A catalyst is a substancc that alters the speed of a chcmical reaction without itself undergoing any chcmical change, usually only a small quantity of it is required.
Catalysts arc usually specific in action; thus, a catalyst for one reaction is more often than not useless for any other reaction. They are extremely important substances not only in the laboratory but also in chcmical industry and in biological systems. Thus, the manufacture of sulphuric acid, ammonia and margarine involves the application of catalysts, the most of the chcmical reactions that occur in our bodies arc regulated by these substanccs. In biological systems substanccs called enzymes function as catalysts, c. g., specific enzymes arc used to aid the digestion of food in the stomach.
Chemists have discovered the great majority of reactions that proceed without catalysts. But there arc almost innumerable other reactions that cannot be practically effected widiout a catalyst.
The phenomenon in which a relatively small amount of a foreign material, callcd a catalyst, augments the rate of a chcmical reaction is called catalysis.
A catalyst provides the possibility of new elementary processes taking placc, but it is not consumed during the reaction. If wc cannot have it regenerated, there is no catalysis.
Упр. 3. Передайте основное содержание текста в нескольких предложениях.
Упр. 4. Составьте план текста.
Упр. 5. Прочтите предложения и скажите, соответствуют ли он» содержанию текста. Если нет, исправьте их.
1. A catalyst is a substancc that changcs the rate of a chcmical reaction. 2. A catalyst undergoes little changcs in the reaction. 3. Catalysts arc important both in laboratory and in industry. 4. Enzymes arc catalysts for biological systems. 5. No reaction can procccd without a catalyst.
Упр. 6. Найдите в тексте предложения, гае перечислены отличительные свойства катализа как явления, и переведите их на русский язык.
Section III
Ex. 1. Respond to the following statements. Use the expressions: quite so; I'm of the same opinion; really; it is not quite so; you are absolutely wrong.
1. It is sometimes difficult to make the reaction procccd faster.
2. There is a tremendous number of factors affecting the reaction.
3. Catalysts arc important only in chcmical industry. 4. I hear your supervisor has been awarded the State prize for his work. 5. They say you never attend lecturcs in history. 6. Borodin was not only a chcmist
but an outstanding Russian composcr as well. 7. Prof. N has been appointed head of your laboratory, hasn't he?
Ex. 2. Translate the sentences into English.
1. Говорят, вы уже на втором курсе? — Не совсем так, я еще на первом. 2. Наш лектор — замечательный ученый. — Действительно. 3. Катализатор влияет на реакцию, но и сам изменяется. — Вы абсолютно неправы, в конце реакции катализатор должен восстанавливаться в первоначальном виде. 4. Катализаторы могут участвовать и в биологических процессах.—Совершенно верно. 5. Катализаторы более важны в промышленности, чем в лаборатории. — Я того же мнения.
Ex. 3. Make up short dialogues according to the model.
Model: — A statement.
— A question.
— An answer.
| Example: |
— A statement.
— My supervisor has published a new article.
— What is the subject of his investigation?
— Ion-selective electrodes.
— It's a very promising field.
Ex. 4. Give detailed answers to the following questions:
1. What is the rate of a reaction? 2. What chemical factors affcct the coursc of a reaction? 3. What physical factors influence the speed of a reaction? 4. What is catalysis? 5. In what way does the prcscncc of a catalyst affect the reaction rate?
Ex. 5. Discuss the following topics:
1. Some Examples of Slow and Fast Reactions.
2. Factors Influencing the Rate of Reactions.
3. Catalysis.
WHAT IS IT?
A substancc which can increase the rate of a chcmical reaction without itself undergoing permanent chcmical change. -