(1) the use of inflammable, explosive, corrosive and toxic chemicals and electrical equipment should be strictly followed in accordance with the operating procedures. Use electrical equipment should be especially careful, do not use wet hand to open the switch of electric switch. Do not use the leakage instrument in case of electric shock. The electrical appliance should be cut off when used.
(2) no food or smoking is allowed in the laboratory. All chemicals are prohibited. Wash your hands after the experiment.
(3) when using chromic acid lotion, strong acid, concentrated alkali and other reagents that are highly corrosive, do not splash on the skin and clothes. In the experiment, when there is strong acid, poisonous or irritating gas, liquid, etc., should operate in the fume hood. When heated in a test tube, the test tube cannot be used to the person. Do not overlook the container that is heating.
(4) familiar with the location and use of fire fighting equipment. In case of an accident, the corresponding measures should be taken immediately.

Biochemical reagent
Pure water is the most commonly used pure solvent and detergent.
Chemistry experiment in the quality of water has certain requirements, according to the quality of the water can be divided into primary, secondary and tertiary (25 ℃, the electrical conductivity were about 0.1, 1.0 mu mu S ? cm - 1 S, cm - 1, 5.0 mu S, cm - 1). The three levels of water are the most commonly used pure water, often by distillation, ion exchange and other methods.

The washing of glass instruments
Clean glassware should be transparent, its inner wall should be able to be moistened evenly without water beads.
General vessels such as the beaker or reagent bottle, taper bottle can use tap water to wash first, and then rinsed in ordinary washing liquid prepared with washing powder, household cleanser, pollution serious when rinsed in hot liquid detergent or special detergents are available, and then rinse with tap water, with a small amount of deionized water finally rinsed wall 2 ~ 3 times.
Titration tube, volumetric bottle, pipette and so on, because its capacity is accurate, shape is special, should not use brush mechanically to wipe the inside wall. Usually soak the inner wall with special lotion, then rinse with tap water and deionized water.
Special detergent has hydrochloric acid solution, chromic acid lotion and so on. Chromic acid lotion is highly corrosive, highly oxidized and strongly acidic, and should be used carefully. In addition, hydrochloric acid - ethanol solution (1:2) is often used to wash the absorption pond, colorimetric tube and suction tube of colored solution or organic reagent.

The glassware is dry
The clean glass instrument can be inverted to dry.
Or in the electric heating oven at 105 ℃ or so dry.
For can’t use high temperature heating drying capacity with calibration instruments, such as pipette, pipette, volumetric flask, burette, etc., can use a small amount of organic solvents such as acetone or ethanol elution again later, pour out the water mixture, or use a hair dryer to dry hot air is blown dry.

Laboratory heating
There are two ways of direct heating and indirect heating:
When the liquid in the test tube is heated directly, the outer wall of the test tube shall be dried and the upper part of the test tube shall be caught in a test tube. The nozzle should be tilted upward and not to the person, so as to prevent the boiling of the liquid from splatter. The amount of liquid added should be less than 1/3 of the length of the test tube. Heat the upper part of the liquid and then move it up and down to make the tube warm and uniform. The container should be placed on the asbestos network to prevent the container from being unevenly heated and resulting in the failure of the liquid in the container directly heated to the beaker and flask. The volume of liquid in the beaker and flask shall not exceed 1/2 and 1/3 of its capacity respectively. The solution should be stirred properly when heated.


Indirect heating of liquid can achieve uniform heating effect. Often use water bath, oil bath, sand bath etc. If heated liquid heated evenly, and the temperature should not exceed 100 ℃, the water bath heating can be used. When temperatures higher than 100 ℃, can use oil bath or sand bath heating. Oil bath according to different requirements for temperature, can use glycerine bath (140 ℃ ~ 150 ℃), liquid paraffin bath (< 220 ℃) and silicone oil bath (> 250 ℃), etc.

Dissolving
When the solid substance is dissolved, it is usually placed in the beaker, and the appropriate solvent is selected, and the method of heating and stirring is used to dissolve it.