(l) A test tube is a container that contains a small amount of drugs and makes a small amount of reagents react at room temperature or under heating conditions, and can be used to prepare or collect a small amount of gas.

Precautions for use: ① It can be directly heated and clamped with a test tube at a distance of 1/3 from the test tube mouth. ② The liquid in the test tube shall not exceed 1/2 of the volume of the test tube when it is not heated, and shall not exceed 1/3 when it is heated. (3) It cannot be quenched after heating to prevent bursting. (4) When heating, the nozzle should not deal with anyone; When heating solids, the test tube should be placed horizontally with the nozzle slightly inclined downward.

(2) Beakers are used as reaction containers for preparing solutions and a large number of reagents, and are used at room temperature or when heating.

Precautions for use: ① When heating, put it on an asbestos net to make it heated evenly.

(2) when stirring the dissolved substance with a glass rod, do not touch the cup wall or bottom.

(3) Flasks are used for containers with a large amount of reagents and liquid substances involved in the reaction, and can be divided into round bottom flasks, flat bottom flasks and distillation flasks. They can all be used to assemble gas generating devices. Distillation bottles are used for distillation to separate mutually soluble substances with different boiling points.

Precautions for use: ① Round bottom flask and distillation flask can be used for heating, and should be padded with asbestos net, and can also be used for other hot water baths (such as water bath heating). ② The amount of liquid added should not exceed 1/2 of the flask volume.

(4) The evaporating dish is used to evaporate liquid or concentrate solution.

Precautions for use: ① It can be directly heated, but it cannot be quenched. (2) The volume of liquid should not exceed 2/3 of the volume of the evaporating dish. (3) Take and put the evaporating dish with crucible tongs.

(5) Crucibles are mainly used for high-temperature combustion of solid substances.

Precautions for use: ① Place the crucible on the mud triangle on the tripod and heat it directly. ② Crucible pliers should be used when taking and placing crucibles.

(6) Heating sources commonly used in alcohol lamp chemical experiments.

Precautions for use: ① The wick of alcohol lamp should be flat. ② When alcohol is added, it shall not exceed 2/3 of the volume of alcohol lamp; Alcohol is not less than l/4. It is absolutely forbidden to add alcohol to the burning alcohol lamp to avoid fire. ④ It is absolutely forbidden to light another alcohol lamp with an alcohol lamp. ⑤ After using the alcohol lamp, be sure to cover it with a lamp cap, and don't blow it with your mouth. ⑥ Don't knock over the alcohol lamp. If spilled alcohol burns on the table, immediately cover it with a damp cloth.

2. Instruments for separating substances

(1) Funnels are divided into ordinary funnels, long-necked funnels and separatory funnels. Ordinary funnels are used to filter or transfer liquids to small-mouth containers. The long-necked funnel is used to inject liquid into the gas generating device. The separating funnel is used to separate different liquids with different densities and immiscible with each other, and can also be used to add liquids to the reactor at any time. It is also used for extractive separation.

(2) Gas cylinders are generally assembled with wide-mouth bottles, conical bottles or large test tubes in middle schools. The liquid contained in the washing gas cylinder is used to wash the gas and remove moisture or other gas impurities. Pay attention to the flow direction of gas when using, which is generally "long in and short out".

(3) drying tube The solids contained in the drying tube are used to wash gas and remove moisture or other gas impurities, and a U-shaped tube can also be used.

3. Measuring instruments

(l) The pallet scale is used for weighing with low precision requirements and can be calibrated to 0.1g.. The attached weight is the standard for weighing substances on the balance.

Precautions for use: ① Before weighing, the balance should be placed stably and the line code should be placed at the zero position of the scale. Adjust the left and right balance nuts of the balance to balance the balance. (2) When weighing, put the weight on the left board and the weight on the right board. Weight should be taken with tweezers, first add the weight with large mass, and then add the weight with small mass. (3) Weighing dry solid drugs should be weighed on paper.

