Notes on the Text

1. to observe the following rules—соблюдать следующие правила

2. vessel ['vesl]—сосуд

3. handle ['hændl]—обращаться

4. pay ... attention to—обращать ... внимание на

5. precaution has to be taken — следует заботиться

6 . yield [ji:ld]—выход вещества

7. proper order—надлежащий порядок

2. Answer the following questions.

1. In what way must glass things be handled. 2. What must special attention be paid to? 3. Where must bottles containing inflammable or explosive substances be placed? 4. What is necessary to while making experiments? 5. What must you do after finishing work?

2. What rules would you add to the given ones.

2. Complete the following sentences using modal verbs:

1. Chemicals … be used carefully in the laboratory. 2. You … stay out of the laboratory if your teacher is not there. 3. You … obey the laboratory rules when working there. 4. If you … to smell any chemical, fill your lungs with air first, then sniff carefully. 5. As you … see, many of the chemicals … be dangerous. 6. All chemicals … to be treated with care. 7. Ethanol and water … look alike. 8. What we … to remember is that a substance … be recognized by its properties.

2. Read the text and describe the process with the help of the picture. Distillation

Distillation may be carried out simply in a retort or in a distilling flask connected through a condenser to a receiver, often cooled by means of a freezing mixture in an ice bowl. In the Liebig condenser the vapour condenses in a long tube which is surrounded by a water jacket in which the cold water circulates. The stream of cold water flows in at the bottom or cool end of the condenser and out at the top or hot end, so that the coolest part of the tube meets the coldest water, and as the water reaches the hottest part of the condenser it is less cool. By this application of the counter-current principle a uniform temperature-drop along the condenser is ensured, and hence as efficient cooling as possible is provided.

Fig.1 Distillation

/—thermometer; 2—condenser; 3—receiver; 4—distillate, 5—to drain (сток); 6—from faucet (водопроводный кран); 7—wire screen; 8—glass or por­celain boiling chips; 9—residue

2. Read the text and tell about obtaining hydrogen using the picture. Kipp's Apparatus Used for Obtaining Hydrogen

In order to obtain hydrogen Kipp gas generator (Kipp's apparatus) may be used. The upper spherical funnel contains the solution of hydrochloric acid. Iron or zinc is placed in the middle bulb of the generator. When the tap is turned on the acid flows down from the funnel and interacts with the metal. When the tap is turned off the hydrogen formed displaces the acid into the lower part of the gas generator from which the acid passes up the inner tube into the spherical funnel. Hydrogen comes out through the outlet.

F ig. 2. Kipp Gas Generator

/ — hydrochloric acid; 2 — upper spherical funnel; 3—tap; 4—gas outlet (выход газа); 5 — hydrogen; 6 — zink or iron; 7 — lower part; 8 — inner tube; 9 — middle bulb;