3 Part One. The Predicate

Section II
Mashq 1. Quyidagi xalqaro so’zlar nimani anglatadi?:

fundamental, balance, operation, utilize, limitation, intuitive, extreme, delicate, calibration, specialize, actually, visualize, ordinary

Mashq 2. Quyidagi so'zlarning ma'nosini eslaysizmi tekshiring; yo'q bo'lsa, lug'atga qarang:

tool, capability, realize, take for granted, precise, ratio, yield, tend, teeter-totter, pendulum, upright, axle

Text 34 В

Matnni o’qing (o’qish vaqti — 2 daqiqaы).

Fundamentals of the Analytical Balance
Of great importance in the laboratory is the analytical balance, one of the most common laboratory tools. Its usefulness increases when the chemist understands its operation well enough to utilize the full capabilities and to realize the limitations of the balance.

Some chemistry students do not become proficient in the use of the balance, understandably, they are concerned with so many other and complex instruments and problems. The balance is taken for granted. It may be that, because balances have been used for so many centuries, intuitive knowledge about them is assumed. At the other extreme are those who know there is something precise and presumably delicatc about a balance, and so they avoid using one if possible. This is unfortunate because mass, along with length and time, is a fundamental measurement.

An example is the use o f the balance to prepare standards for the calibration of more specialized instruments. Another important thing about a balancc is its high ratio o f capacity to sensitivity. Few measurements will yield as many significant figures as weighing on ananalytical balancc. Results to six significant and cxact figures are ordinary.

Those who have learned about balances by an intuitive process tend to think of them as tcetcr-tottcrs. Actually a balancc is a compound pendulum with complications. The essentials of the operation can be understood easily, however, by visualizing an upright wheel free to tum on a fixed axle...

Mashq 3. Matnning asosiy tarkibini bir nechta jumlalarda ko’rsating.

Mashq 4. Matndagi qaysi so'z "mohir " degan ma'noni anglatadi?

Mashq 5. Matnda quyidagi savollarga javob toping:

1. When does analytical balancc become a useful tool in the laboratory? 2. What is the attitude of students to the use of analytical balancc? 3. What measurements are regarded as fundamental? 4. What is the characteristic feature of analytical balancc? 5. What is the design of the analytical balancc?

Mashq 6. Quyidagi jumlalarni to'ldiring:

1. Analytical balancc is... 2. Chemistry students are concerned with...

3. Some students avoid using a balancc because... 4. The balancc can be used to prepare standards for... 5. Usually, a balancc is thought to be...
Section III
Ex. 1. Make up short dialogues according to the example.

Example: — Can 1 help you?

— Yes. I’d like some information about foreign journals on

chemistiy in this library.

— What field of chemistry are you interested in?

— Nature compounds.

— Let’s use the computer, we’ll find all the information you need.
Ex. 2. Respond to the following statemets:

1. Statistical methods are used not only for the design o f experimentation. 2. To my mind, intuition is not important for chemists.

3 .I don’t think the balancc is the most essential tool in a chemical laboratory, there are many others.
Ex. 3. Give detailed answers to the questions.

1. What methods are used in analytical chemistry? 2. What must students be able to do in a laboratory? 3. What aspects must be taken into account in planning experiments?

Ex. 4. Discuss the following topics:

1. Interpretation of Experimental Results.

2. Designs of Modem Analytical Balances.

3. How to Avoid Errors in Experimentation.

4. How to Estimate Experimental Errors.