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10. Read about hydrogen and characterize this element briefly. Hydrogen

This substance occurring on the earth and in the sun and stars is the first element of the Periodic Table. Under normal conditions it is a colourless, odourless, tasteless gas. Hydrogen burning in the air must form water in a combination with oxygen. As water hydrogen is everywhere. This element, forming water, is a part of all acids and hydrocarbons. It is also a comprising part of vegetable and animal matter. We can get hydrogen by the electrolysis of water, the steam-iron process, the steam-water gas process.

Notes to the text:

condition – условие

hydrocarbon – углеводород

occur - встречаться, попадаться

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

1. Steel containing some metallic element other than iron and carbon is generally known as "special steel". 2. Mercury may be purified by washing it with dilute nitric acid. 3. They were using this substance in their experiment sev­eral times. 4. While examining the properties of this metal pay attention to its melting point. 5. Upon being heated he oxide changes into the red modification. 6. Being lower than hydrogen in the activity, mercury does not dis­place hydrogen from solutions of the acids.

12. Open the brackets choosing the correct form of the Participles:

1. The investigation (followed/following) by many experiments was of great importance. 2. The work (doing/done) by these researchers resulted to many new discoveries. 3. The nuclei (formed/forming) in this reaction are unstable. 4 The man (speaking/spoken) was the first who discover this phenomenon. 5. When (asking/asked) about this work/ he couldn’t answer anything. 6. Carbon (uncombined/uncombining) is a solid. 7. The man (experimented/experimenting) in that lab is our analyst. 8. The substance (experimented/experimenting) upon is an oxide.

13. Fill in the gaps with the verbs given below. Transform them into the appropriate form.

1. The woman …a new phenomenon is their lecturer. 2. …this paragraph you should take notes. 3. Give this sample to the analyst … at the bench. 4. … a good specialist, our teacher can explain to us difficult problems. 5. … many books in organics my friend must know much about organic substances. 6. … a new phenomenon, specialists can put down new data.

to observe, to be, to have, to explain, to read, to experiment, to analyse

14. Read and translate the text. Write out the words which possibly could help you to characterize any other gas. Chlorine

Chlorine is an element with atomic number 17, atomic weight 35.5 (thirty-five point five). It is a gas at ordinary temperatures and is never found free in nature. It is found in nature only combined with other elements. At normal temperatures, chlorine is a diatomic gas (CL2), greenish-yellow in colour and about 2 ½ (two and a half) times as heavy as air. It liquefies at atmospheric pressure at-34.1 C0 (minus thirty-four point one degrees Centigrade) to a yellowish liquid approximately 1 ½ (one and a half) times as heavy as water. The liquid freezes at-100.98C0 (minus one hundred point nine eight degrees Centigrade).

Chlorine is soluble in water and indirectly exerts bleaching and bactericidal action by reacting with water to form hypochlorous acid.

C l2 + H2O HCl + HCLO HCL+ (O).

The hypochlorous acid is unstable. It gives up oxygen to form more HCl. The oxygen attacks and destroys bacteria. It also oxidizes coloured organic substances, forming colourless or less-coloured components.

Chlorine is one of the most active elements. It ranks in reactivity about with oxygen. Chlorine combines directly and readily with hydrogen and most non-metals except nitrogen, carbon and oxygen. It also unites with all the familiar metals except gold and platinum.

Participating in a number of important organic reactions, in some cases chlorine appears in the final product, as in insecticides (DDT) or in the plastic polyvinil chloride.

Chlorine is generally produced by electrolysis of water solutions of sodium chloride in electrolytic calls. When sodium chloride or potassium chloride solutions are subjected to electrolysis, there are there products: caustic soda or caustic potash, chlorine and hydrogen. If fused sodium chlorine is used, there are two products: chlorine and metallic sodium.

Notes to the text:

ordinary – обычный

to liquefy – переходить в жидкое состояние

approximately – приблизительно

soluble – растворимый

to exert – оказывать

hypochloorous acid – хлорноватистая кислота

unstable – неустойчивый

to oxidize – окислять, оксидировать

caustic potach – едкий калий

fused = molten – расплавленный

ranks in reactivity about with – по своей реактивности почти не уступает кислороду

insecticide – инсектицид

polyvinil chloride – поливинилхлорид

sodium chloride – поваренная соль, хлористый натрий

caustic soda – едкий натрий

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