When I used to take chemistry classes, the teacher would tell us before doing experiments:
1. All experiments must be carried out in accordance with the operating regulations; they must be prepared in the preparation room to ensure that the experiments are correct before they can be carried out in the classroom or laboratory.
2． When doing toxic and flammability experiments, be sure to open doors and windows to allow air circulation.
3. In experiments involving flammable gases, do not mix air or oxidants before igniting or heating.
4． It is better to use less medication than too much. Do not use unidentified and unlabeled reagents. Use them as they are prepared and do not leave them for a long time.
5. If you haven't done any experiments before, you should ask a competent person for advice or find out the information before doing them, and don't do it rashly.
6． For experiments with many steps, the order of operations should be memorized, and you should not just follow each step step by step.
7. The laboratory must have certain safety facilities.
8． Be familiar with first aid methods and handling measures for laboratory accidents.
As long as we understand the causes of various chemical experiment accidents, follow operating procedures, and perform operations carefully, we can avoid various accidents and achieve safe experiments.
1. Can be heated directly
(1) Test tube
Main uses: ① Used as a reaction vessel for a small amount of reagents under normal temperature or heating conditions.
②Collect a small amount of gas and check the purity of the gas.
③Contain a small amount of medicine.
Instructions for use and precautions:
① It can be heated directly and clamped 1/3 away from the mouth of the test tube with a test tube clamp.
②The specifications of test tubes vary from large to small. The liquid contained in the test tube should not exceed 1/2 of the volume when not heated, and should not exceed 1/3 when heated.
③ There should be no water droplets on the outer wall before heating; there should be no sudden cooling after heating to prevent the test tube from breaking.
④When heating, the mouth of the test tube should not be facing anyone. When heating a solid, the test tube should be placed horizontally with the mouth of the tube slightly tilted downwards.
⑤ Do not use test tubes to heat and melt strong alkaline substances such as NaOH.
(2) Evaporating dish
Main uses: ① Evaporation, concentration and crystallization of solutions.
②Dry solid matter.
How to use and precautions: ①The liquid volume should not exceed 2/3 of the volume.
② Can be heated directly, and cannot be cooled quickly after being heated.
③ Crucible pliers should be used to pick up and place the evaporating dish.
(3) Crucible
Main purpose: used for high-temperature burning of solid materials.
Usage and precautions:
① Place the crucible on the clay triangle on the tripod and heat it directly.
② Use crucible pliers when picking up and placing the crucible.
③After heating, it can be placed in a dryer or on an asbestos net to cool.
④ Crucibles of different materials should be selected according to the different properties of the heated substances.
2. The asbestos net can be heated
(1) Beaker
Main uses: ① Used as a container for dissolving solid substances and diluting liquids.
② Used as a container for reactions of larger amounts of reagents.
③ Used for filtration, dialysis, fountain and other experiments, air tightness inspection, exhaust gas absorption device, water bath heating, etc.
④ A cold, dry beaker can be used to test whether water is produced during gas combustion; a beaker coated with clear lime water can be used to test CO2 gas.
Usage and precautions: ① Commonly used specifications are 50mL, 100mL, 250mL, etc., but no beaker is required to measure the liquid.
② It should be placed on an asbestos net for heating to ensure even heating; when heating, there should be no water droplets on the outer wall of the beaker.
③When heating liquid, do not exceed 2/3 of the volume of the beaker. Generally, 1/2 of the volume of the beaker is appropriate.
④ During the dissolution or dilution process, when stirring with a glass rod, do not touch the bottom or wall of the cup.
(2) Flask
Main uses: ① It can be used as a reaction vessel with a large amount of reagents and liquid participation, and is often used in various gas generating devices.
②Distillation flasks are used to separate liquids that are miscible and have large differences in boiling points.
③The round bottom flask can also be used for fountain experiments.
How to use and precautions: ① It should be placed on an asbestos net and heated to make it heated evenly; when heating, there should be no water droplets on the outer wall of the flask.
②Flat-bottomed flasks cannot be used for heating for a long time.
③ When not heating, if a flat-bottomed flask is used as the reaction vessel, there is no need to fix it with an iron stand.
(3) Erlenmeyer flask
Main uses: ① Can be used as a reactor for neutralization titration.
② Replace test tubes, flasks, etc. as gas generating reactors.
③In distillation experiments, it is used as a liquid receiver to receive fractions.
Usage and precautions: ① During titration, only shake without stirring.
② When heating, an asbestos net needs to be placed.
3. Cannot be heated
(1) Gas collecting bottle (bottle edge frosted)
Main uses: ① Used with frosted glass pieces to collect and Store gas temporarily.
