Yellow Phosphorus. Phosphorus may occur in three allotropic forms: yellow, violet, and black. However, the two most common forms arc yellow and red. There can be traccd a difference of opinion as to whether the red form is a separate allotropic modification. One of the latest theories is that red phosphorus might be phosphorus only partially changed from the yellow to the violet form.
The phosphorus obtained by the reduction of phosphorus is always the yellow variety. This is "regular" phosphorus and the other allotropic forms can be prepared from it.
Phosphorus is able to combine readily with oxygen and ignite in the air at 30 degrees.
Phosphorus is very soluble in carbon disulphide.
Be very careful with the phosphorus solution, as it is highly inflammable. Dispose of it immediately after experimenting cither by burning it or washing it down the drum with large quantities of water.
Red phosphorus is so unlike yellow phosphorus, that it is difficult to realize that both forms arc the same clement. The red type is an amorphous powder. It will not ignite spontaneously. It will not dissolve in carbon disulphidc. It will not glow in the dark. It has no odour and is not poisonous. It ignites only when it is heated to about 240 degrees.
Red phosphorus can be prepared by heating yellow phosphorus in the absence of air. The action may be catalyzed by a trace of iodine.
Violet phosphorus can be prepared by dissolving phosphorus in molten lead and then allowing it to separate by crystallization.
Black phosphorus could be made by subjecting yellow or red phosphorus to 4,000 atmospheres of pressure at a high temperature.
The yellow phosphorus can be prepared from any other form by distillation. When they arc heated strongly enough, all forms of phosphorus vaporize and this vapour always condenses to form the yellow variety.
Remember — phosphorus is like a pretty girl: always interesting, but sometimes dangetvusl
Упр. 4. Что нового вам >далось узнать из текста 11 В по сравнению с текстом 11 А?
Упр. 5. Текст имеет подзаголовки. Выделите основную мысль каждого отрывка, имеющего подзаголовок.
Упр. б. Скажите, что говорится в тексте:
1) об аллотропных формах фосфора; 2) о фосфоре, полученном методом восстановления; 3) о том, что представляет собой красный фосфор; 4) о способе получения черного фосфора; 5) о способе получения желтого фосфора.
Упр. 7. Найдите в тексте предложения, касающиеся соблюдения осторожности при работе с фосфором и переведите их на русский язык.
Scction III
Ex. 1. Think of the situations when the polite ways of expressing request may be used.
| Example: |
I (you, he, she, we, they) should (would) like to; I'd like to; Could you...
I should like to read this book, I know it is very interesting, could you give it to me for some days?
Ex. 2. Translate the sentences into English, using expressions from exercise 1.
1. He могли бы вы сказать мне, какие из этих статей стоит читать? 2. Ты не мог бы помочь мне перевести это предложение? 3. Я хотел бы научиться читать химическую литературу без словаря. 4. Не могли бы
вы показать мне, где лаборатория аналитической химии? 5. Я хотел бы работать в этой лаборатории. 6. Ему хотелось бы прослушать весь курс лекций профессора N, но ему надо уезжать. 7. Она хотела бы заниматься в нашей группе. 8. Нам хотслось бы закончить работу поскорее. 9. Ты не мог бы пойти со мной? 10. Не могли бы вы встретиться с вашим другом и попросить у него последний номер журнала?
Ex. 3. Make up sentences or short stories with the following words:
1) be, interesting, phosphorus, always, scientist, it, peculiar, phos- phorcsccncc, because, possess, property; 2) phosphorus, substancc, be, poisonous, dangerous, careful, handle, must, we; 3) allotropic, three, occur, form, phosphorus, red, yellow, common, be; 4) belong, substancc, phosphorus, category, inflammable
Ex. 4. Give detailed answers to the following questions:
1. Why did phosphorus interest alchemists? 2. What is the history of phosphorus? 3. What is to be known when you work with phosphorus? 4. Describe modifications of phosphorus. 5. What arc the properties of phosphorus?
Ex. 5. Discuss the following topics:
1. The Discovery of Phosphorus.
2. The Phosphorus is a Dangerous Substancc.
3. The Modifications of Phosphorus.
DO YOU KNOW THAT...
One of the first known applications of phosphorus was the production of matchcs. At present phosphorus plays its most important part in agriculture. Phosphatic fertilizers arc widely used in modem agriculture. The prcscncc of phosphates in the soil is ncccssary for plant growth.