(4) Easily deliquescent and corrosive drugs (such as sodium hydroxide) must be weighed in glassware. ⑤ After weighing, put the weight back into the weight box and move the roaming code back to zero.

(2) The measuring cylinder is used to measure the volume of liquid, and its accuracy is not high.

Precautions for use: ① Do not heat and measure hot liquid, do not use it as a reaction container, and do not dilute the solution with a measuring cylinder. (2) When measuring liquid, the measuring cylinder must be flat, and the line of sight should be kept level with the lowest concave liquid level in the measuring cylinder, and then the liquid volume should be read out.

(3) The volumetric flask is used to accurately prepare a solution with a certain volume and concentration. Check whether there is air leakage before use. Transfer the solution to a volumetric flask by draining water from a glass rod.

Precautions for use: ① Only the solution with the specified volume on the volumetric flask can be prepared. ② The volume of the volumetric flask is calibrated at 20℃, and the temperature of the solution transferred to the flask should be around 20℃.

(4) The burette is an instrument for accurately measuring a certain volume of liquid. A burette with a glass piston is an acidic burette, and a burette with a rubber tube with a glass ball in it is an alkaline burette.

Precautions for use: ① Acid burette and alkaline burette cannot be mixed. ② ② The expected reading of ②②25ml and 50mL burettes is 0.0 1mL. (3) Before filling, rinse with lotion and water in turn, and wet the burette with the liquid to be filled. ④ When adjusting the liquid level, the tip of the dropper should be filled with solution to keep the liquid level at a certain scale below "0" or "0". When reading, the line of sight is flush with the most concave point of the liquid level in the tube.

(5) The gas measuring device can be assembled by a jar and a measuring cylinder. As shown in the figure. Water discharged into the measuring cylinder

This volume is the volume of gas generated at this temperature and pressure. Suitable for measuring water-insoluble substances.

Gas volume.

4. Other tools

Iron frame (iron clamp, iron ring) crucible clamp burning spoon medicine spoon glass rod thermometer condenser tube mirror gas bottle jar jar dropper sink mortar test tube rack tripod dryer

Second, the basic operation of chemical experiment

1, instrument cleaning

The standard for cleaning glass instruments is that the water film attached to the inner wall is uniform, neither gathering into water drops nor flowing down in strands.

I common method: you can add water to the container, choose a suitable brush, wash it repeatedly with decontamination powder or general detergent, and then rinse it with water.

Two. Special method: the container contains special substances and cannot be washed by common law. Special reagents can be selected to clean it by using organic solvents or chemical reactions.

2. Access to medicines

(1) Many drugs used in the laboratory are flammable, explosive, corrosive or toxic. Therefore, when using, we must strictly follow the relevant regulations and operating procedures to ensure safety. Don't touch drugs with your hands, don't put your nostrils to the mouth of the container to smell the smell of drugs (especially gas), and don't taste any drugs. Pay attention to saving medicine and take medicine in strict accordance with the dose prescribed in the experiment. If there is no prescribed dose, generally speaking, the minimum amount should be taken: liquid 1-2mL, and the solid only needs to cover the bottom of the test tube. The remaining drugs in the experiment can't be put back into the original bottle, can't be discarded at will, and can't be taken out of the laboratory, but should be put into the designated container.

(2) obtaining solid drugs

Take a spoon of solid medicine. When loading the solid powder into the test tube, in order to prevent the medicine from sticking to the nozzle and the tube wall, first tilt the test tube, carefully send the medicine spoon (or paper slot folded with small pieces of paper) filled with the medicine into the bottom of the test tube, and then make the test tube stand upright so that all the medicine falls to the bottom. Some blocky medicines can be picked up with tweezers.