② Used as a reaction vessel for the reaction between substances and gases.
How to use and precautions:
①Do not heat.
② Apply a thin layer of Vaseline to the mouth of the bottle and the ground glass to make it airtight.
③When conducting combustion experiments, sometimes it is necessary to put a small amount of water or fine sand at the bottom of the bottle.
(2) Wide-mouth bottles and narrow-mouth bottles (the inside of the bottle neck is frosted)
Main uses: ① Wide-mouth bottles are used to store solid medicines and can also be used to assemble gas generators ( No heating required).
②Narrow-mouth bottles are used to store liquid medicines.
Usage and precautions:
① Generally cannot be heated.
② Use glass stoppers for acidic drugs, oxidizing drugs, and organic solvents; use rubber stoppers for alkaline reagents.
③ Use brown bottles for items that are easily perishable when exposed to light.
(3) Dropper bottle
Main purpose: used to store a small amount of liquid, which is characterized by easy use
Usage methods and precautions: ① The dropper cannot Place it flat or upside down to prevent liquid from flowing into the glue head.
② Use cork or rubber stopper instead when holding alkaline solution.
③Alkaline reagents cannot be stored for a long time.
2. Measuring instruments
1. Graduating cylinder
Main uses: ① Roughly measure the volume of liquid (the accuracy can reach 0.1mL).
②Measure the volume of solids and gases by measuring the volume of liquids.
Instructions for use and precautions:
① There are specifications such as 10mL, 25mL, 50mL, 100mL, 200mL, 500mL, etc. The larger the size of the graduated cylinder, the lower the accuracy.
②The measuring cylinder does not have a zero mark.
③When measuring liquid, the measuring cylinder must be kept flat, and the line of sight should be level with the lowest point of the concave surface of the liquid in the measuring cylinder.
3. Measuring instrument
(1) Pallet balance
Main purpose: used to roughly weigh the mass of substances, with an accuracy of 0.1g.
How to use and precautions:
①Adjust the "0" point before weighing: move the cursor to zero and adjust the balance of the balance.
②When weighing, put paper on two plates, with items on the left and items on the right. Drugs that are easily deliquescent and corrosive must be weighed in glassware.
③After weighing: Return the weight to the box and return the weight to zero.
(2) Thermometer
Main purpose: used to measure the temperature of liquid or vapor.
Usage methods and precautions: ① A thermometer suitable for the measurement range should be selected according to the measurement temperature. It is strictly prohibited to use it beyond the range.
② When measuring the temperature of a liquid, the thermometer's bubble should be suspended in the liquid and should not touch the bottom or wall of the container.
③In the distillation experiment, the bubble of the thermometer is located slightly below the branch mouth of the distillation flask.
④Do not use the thermometer as a stirring rod.
3. Drying instrument
1. Drying tube
Main purpose: Built-in solid desiccant, used for drying gas or connecting it to the container to prevent material absorption Water vapor or CO2, etc.
How to use and precautions:
① Small cotton balls or glass wool should be placed between the sphere and the thin tube to prevent the pores from being blocked
② The gas enters from the end with a large diameter and flows out from the end with a small diameter
③Before using the drying tube, be sure to check whether the drying tube is open.
IV. Other commonly used chemical instruments
1. Alcohol lamp
Main use: Common heat source in chemical laboratories.
Usage and precautions:
①The amount of alcohol should not exceed 3/4 of the volume, nor be less than 1/4 of the volume.
② It is absolutely prohibited to add alcohol to a burning alcohol lamp to avoid fire.
③When extinguishing, cover it with a lamp cap and do not blow it out with your mouth.
④If you need to obtain a higher temperature, you can use an alcohol blowtorch.
2. Gas scrubbing bottle
Main purpose: used to scrub gas to remove moisture or other gas impurities.
How to use and precautions: When using, pay attention to the flow direction of the gas, which is generally "long in and short out". The amount of liquid reagent added into the bottle should be 1/3 of the volume and should not exceed .
3. Funnel
Main uses:
(1) Ordinary funnel
①Inject liquid into a small-mouth container.
② Used in filtering devices.
③ Used in anti-back suction devices.
(2) Long-neck funnel
①Inject liquid into the reactor.
②Assemble the gas generating device.
(3) Glass rod
Main uses: often used for stirring, drainage, and widely used in experiments such as dissolution, dilution, filtration, evaporation, and preparation of substance concentration solutions.
Usage and precautions: avoid contact with the wall of the container when stirring
I hope this helps, but I forgot to adopt it