The chemical laboratory is an important place for providing chemical experiment conditions and conducting scientific inquiry. There are a lot of instruments in it: iron stand, asbestos net, alcohol lamp, beaker, test tube, gas bottle, rubber stopper, reagent bottle, mortar and other experimental tools. Usually equipped with chemical medicine cabinet, there are commonly used medicine cabinet Chemicals, such as: copper sulfate pentahydrate (CuSO4 · 5H2O, namely bile), sodium hydroxide solution, limestone, hydrochloric acid, etc. People use them to the mysteries of matter and its changes. Before entering the chemical laboratory, you must carefully read the laboratory rules and strictly follow the rules. Because many chemicals are very harmful to the human body, they also cause greater pollution to the environment.
Common equipment
1. Iron stand: used to fix and support various instruments, generally used for experimental operations such as filtration and heating
2. Beaker: â‘ Dissolve solid substances, prepare solutions, and dilute and concentrate the solutions â‘¡ Can also be used as a reaction between larger amounts of substances
3. Measuring cylinder: measuring liquid volume
4. Gas collector: used to collect or store a small amount of gas, and can also be used as a reaction vessel for partial reactions
5. Test tube: â‘ Reaction container for a small amount of reagent â‘¡Can also be used as a container for collecting a small amount of gas
6. Test tube clamp: used to clamp the test tube
7. Glass rod: used for stirring, filtering or transferring liquid
8. Alcohol lamp: used for heating
9. Plastic head dropper: The plastic head dropper is used to absorb and drip a small amount of liquid
10. Dripping bottle: dripping bottle is used to hold liquid medicine
11. Wide-mouth bottle: (the inner wall is brushed) It is often used to hold solid reagents, and can also be used as a gas washing bottle
12. Flasks-round-bottomed flasks and flat-bottomed flasks â‘ Commonly used for reactions between large amounts of liquid
13. Erlenmeyer flask â‘ heating liquid, â‘¡ can also be used to install gas generator and bottle washer â‘¢ can also be used for drip receiving container in titration.
14. Evaporating dishes are usually used to concentrate or evaporate the solution.
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Laboratory rules
(1) Access to medicines
1. Storage of medicines: General solid medicines are placed in wide-mouth bottles, liquid medicines are placed in fine-mouth bottles (a small amount of liquid medicines can be placed in drip bottles), sodium metal is stored in kerosene, and white phosphorus is stored in water
2. General principles of drug access â‘ Dosage: use drugs as required by the experiment. If the dosage is not specified, the minimum amount should be taken. The solid should cover the bottom of the test tube, and the liquid should be 1 ~ 2mL. Reagents taken should not be returned to the original bottle, nor thrown away, nor taken out of the laboratory, they should be placed in another clean designated container. â‘¡ "Three nos": No medicine can be taken by hand, tasted by tongue, or directly sniffed with reagents (if you need to sniff the smell of gas, gently fan the mouth of the bottle with your hand, so that only a very small amount of gas enters the nostril)
3. The use of solid medicines â‘ Powder and small granular medicines: use medicine spoons or V-shaped paper slots â‘¡ block and strip medicines: take with tweezers
4. Use of liquid medicine â‘ Pouring method of liquid reagent: Remove the bottle cap and put it upside down on the table (to prevent the medicine from being contaminated). The label should be in the palm of your hand, (to prevent the residual liquid from flowing down and corroding the label). Pick up the reagent bottle, place the bottle close to the edge of the test tube, and slowly inject the reagent. After pouring, close the bottle cap, the label outward, and put it back. â‘¡Dropping method of liquid reagent: use of dropper: a. First expel the air in the dropper, and then draw the reagent b. When dropping the reagent, the dropper should be kept vertically suspended above the container mouth. Drop c , Always keep the rubber nipple on top to avoid being corroded by the reagent d. After the dropper is used, immediately wash it with water (except the dropper on the dropper) e. The dropper must not extend into the container or the wall when in use Contact, otherwise it will cause reagent contamination
(B) Connect the instrument device and the device air tightness check device air tightness check
First immerse one end of the catheter into the water, close to the outer wall of the container with your hand, and stop for a moment. If bubbles emerge from the mouth of the catheter, release your palm, there will be a water column rise at the mouth of the catheter, stop for a moment, and the water column does not fall back. Airtight.
(3) Heating of the substance
1. When heating the solid, the mouth of the test tube should be slightly inclined. When the test tube is heated, it should be heated evenly and then concentrated.
2. When heating the liquid, the volume of the liquid does not exceed 1/3 of the volume of the test tube. When heating, the test tube is about 45 ° from the table top. When heated, first heat the test tube uniformly, and then heat the middle and lower parts of the liquid in the test tube, and Move the test tube up and down from time to time. In order to avoid hurting people, do not point the test tube to yourself or others when heating.
(4) Filter
1. "One sticker, two low, three lean" "One sticker": the filter paper is close to the inner wall of the funnel
2. "Two Low": (1) The edge of the filter paper is lower than the funnel opening (2) The liquid level in the funnel is lower than the edge of the filter paper
3. "Three leans": (1) The lower end of the funnel is close to the inner wall of the beaker. (2) When the glass rod is used for drainage, the lower end of the glass rod is lightly leaning against the side of the three-layer filter paper. After the mouth is filtered close to the middle of the glass rod, the possible causes of the filtrate are still turbid: â‘ the beaker receiving the filtrate is not clean â‘¡ the liquid level is higher than the edge of the filter paper when the liquid is poured â‘¢ the filter paper is damaged
(5) Evaporation
1. During the heating process, stir continuously with a glass rod (function: accelerate evaporation, prevent droplets from splashing due to excessive local temperature)
2. Stop heating when the liquid is close to evaporation to dryness (or more solids appear), and use the residual heat to evaporate the remaining moisture to avoid the solids splashing out due to heat.
3. The hot evaporating dish should be taken with crucible tongs. If the hot evaporating dish needs to be placed on the experimental table immediately, it should be lined with asbestos mesh.
(6) Instrument washing
1. Waste residue and waste liquid are poured into the waste tank, and useful substances are poured into the designated container
2. The standard for washing glass equipment: the water attached to the glass equipment will neither gather into water droplets nor flow down.
3. Grease is attached to the glass instrument: first wash with hot soda ash (Na2CO3) solution or washing powder, then rinse with water.
4. The alkali, alkaline oxides and carbonates insoluble in water are attached to the glass instrument: firstly dissolve with dilute hydrochloric acid, then rinse with water.
5. After the instrument is cleaned, it should not be placed randomly. After the test tube is cleaned, it should be inserted upside down on the test tube rack to dry. [1]
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