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Ask 10 questions to the text

1.8 Look at the picture and say what is what? Where can they be used?

Chemical dishes: funnel, flask, plastic glass, gradated cylinder, test tube, automatic pipet, spouts.

Make your investigation. Design a plan for preparing caustic potash solution using all pictures from Ex.1.8

II Text for additional reading

Scientific measurement

In scientific research, data is gathered. In biology laboratories, mathematical data is' also used. To be understood easily and fully everywhere in the world, there must be one system used by scientists. That's why, in such research, the IS (International System of Measurement) standards are used. The metric system is commonly used, in which the meter is the unit of length, the gram is the unit of mass, and the second is the unit of time. Among these, some that are used especially in the biology laboratory are as follows:

Length

The unit of length is the meter. Other units are arranged in relation to the meter. For instance, 1 m=100 cm; centi - means 1/100, so a centimeter is 1/100 meter. That means there are 100 centimeters in 1 meter.

Mass

Mass is the amount of matter in an object. The units of mass are the gram and kilogram. 1kg=1,000 g = 1,000,000 mg.

Volume

Volume is the amount of space an object occupies. Its unit is the liter.

Time

The unit of time is the second. In a minute there are 60 seconds, and one hour is 60 minutes.

Temperature

To measure temperature, there are three familiar scales: Celsius (Q, Fahrenheit (F) and Kelvin (K). The unit of temperature commonly used all over the world is the degree Celsius (C).

Glassware

Besides the microscope, dissection kits, certain chemicals and dyes, and models and posters, the glassware above is commonly used for practical work in the biology laboratory.

Lab safety

The laboratory has the potential to be either a safe place or a dangerous place. The difference depends on your knowledge of and adherence to safe laboratory practices. As a result, it is very important that you read the information provided here. A few basic rules for working safely in

the laboratory include the following:

General rules

1 - Always keep your work area clean.

2 - Wear proper safety clothing.

3 - Wear proper eye protection.

4 - Read all directions for an experiment several times.

5 - Follow the direction exactly as they are written.

6 - Be careful not to spill any material in the lab.

7- Always wash your hands before and after each experiment.

8 - Do not eat or drink in the lab.


Date: 2016-03-03; view: 1167


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