(3) obtaining liquid medicine

When taking a very small amount of liquid, you can use a rubber pointed dropper to absorb it. When taking a large amount of liquid, the direct medicine pouring method can be adopted: when taking the liquid medicine from the narrow-mouth bottle, first take off the cork and pour it on the table, then pick up the bottle (the label should be hand-centered), and the bottle mouth should be next to the test tube mouth, so that the liquid can be slowly poured into the test tube. Pay attention to prevent the residual liquid medicine in the bottle mouth from flowing down to corrode the label. Generally, when the liquid is poured into a large-mouthed container, volumetric flask or funnel, a glass rod should be used for drainage.

3, the use of test papers

Type, application and usage of test paper, and matters needing attention

Test the acidity and alkalinity of litmus test paper (qualitative) ① test solution: put a small piece of test paper on a surface mirror or glass, and point it in the middle of the test paper with a glass rod dipped in the liquid to be tested to observe the color change.

② Test gas: Generally, first wet the test paper with distilled water and stick it on one end of the glass rod, then put the test paper on the mouth of the test tube containing the gas to be tested with the glass rod (be careful not to touch it) and observe the color change. (1) The test paper cannot enter the solution or contact with the nozzle.

② When measuring the pH value of the solution, the pH test paper should not be wetted first, because this is equivalent to diluting the original solution.

Testing acid-base strength with PH paper (quantitative)

Determination of sulfur dioxide and other bleaching substances by magenta test paper.

KI- starch test paper is used to detect oxidizing substances such as Cl2.

4. Preparation of solution

(1) Prepare a solution with a certain solute mass fraction.

Calculation: Calculate the mass of required solute and water. Convert the mass of water into volume. If the solute is a liquid, calculate the volume of the liquid.

Weighing: weighing the mass of solid solute with a balance; Simply take the required volume of liquid and water.

Dissolution: pour the solid or liquid solute into a beaker, add the required water, and stir with a glass rod to completely dissolve the solute.

(2) preparing a solution with a certain substance concentration.

Calculation: Calculate the mass of solid solute or the volume of liquid solute.

Weighing: Weigh the mass of solid solute with tray balance, and simply measure the volume of required liquid solute.

Dissolution: pour the solid or liquid solute into a beaker, add an appropriate amount of distilled water (about 1/6 of the volume of the prepared solution), stir it with a glass rod to dissolve it, cool it to room temperature, and discharge the solution into a volumetric flask.

Washing (transfer): Wash the beaker and glass rod with proper amount of distilled water for 2-3 times, and pour the washing liquid into the volumetric flask. Shake to mix the solution evenly.

Constant volume: Continue to carefully add water to the volumetric flask until the liquid level approaches the scale of 2-3m, and then add water with a rubber dropper to make the concave surface of the solution just tangent to the scale. Tighten the volumetric bottle cap and shake well.

5. Filtration is a method to remove impurities insoluble in solvents.

Attention should be paid to when filtering:

① Sticking: Fold the filter paper, put it into the funnel, add a little distilled water to moisten it, and make the filter paper stick to the inner wall of the funnel.

② Low: the edge of filter paper should be slightly lower than the edge of funnel, and the liquid level in funnel should be slightly lower than the edge of filter paper.

③ Triclinic: When pouring liquid into the funnel, the Neko of the beaker should contact with the glass rod; Where there are three layers of filter paper, the bottom of the glass rod should be in slight contact with the filter; The end of the funnel neck should be in contact with the inner wall of the receiver, for example, a small amount of sediment in the raw salt should be removed by filtration.

6, neutralization titration

Preparation process ① Check whether the burette leaks; (2) cleaning burette and conical flask; (3) wetting and washing the burette containing the standard solution and the burette containing the liquid to be tested with a small amount of standard solution; (4) Filling liquid, discharging bubbles, zeroing and recording initial readings.

Attitude during titration: control the piston or ball with the left hand, shake the conical flask with the right hand, and observe the color change and dropping speed of the solution in the conical flask with the eyes.

Dropping speed: drop by drop, and shake it drop by drop when it is near the end.

End point: The end point is the last drop, which obviously changes the color of the indicator. Record the reading.

