. Liquid mercury itself is not toxic to man, but mercury vapour, however, can be injurious. The soluble inorganic salts of mercury have long been known to be toxic.

So, knowing properties and forms of mercury it is possible to use it.

Mercury being very important, it is useful to continue investigating its properties very closely.

Mercury is unusual in that it is the only metal which is stable in the liquid state at about 20°C. It has a bright silvery luster, shows little tendency to tarnish at ordinary temperature, it being a good conductor of both heat and electricity.

Because of its uniform expansion over a wide range of temperature, it is well adapted to use in thermometers, and due to its high density, low coefficient of expansion, and slight vapour pressure at ordinary temperature it is well suited for using in the liquid type barometer.

Despite having high boiling point, mercury does show a small vapour pressure even at ordinary temperatures.

Being raised to a temperature above its boiling point, mercury vapour readily conducts electricity at the same time emitting radiation, it being rich in ultraviolet rays.

Notes on the Text:

1. one part per million – одна часть на миллион

2. on a substantial scale – в больших масштабах

3. to amount to – составлять; равняться (чему-л.); достигать (чего-л.)

8. Answer the following questions:

1. Where can mercury be found? 2. What methods are required to detect the presence of mercury in the atmosphere? 3. Where is mercury used? 4. In what form is mercury used in agriculture? 5. What is mercury used for in agriculture? 6. Why is mercury considered to be unusual metal? 7. What properties of mercury do you know? 8. Why can mercury be used in thermometers and barometers? 9. When does mer­cury conduct electricity?

9. Retell the text according to the following plan:

1. The occurrence of mercury.

2. Properties of mercury.

3. The use of mercury.

4. The importance of mercury.

10. Translate the following sentences paying attention to the words in bold:

1. By close study they could learn that the vapours of this substance are dangerous. 2. The similarity of mercury to zinc and cadmium is not very close, the metal showing a greater similarity to copper and silver. 3. Close the test tube until the solution cools. 4. The elements of Group II-B and IV-B of the Periodic System closely resemble the elements of Group III and IV respectively. 5. One degree is the one hundredth part of the temperature range between the normal freezing and boiling points of water. 6. The Li content of samples encountered in this laboratory has ranged from 4 to 98%. 7. The amount of water was not enough to carry out this experiment. 8. It should be noted that the increase in temperature amounted to only 20°C.

11. Choose the Russian equivalents from the right column:

due to присутствующий

considerable для того чтобы

somewhat составлять

present отчасти

to be present благодаря

to be due to обычный

in order to значительный

to amount to быть обусловленным

ordinary присутствовать

12. Explain the meaning of the verb "to do" in the following sentences:

1. The old methods of carrying out such experiments shouldbe done away with. 2 He will dohis best to finish his work in time. 3 Among the gases with which mercury does react is hydrogen sulphide. 4 Being lower than hydrogen in the activity series mercury does notdisplace hydrogen from solution but it does react with the oxidizing oxides to form their respective salts. 5 While no exchange takes place between chlo­ride bromate and the corresponding halogen in neutral so­lutions exchange does occur if the solution is acidified. 6 Gold does notcombine with oxygen or with sulphur and does not reactwith any familiar acids. It does, however, combine withchlorine and bromine. 7 Copper does not displace hydrogen from acids, but does react with acidic oxidizing agents. 8They did carry out this work in due time. 9 Despite Its high boiling point, mercury doesshow a small vapour pressure even at ordinary temperature. 10 They always do everything in due time. 11 Doyou knowthat a quite new property of this substance was observed? 12 I'll do my best to study well.

13. Translate the following constructions into Russian:

1. Having examined the substance, they...

2. They having investigated the substance, the analyst

3. His investigating these phenomena resulted in...

4. The scientists having done new discoveries, it was...

5. The examination of this mixture being carried out, they...

14. State the functions of the Infinitives and translate the following sentences into Russian:

2. This substance was purified to investigate its properties carefully. 3. Lead is known to be a bright silvery metal with a pronounced bluish colour. 4. The radiation was first thought to consist of gamma-rays, but the energy relationships were found to disagree with this assumption. 5. They proved soluble lead salts to be poisonous. 6. They have been told to ex­amine all the found precipitates. 7. The laboratory appeared to have been equipped very well. 8. The sediment to be investigated appeared on the bottom of the flask. 9. They are likely to have proved this solvent to be very volatile. 10. They were asked to find out all the constituents of the compound. 11. A series of experiments was conducted to determine the effect of adding this element.

15. Analyze the "ing"-forms and translate the sentences into Russian:

1. Copper being a good electrical conductor, they used it in their experiment. 2. Like all soluble aluminium salts, the sulphate is readily hydrolyzed, yielding both aluminium "hydroxide" and a solution which is acidic. 3. As a result of one reaction decreasing in velocity while the other is increasing, a point presently is reached at which the two reactions are proceeding at the same rate and the products of each reaction are being used up at the same rate at which they are formed. 4. The temperature increased, the heat being evolved. 5. The solution obtained, we could begin carrying out our experiment. 6. Large amounts of hydrogen are used in industry in converting oils into solid fats. 7. Many nuclear reactions result from interacting of nuclei and neutrons. 8. Using only very small quantities of the substances he succeeded in obtaining a considerable amount of information about the chemical properties of the elements. 9. They were using this substance in their experiment several times. 10. Being lower than hydrogen in the activity, mercury does not displace hydrogen from solutions of the acids. 11. His having created this new machine soon became known to everybody. 12. All nitrates decompose upon being heated and hence serve well as dry oxidizing agents.

Дата добавления: 2014-11-07