Chemistry is a great and complex subject. It is a of substances, their properties(пропртииз) and the reactions that change them into other substances
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- 8.On measurements
| 5.6.7.15. 16.17. Our chemical laboratory
This is our chemical laboratory (lab). We have our practical classes on chemistry in the chemical lab. It is a light (lайt) room. It is on the first(фәст) floor (флур). Our lab is a large (лардж) room. There are two benches(бэншс) in it. There are shelves (шэлвес) and racks(ракс) above the benches. On the shelves (шэлвес) you can see some glasswear(ˈɡlasˌwer). You can see funnels(фэнэлс), beaker (бэйкэ) and flasks (фласкс)of different forms on the shelves. There are also bottles (ботлс) with liquids and solids on the shelves. On the benches there are burners(бөрнәрс) , crucibles (крисөбэлс) and scales. There are also test-tube stands and filter-stands there. There is a sink with running water in every chemical lab. On the wall, you can see the Periodic Table. Each student has his or her working place in the lab. The students of our University study chemistry. The first-year students study inorganic(инерганик) chemistry. They have practical classes in a chemical lab, which is equipped (экуипэт) with special apparatus. During practical classes, the students make many interesting experiments. They study the properties of pure (пиё) elements, obtain (əbˈtэн) solutions and mixtures(miksCHərs). Before a reaction, they weigh(уэй) substances, as they have to know the exact amount of substances, which they use in a reaction. During the reaction they observe (əbˈzərv) it and at the end of a reaction they record(рекорд) the yield(еилдт). 8.On measurements Measurements are the basis of all scientific work. There are many different units of measurements depending on what it is we want to measure. There are measurements of length, mass, time, volume, density, and many others. There are three fundamental units: units of mass, length and time. All other units can be expressed as combinations of these basic units; they are called derived units. The fundamental unit of time is one second.The fundamental unit of length is one metre in the metric system and it was one yard in the old British system. The British system was substituted by the metric one in 1971 but the units of it are sometimes in use in everyday life. In all scientific measurements the units of the metric system are used. The metric system. The metric system is a decimal system applied to the measurement of length and mass. The basic unit of length is the metre, and the basic unit of mass is the kilogram. The most common prefixes in the metric system are milli-, centi-, and kilo- which mean one thousandth of, one hundredth of and one thousand times the standard of length or mass. Volume of solids. The volume of a solid is expressed in cubic measure, for example, in cubic centimeters (cc or cm3)or cubic millimeters (mm3). Since 1 cm equals 10 mm, it follows that 1 cm3 equals 1000 mm3 Example: The length, width, and height of a rectangular box are 10.0 cm, 7.0 cm, and 5.0 cm respectively. Compute the volume of the box in (a) cubic centimeters and(b) cubic millimeters. Volume = 10 cm x 7 cm x 5 cm = 350 cm3 Volume = 350 cm3x 1000 mm3/cm3= 350.000 mm3 жүктеу/скачать 22 Kb. Достарыңызбен бөлісу:
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