1． Use of pallet balance. There are two ways, one is to put the weighing object first and then add the weight, which is suitable for weighing a substance of unknown mass; the other is to put the weight first and then add the weighing object, which is suitable for weighing Take a substance of a certain mass. When using a pallet balance, pay attention to (1) "zero adjustment and anti-corrosion", that is, adjust the balance of the balance first. Moist or corrosive drugs must be weighed in glassware, and other solid drugs should be placed on each end of the balance. Paper of the same size. (2) "Left objects and right objects" means that when weighing, the object to be weighed is placed on the left disk and the weight is placed on the right disk. (3) "Big first, then small" means that when taking weights, take the one with the larger mass first, and then the one with the smaller mass. (4) "Return to zero and put in the box" means that the weighing is completed. The weight should be moved back to zero and the weight should be returned to the weight box.

2． Grinding of solids

The mortar is an instrument stipulated in the new syllabus. When used to grind solid substances, it cannot be smashed, but can only be crushed or ground finely. When grinding, you should pay attention to the following six points:

(1) Larger pieces of medicine can be crushed with a pestle and then ground.

(2) The medicine contained cannot exceed 1/3 of the mortar volume.

(3) When grinding, the pestle head should be pressed against the mortar body, and the mortar wall and pestle head should be moved in a circular motion slowly and then quickly along the lower part of the mortar. Scrape the stained medicine into the mortar.

(4) The ground medicines should be transferred to pre-prepared containers in a timely manner.

(5) Wash the mortar and pestle after use and dry them.

(6) Flammable and explosive substances cannot be ground. When grinding two substances, they are generally ground separately.

3． Use of measuring cylinder. Three points should be noted: (1) Do not prepare solutions or carry out chemical reactions in the graduated cylinder, and do not heat; (2) When observing the scale, the graduated cylinder should be kept flat and your eyes should look straight; if you measure a specified volume of liquid, determine the liquid according to the scale surface; if the volume of an unknown volume of liquid is determined, the scale is determined by the liquid surface. (3) The natural residual liquid in the measuring cylinder should not be transferred after washing.

4． Dissolution of solid pharmaceutical products. Generally, the solid should be ground finely first, and stirred when dissolving. The glass rod should not hit the wall of the container during stirring to prevent damage to the container.

5. evaporation. Four points should be noted: (1) The liquid added to the evaporating dish should not exceed 2/3 of the volume of the evaporating dish; (2) During the heating process, a glass rod should be used to stir continuously to prevent droplets from splashing due to excessive local temperature; (3) Heating should be stopped before evaporation to dryness, and the remaining heat should be used to evaporate the solvent; (4) When removing the uncooled evaporation dish, it should be placed on an asbestos mesh, not directly on the experimental bench.

6. filter. Pay attention to the "one post", "two low" and "three dependence". "One stick" means that the filter paper is close to the inner wall of the funnel, with no air bubbles left in the middle (press it with your hands and moisten it with water during operation), "two low" means that the edge of the filter paper should be lower than the funnel mouth; the liquid in the funnel It should be lower than the edge of the filter paper. "Three leans" means that the tip of the beaker for pouring liquid should be close to the glass rod; the end of the glass rod should be gently leaned against one side of the three-layer filter paper; and the nozzle at the lower end of the funnel should be close to the inner wall of the beaker. If the filtrate is still turbid, it should be filtered again.

7． Instrument assembly. Pay attention to going from left to right and bottom to top; check the air tightness first, then add medicine.

8． How to check the air tightness of the device.

(1) Air tightness inspection method for devices without long-neck funnel. Put the end of the tube into the water and heat the test tube with your hands (or use an alcohol lamp to heat it) for a while. If bubbles emerge from the water and a water column forms in the tube after the test tube cools, it proves that the airtightness of the device is intact.

(2) Air tightness inspection method for devices with long-neck funnels. First clamp the rubber tube with a water-stop clamp, and then add water to the long-neck funnel so that the liquid level in the long-neck funnel is higher than the liquid level in the test tube. After a period of time, the liquid level in the long-neck funnel does not change, which proves that the device is gas-free. The tightness is intact.

9． To heat the solid in the test tube, preheat it first, and then fix the lamp flame (outer flame) to the place where the solid is placed for heating.

10． Issues that should be paid attention to when dismantling the device after using the drainage method to collect gas: first withdraw the air pipe from the water tank, and then stop heating