Hydrogen peroxide

Text B

1. Match the English words and word combinations in A with their Russian equivalents in B.

compound храниться

dilute acid существенные изменения

high density обладать свойствами

rays соединение

combustion of hydrogen высокая плотность

to shake up лучи

when heated при нагревании

appreciable change разбавленная кислота

to be kept встряхивать

to possess properties горение водорода

2. Read the text trying to understand its main idea.

Hydrogen peroxide is a remarkable compound. It is formed in small quantities in a variety of reactions. For example, it is formed when oxygen is bubbled about the electrode from which hydrogen is being evolved during the electrolysis of dilute acid, and also at the anode during the electrolysis of dilute sulfuric acid by a current of high density. Water confined in a quartz vessel is decomposed by exposure to ultra-violet light rays from a mercury lamp, sunlight, etc., and hydrogen peroxide and hydrogen are formed:

2H₂O = H₂O₂ + H₂

Hydrogen peroxide is produced during the combustion of hydrogen in air. For instance, when a jet of burning hydrogen impinges on the surface of cold water, in which ice is floating, or on ice itself, hydrogen peroxide can be detected in the water; and is formed when moist ether is exposed to sunlight. Like ozone, hydrogen peroxide can be formed at a high temperature by passing a current of moist oxygen through a tube and rapidly chilling the issuing gases. It is often formed when a substance is oxidized in the presence of moisture. For instance, when zinc, copper or lead is shaken up with air and dilute sulfuric acid the reaction symbolized:

Zn + 2H₂O + O₂ = Zn(OH)₂ + H₂O₂ and Zn(OH)₂ + H₂SO₄ = Zn SO₄+ 2H₂O.

Hydrogen peroxide is ordinary made by the action of acids on certain peroxide, such as sodium peroxide or barium peroxide. By treating a cold aqueous solution of sodium peroxide with dilute and cold hydrochloric acid, a solution of hydrogen peroxide mixed with sodium chloride is obtained:

2HCl + Na₂O₂ = 2NaCl + H₂O₂.

This is convenient on account of the ease with which hydrogen peroxide decomposes when heated.

Pure hydrogen peroxide is a viscid liquid. It is colourless when viewed in thick layers. The liquid is odourless. Dilute aqueous solution has a bitter metallic taste. The liquid decomposes rapidly when heated at ordinary atmospheric pressure. It boils at 68-69 °C under about 28 mm pressure. The liquid is soluble in water in all proportions. Pure hydrogen peroxide is stable. Dilute aqueous solutions may be kept for a year with no appreciable change. Alkaline solutions are not kept very well. Pure H₂O₂ is decomposed rapidly if any dust is present. Hydrogen peroxide possesses strong oxidizing properties.

3. Divide the text into some logical parts and entitle them.

4. Translate the following sentences into English using lexical material of the text:

1. В процессе электролиза участвуют разбавленная кислота и ток высокой частоты.

2. Для проведения реакции используется кварцевый сосуд.

3. Поток влажного кислорода пропускают через трубку.

4. Перекись водорода образуется при окислении вещества в присутствии влаги.

5. оксид водорода разлагается при нагревании.

6. Разбавленные водные растворы могут храниться без существенных изменений.

Text C

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

dew – роса

needle – игла

silk – шелк

ivory – слоновая кость

feathers – перья

straw – солома

metallic lustre – металлический блеск

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

It seems to be wrong (right) …

As far as I know …

Far from it. …

If I am not mistaken…

To my mind…

It’s not true to the fact.

1. Hydrogen peroxide doesn´t occur in nature.

2. Hydrogen peroxide appears colourless in thick layers.

3. Pure hydrogen peroxide is not stable.

4. Alkali solutions are kept without any appreciable change.

5. Pure hydrogen peroxide is decomposed in the presence of dust.

6. Hydrogen peroxide doesn´t act as an oxidizing agent.

7. Hydrogen peroxide can be applied in medicine.

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