7. Evaporation and crystallization evaporation are methods of concentrating solution, evaporating solvent or precipitating solute in crystal form. Crystallization is the process of separating crystals from solution by solute, which can be used to separate and purify the mixture of several soluble solids. The principle of crystallization is to reduce the solubility of each component in a certain solvent by evaporation or lowering the temperature, so as to precipitate crystals. When the evaporating dish is heated to evaporate the solution, the solution should be constantly stirred with a glass rod to prevent the droplets from splashing due to local high temperature. When more solids appear in the evaporating dish, stop heating, for example, the mixture of NaCl and KNO3 is separated by crystallization.

8. Distillation distillation is a method to purify or separate liquid mixtures with different boiling points. The process of separating various mixed liquids by distillation principle is called fractionation.

Attention during operation:

① Put a small amount of broken porcelain pieces in the distillation bottle to prevent the liquid from boiling.

(2) The position of the mercury ball of the thermometer should be on the same horizontal line with the lower edge at the bottom of the branch pipe.

③ The liquid in the distillation bottle should not exceed 2/3 of its volume and should not be less than 1/3.

(4) The cooling water in the condenser tube enters from the lower mouth and is discharged from the upper mouth.

⑤ The heating temperature should not exceed the boiling point of the substance with the highest boiling point in the mixture, such as the fractionation of petroleum.

9. Liquid separation and extract separation are methods to separate two liquids which are immiscible and have different densities. Extraction is a method of extracting solute from a solution composed of it and another solvent by using the solubility difference of solute in immiscible solvents. The selected extractant should meet the following requirements: immiscible with the solvent in the stock solution; Solute is much more soluble than the original solvent, and the solvent is volatile.

In the process of extraction, attention should be paid to:

(1) Pour the solution to be extracted and the extraction solvent into the separatory funnel from the upper opening in sequence, the amount of which should not exceed 2/3 of the volume of the funnel, plug the plug and vibrate.

(2) When vibrating, hold the neck of the upper mouth of the funnel with your right hand, press the plug with the root of your index finger, hold the cock with your left hand, control the piston with your fingers, invert the funnel and vibrate hard.

(3) Then, the separation funnel is allowed to stand, and the liquid is separated after layering, and the lower liquid is discharged from the funnel mouth and the upper liquid is poured out from the upper mouth. For example, using carbon tetrachloride to extract bromine from bromine water.

10. Sublimation Sublimation refers to the process that a solid substance directly changes into a gas state without going through a liquid state after absorbing heat. Using the sublimation characteristics of some substances, this substance is separated from other substances that do not sublimate when heated, such as heating to sublimate iodine, and the mixture of I2 and SiO2 is separated.

1 1. Dialysis uses a semi-permeable membrane (such as bladder membrane, parchment, cellophane, etc.). ) the colloid is separated from the molecules and ions mixed in it. Dialysis is often used to purify and refine colloidal solutions.

Third, the material storage and accident treatment

1. Reagent preservation

Chemicals may deteriorate due to exposure to light, heat, humidity and oxidation, and some chemicals may change their concentration because of their volatility or water absorption. Therefore, the storage methods of drugs are related to their chemical and physical properties.

(1) reagent bottle's selection principle: drug state should be calibrated-wide mouth for solid and narrow mouth for liquid.

The bottle stopper depends on the pH value. Keep the brown bottle away from light.

Preservation method, cause substance

Wide-mouth bottles or narrow-mouth bottles are convenient for taking bromine water and NaCl.

The rubber stopper of bottle stopper is corrosion-resistant, and nitric acid and liquid Br2 cannot be put.

Use a glass stopper to prevent sticking. NaOH, Na2CO3 and Na2S cannot be put in.

Plastic bottle silicon dioxide reacts with hydrogen fluoride, ammonium hydrogen fluoride and hydrogen fluoride.

Brown bottles can decompose nitric acid, chlorine water,

The liquid seal prevents oxidation and volatilization of P4 and liquid Br2.

