News - The basic operation of the chemical experiments

1. In the laboratory, no matter what drugs, should do the "three no's":

Do not touch drugs; nostrils conspire to the mouth of the container to smell drugs (especially gas) odor; shall not taste the taste of medicines.

2. Remaining drug processing: with leftover medicines do not back into the original bottle, and do not be thrown away, not to come up with the lab, to be placed in a designated container. (Excess white phosphorus back into the original bottle)

3. The use of alcohol lamp

Alcohol lamp between the volume of alcohol in the alcohol lamp 1/4-2/3;

Absolute prohibition add alcohol to the burning alcohol lamp;

The absolute prohibition of alcohol lamp ignited other alcohol lamp;

Alcohol lamp can not blow out through your mouth, use the lamp cap off when not cover the lamp cap (reason: ① prevent alcohol evaporates waste of alcohol; ② alcohol evaporates water left on the wick, the next not ignite or burn is not busy );

The alcoholic fire, extinguished with a wet cloth or sand, and not with irrigated (reason: with irrigated will make the fire spread).

4. To a solid heating tubes, slightly downwardly inclined (to prevent the backflow of the water produced back to the bottom of the tube, causing the cell burst), the Tiega folder away from the nozzle of about 1/3 (or tubes in the upper part), the first preheating of the tube mouth, After the centralized heating.

With a test tube is heated to a liquid, the tubes inclined about a 45 ° angle with the desktop, the amount does not exceed 1/3 of the volume of the liquid, first preheated, after the concentrated heating. Do not spout facing the people.

Instrument: directly heated tubes, evaporation pans combustion spoon

Need to pad plus the asbestos net to heating of the instrument: beaker, conical flask, flasks, etc.

Non-heated instrument: graduated cylinder, set cylinder

5. Drugs access

The experiment did not specify the amount, should take a minimum amount, take 1 mL of ~~ 2mL liquid, solid long as covered with the bottom of the tube. Access to solid: powdered medicine spoon (a flat two get three vertical), massive tweezers (a flat put three slow vertical).

Access to liquid:

① take large amounts, with dumping law, cork upside down, dumping labels to the palm of the hand (to prevent the residual liquid corrosion label), the test tube tilt the bottle next to the nozzle down after the label outward, back in place.

(2) Apply a small amount with a plastic head dropper sent packing in the liquid surface (draw air, dropping, do not reach into the container, should be vertical hanging above the mouth of the container; take liquid dropper Do not lie flat, not inverted; used after cleaning, do not wash drops dropper bottle)

(3) take the quantitative measuring cylinder, plastic head dropper bottom (line of sight with the liquid meniscus at the level, not looking up, looking down reading)

6. The connection of the device

First want to insert one end of the glass tube water Run (1) glass tube with rubber tubing, rubber stoppers connection:

Wet, gently precession.

② entire device connection order: from left to right, bottom-up

7. Washing glassware

① water and test tube brush to wash; ② If the tube wall with oil pollution, with hot soda solution or detergent cleaning; ③ If the tube wall with insoluble metal oxides, alkali carbonate, can be soaked with dilute hydrochloric acid, and then washed with water. The uniform a glass instrument washing clean mark: the instrument inside and outside the walls of the water film, neither clustered into water droplets, not into shares shed.

8. Air tightness of the inspection device

One end of the catheter into the water, put his hands to his test tube outer wall of the conduit opening bubbles produce and release the hand conduit opening the water column to produce good air tightness.

9. Filter

Filtration is separated from the liquid, a method of the insoluble solid.

The instruments used are: iron sets (with hoops), beakers, funnels, glass rod, filter paper.

Its operating points:

⑴ a filter paper close to the funnel wall

⑵ two low liquid level below the filter paper edge, filter paper edge below the funnel edge

⑶ the Three the beaker mouth close to the glass rod central glass rod lower end of the light by the side of the three-layer filter paper, funnel close to the bottom inside of the beaker.

The role of the glass rod: drainage. Filtered again, the filtrate turbidity, then the operation is: two to three times if the filter two or three times and then filtered and the filtrate is still cloudy, possible causes are:

⑴ the liquid level is higher than the edge of the filter paper

⑵ filter paper break

⑶ instrument is not clean

10. Evaporated (evaporating dish amount does not exceed the liquid volume of 2/3)

The instruments used are: iron sets (with hoops), evaporating dish, glass rod, alcohol lamp.

Note: (1) heating applications glass rod stirring constantly, so that the liquid is heated evenly, to prevent liquid splash. ⑵ should stop when the evaporating dish in a large number of solid heating using waste heat the remaining water evaporation. (3) access evaporating dish with crucible tongs, heated evaporating dish on the asbestos-line can not use your hands, not on the bench, so as not to scorch the bench.

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