Перекись водорода

HYDROGEN PEROXIDE

Теоретическая часть

Данный лексический материал предназначен для того, чтобы студенты овладели общими специальными терминами, словосочетаниями и могли употреблять их в речи при обсуждении специализированных текстов.

Задания

Задание 1. Выучите следующие слова и словосочетания:

1. twice as much — вдвое больше

2. strangely enough — как ни странно

3. acid – кислота

4. hydrogen peroxide – перекись водорода

5. sulphuric acid – серная кислота

6. to remove – удалять, убирать

7. soluble – растворимый

8. insoluble barium salts – нерастворимые соли бария

9. to obtain (= to get) – получать

10. dilute solution – разбавленный раствор

11. to decompose – распадаться

12. under diminished pressure – при пониженном давлении

13. fractional distillation – фракционная перегонка

14. compound – соединение

15. to resemble – напоминать, иметь сходство

16. oxidizing agent – окислитель

17. explosive – взрывчатый

18. reducing agent- восстановитель

19. potassium permanganate – перманганат калия

20. bubble - пузырек

Задание 2. Прочитайте и переведите текст:

HYDROGEN PEROXIDE

Preparation. Hydrogen peroxide may be prepared by the action of an acid on a metal peroxide. Usually, barium peroxide and sulphu­ric acid are employed for this. Barium sulphate is very slightly soluble, so it is easily separated by filtration.

BaO₂ + H₂SO₄-= BaSO₄ + H A

Soluble barium salts are poisonous, their presence is unde­sirable, therefore care is taken to remove them.

If the insoluble barium salts are removed by filtration we obtain a dilute solution of hydrogen peroxide in water. This solution must be made concentrated. If we attempted to concentrate the solution by boiling or distilling at ordinary pressure, the hydrogen peroxide would be decomposed by heat. Consequently, the concentration must be made by distillation under diminished pressure. Un­der a pressure of 26 mm the mixture begins to boil at a temperature of about 27°, the first portion of the distillate is pure water. As the process continues the temperature rises gradually until at 69° all the hydrogen peroxide is distilled. By taking the first portion of the distillate and repeating the process, which is called fractional distillation nearly pure hydrogen peroxide is obtained.

Properties. There exist a number of peroxy compounds, hydro­gen peroxide is the simplest. It contains twice as much¹ oxygen for the same weight of hydrogen as the simple oxide, water. It is an exceedingly interesting compound, in many ways resembling ozone. Since it readily decomposes, yielding oxygen, hydrogen peroxide is an active oxidizing agent. When the decomposition begins the heat liberated hastens the decomposition and the reaction often becomes explosive.

Hydrogen peroxide acts not only as a vigorous oxidizing agent but strangely enough² it also acts as a reducing agent. When hydrogen per­oxide is added to an acidified solution of potassium permanga­nate, bubbles of gas are evolved and the deep purple colour disappears, leaving a colourless solution. The escaping gas is oxygen and the loss of colour is due to the fact that colourless compounds are produced when oxygen is removed from potassium permanganate.

Задание 3. Ответьте на следующие вопросы:

1. In what way can hydrogen peroxide be prepared? 2. Why is barium sulphate easily separated by filtration? 3. Why should soluble barium salts be removed? 4. What are the properties of hydrogen per­oxide? 5. What is the loss of colour due to?

Задание 4. Подчеркните отрицательные суффиксы и префиксы в данных словах, переведите эти слова на русский язык:

undesirable, insoluble, disappear, colourless, until, useless, de­composition

Задание 5. Сгруппируйте синонимы, переведите их на русский язык:

to employ, easily, since, very, to use, as, to give, readily, exceed­ingly, to yield

Задание 6 . Сгруппируйте антонимы, переведите их на русский язык:

slightly, undesirable, simple, combine, desirable, complex, in­soluble, decompose, readily, soluble

Практическое занятие 13