Kerosene seal to prevent oxidation of sodium and potassium

Paraffin oil sealed anti-oxidation lithium

Sealed and volatile HCl, HNO3 and NH3.H2O

Antioxidant Na2SO3, H2S, Fe2+,

Anti-water absorption, carbon dioxide bleaching powder, alkali lime

Waterproof calcium chloride, calcium chloride, phosphorus pentoxide and concentrated sulfuric acid

1. Deteriorating reagents in the air: These reagents should be isolated or sealed from the air, and some reagents should be preserved by special measures.

Oxidation reagents: ferrous salt, active metal, white phosphorus, bisulfate, phenol, Na2SO3, etc.

CO2 absorbent: CaO, NaOH, Ca(OH)2, Na2O2, etc.

Moisture-absorbing reagents: P2O5, CaC2, CaO, NaOH, anhydrous CaCl2, concentrated H2SO4, anhydrous CuSO4, FeCl3? 6H2O, etc.

Weathering agent: Na2CO3? 10H2O、Na2SO4？ 10H2O, etc.

2. Reagents that are easy to decompose when exposed to light or heat: they should be stored in brown bottles and placed in a cool and dark place. Such as ammonia, hydrogen peroxide, silver nitrate, nitric acid, etc.

3. Volatile or sublimated reagents: These reagents should be stored in cold and dark places.

Volatile reagents: concentrated ammonia, concentrated hydrochloric acid, concentrated nitric acid, liquid bromine, ethyl acetate, carbon disulfide, carbon tetrachloride, gasoline, etc.

Easy sublimation reagent: iodine, naphthalene, etc.

4. Dangerous goods: This kind of reagents should be classified and stored away from fire sources.

Flammable reagents: organic solvents such as gasoline, benzene, ethanol, esters and red phosphorus, sulfur, magnesium, nitrocellulose, etc. It will burn in case of open fire. White phosphorus can spontaneously ignite.

Non-combustible reagents that are dangerous after contact with combustible substances are: potassium permanganate, potassium chlorate, potassium nitrate, sodium peroxide, etc.

Explosive reagents: nitrocellulose, ammonium nitrate, etc.

Highly toxic reagents: cyanide, mercury salt, yellow phosphorus, barium chloride, nitrobenzene, etc.

Highly corrosive reagents: strong acid, strong alkali, liquid bromine, methanol, phenol, hydrofluoric acid, acetic acid, etc.

5. Some reagents should not be protected for a long time, so they should be taken as needed. Such as ferrous sulfate solution, chlorine water, hydrogen sulfate, silver ammonia solution, etc.

2. Handling of common accidents

Accident handling method

When flammable organic matter such as alcohol catches fire in a small area, immediately cover it with a wet cloth.

Sodium, phosphorus and other fires are quickly covered with sand.

A small amount of acid (or alkali) drops on the table, immediately wipe it with a wet cloth, and then rinse it with water.

When a large amount of acid (or alkali) flows to the countertop, immediately use an appropriate amount of NaHCO3 solution (or dilute HAC) to act, and then rinse with water.

When the acid comes into contact with the skin or clothes, first wipe it with a rag, then rinse it with water, and then rinse it with a dilute solution of NaHCO3.

When lye comes into contact with the skin, rinse with more water first, and then rinse with boric acid solution.

If acid or alkali spills into your eyes, immediately rinse it repeatedly with water and blink constantly.

When phenol comes into contact with the skin, scrub it with alcohol and then rinse it with water.

When white phosphorus comes into contact with skin, wash the wound with CuSO4 _ 4 solution first, and then wet compress with diluted KMnO4 _ 4 solution.

Bromine dripping on the skin should be wiped off immediately, then washed off with non-toxic organic solvents such as dilute alcohol, and then coated with boric acid and vaseline.

Eating heavy metal salt by mistake should immediately take egg white or raw milk orally.

When mercury drops on the table or the ground, it should be immediately sprinkled with sulfur powder.

