,e

Fig. 4, a new, simplified technique for catalytic com­bustion of organic materials in oxygen.

The most convenient laboratory method for the ^ tion of hydrogen is based on the reaction of zinc with dr sulphuric acid.

The gas is to be collected over wter (se,e Fig. 3).

Zinc’s rate of reaction can be dfisify controlled by regula - ing the rate with which sulphuric acid is added.

Zn + H₂S0₄ —* H₂ + ZnSO,

The surface of pure zinc placedlinla solution of dj^lutesul- phuric acid (becomes coated with a fiM of hydrogen, the reac- tion pfeee^yery-Ж^ The evolution of gaseous hydrogen cannot be observed.

1. What is the laboratory method for the preparation of hydrogen based on?

2. Where is gas to be collected?

3. How can the zinc’s rate of reaction be controlled?

4. Can the evolution of gaseous hydrogen be observed?

Ex. 26. Read the text using a dictionary and retell it:

A New, Simplified Technique for Catalytic Combustion of Organic Materials in Oxygen

A new technique h^ed for the rapid determination of sulphur halogens and traces of njgtals in organic substances.

^{This done b}i#i®Pj^,^cor^^^usf^{ion in} oxygen. No elabo­

rate equipment is required'

By means of thjs rnethod i^Js possible to convert organic materials into soluble combustion products which then have to be analysed by usual inorganic gravimetric or volumetric methods.

Conical f 1 as к is, ща d e of barosilicate gjass^^ee Fig. 4, p. 72)..., It has an elongated stopper with attached platinum $ire^v S^aUf едадрр1е carrier and a holder of a sample. The sample is to be wrapped and is to be placed in the platinum carrier. Th^ri^ the flask has to be charged with a small Amount of absorbing ^u liquid and with free-flowing oxygen.

Grammar: 1. Modal Verbs (continuation). 2. The use of since.

Text; The Measurements in Chemistry.

Ex. 1. Pronounce the following

between [bi'twirn] -'°^c "'f'l balance ['baebns] calorimeter [,kaeb'nmito] "'thermometer [Ba'momita] ^cylinder ['silmdo] burette [bjuo'ret]

^pipette [pi'pet] volumetric kvolju'metrik] barometer [bo'romito] polarimeter kpoub'rimib] refractometer [,ri:fraek'tomito]

рсЛ '■/ *

sampfe Vsa:mpl] -ЛГ microscope ['maikmskoup] lenses ['lenziz] perniit [рз'тй] ■

naked eye^t'neikid 'ai] qualitative ['kwohteitiv] metric [⁷metrik] ^ <-'^{r r}

millimetre ['mil^mkta] micron ['maikron] kilogram ['kilogram]

LESSON 10

Ex. 2. Read the following word combinations:

quantitative relationship ['kwontiteitiv ri'bjbnjip]

measuring devices ['тедэпд di vaisiz]

graduated cylinder ['graedjueitid 'silinda]

burettes for the measurements [bjua'rets fs Зэ megamsnts]

extremely short [iks’tri:mli 'J"o:t]

unit of mass ['ju:nit av 'maes]

Ex. 3. Read the following words, mind the stresses*

determine [di'to:mm] — determination [di,te:mi'neijM] microscope ['maikroskoup]— microscopic hmaikro'slopik] measure ['теза] — measurement ['тезэтэпП volume ['volju:m]— volumetric bvolju'metnkj

Ex. 4. Read the following fluently:

1. We studied the measurements in chemistry. 2. This is the one type of measurement. 3. The microscope is an instru­ment for making very small objects look larger. 4. The funda­mental unit of the metric system is the metre.

Ex. 5. Fill in the blanks with “to have to”, “to be to”, “must” according to the sense:

1. The experiment . , . take place on Monday, I think everything is ready. 2. They . . . examine this sample under a very powerful microscope as it is very small. 3. I am very tired, I . . . have a rest. 4. Our meeting . . . take place after our last lecture. 5. You . . . work hard if you want to finish this work. 6.1... go to the reading-room as I have no books at home. 7. He . . . wait for two hours as his train has just left. 8. All the students of our Institute . . . carry out a num­ber of experiments in analytical laboratory.

Ex. 6. Fill in the blanks with “can”, “could”, “to be able to”:

1. If you come earlier, I ... help you. 2. This solution , , . be evaporated now. 3. Yesterday he .. . finish his experiment, I think he ... do it today. 4. As he was very busy he. . . attend the lecture.

Ex. 7. Translate the following sentences into Russian:

... i так как, поскольку Note: since _{c тех nopj как; c0} времени

1. Since we know all the properties of the substance, we can use it in our experiment. 2. Many interesting investiga­tions have been done since the foundation of this research la­boratory at our plant. 3. Helium belongs to the same group as argon since it does not combine with other elements. 4. I have not carried out any experiments in the laboratory since

I graduated from the Institute. 5. We couldn’t finish our work since we had no necessary devices. 6. Since the kinetics of the reaction was studied at room temperature, the results were good. 7. This element has been known since the 19th century.

Ex. 8. Translate the following sentences paying attention to the mean­ings of the word “order”:

1. D. I. Mendeleyev arranged the elements in the order of increasing atomic weights. 2. In order to be used in a chemi­cal laboratory natural water must be purified. 3. The order was announced at the meeting. 4. In order to dissolve this sub­stance one must heat it. 5. The students must put everything in order when they finish their work. 6. In order to study the relationship between microstructural and mechanical prop­erties of the gel, it is very important to use pure stable gels.

Ex. 9. Give the Russian equivalents of the following words:

close relationship, exact measurement, quantitative ana­lysis, necessary method, the order of arrangement.