Fourthly, the gas generating device

(1) Device sequence: gasification device → purification device → reaction or collection device → tail gas removal device.

(2) Installation sequence: from bottom to top, from left to right.

(3) Operation sequence: assemble the instrument → check the air tightness → add medicine.

1, type of gas generating device

(1) design principle: select the reaction device according to the reaction principle, reactant state and reaction conditions.

(2) Basic types of equipment:

Device type solid reactant (heated) solid-liquid reactant (unheated) solid-liquid reactant (heated)

equipment

Schematic diagram

Main instruments

Typical gases are H2 such as O2, NH3 and CH4, Cl2 such as CO2 and H2S, HCl and CH2=CH2.

Operation points (l) The test tube mouth should be slightly inclined downwards to prevent the generated steam from flowing backwards after condensation at the tube mouth, thus causing the test tube to break.

(2) The iron clip should be clamped at 1/3 from the test tube mouth.

(3) Don't extend the catheter on the rubber stopper into the test tube for too long, otherwise it will hinder the gas export. (1) When using a simple device, if a long-necked funnel is used, the lower mouth of the funnel neck should be below the liquid level, otherwise it will not play the role of liquid seal;

(2) The added liquid reactant (such as acid) should be appropriate.

(3) The mixture of bulk solid and liquid reacts at room temperature to prepare gas, which can be prepared by Kipp generator. (1) Add the solid medicine into the flask first, and then add the liquid medicine.

(2) Use the separating funnel correctly.

Reaction principle of preparation of several gases

1、O2 2KClO3 2KCl+3O2↑

2k MnO 4 k2mno 4+MnO 2+O2↓

2H2O 2·2H2O+O2↑

2、NH3·2nh 4 cl+Ca(OH)2 CaCl 2+2 NH3 ↑+ 2H2O

NH3？ H2O NH3↑+H2O

3、CH4·ch 3c oona+NaOH·na2co 3+CH4↑

4.H2 zinc+sulfuric acid (diluted) = zinc sulfate +H2 =

5、CO2 CaCO3+2HCl=CaCl2+CO2↑+H2O

6. SO2 Na2SO4+H2SO4 (concentrated) = Na2SO4+SO2 =+H2O

7.NO2 copper+nitric acid (concentrated) = copper (nitric acid) 2+2no2 =+2h2o.

8.NO 3Cu+8HNO3 (diluted) = 3cu (NO3) 2+2no =+4h2o.

9、C2H2 CaC2+2H2O→Ca(OH)2+CH≡CH↑

10, Cl2 MnO2+4HCl (concentrated) mncl2+Cl2 =+2h2o.

1 1、C2H4 C2H5OH CH2=CH2↑+H2O

12, N2 sodium nitrite+ammonium chloride and sodium chloride+N2 = +N2↑+2H2O

2. Collecting device

The main basis for selecting the collection method is the density and water solubility of the gas. Based on the physical properties of chlorine gas, chlorine gas can be collected by exhausting air upwards. Because chlorine is insoluble in saturated brine, it can also be collected by discharging saturated brine.

(1) design principle: according to the solubility or density of oxidation.

(2) Basic types of equipment:

Device type: drainage (liquid) gas gathering method, upward gas gathering method and downward gas gathering method.

fix

Schematic diagram

Scope of application The density of water-insoluble gas (liquid) is greater than that of air and less than that of air.

Typical gases H2, oxygen, nitrogen oxide, carbon monoxide, methane,

CH2=CH2、CH≡CH Cl2、H Cl、CO2、SO2、H2S H2、NH3、CH4

3. Purification and drying device

There are three kinds of tail gas absorption treatment devices: ① inverted funnel-water-soluble gas; (2) Glass tube-absorbs gas that can be dissolved in water or solution (such as absorbing Cl2); With NaOH solution); (3) Ignition method-dealing with carbon monoxide

(1) design principle: according to the state and conditions of the purified drug.

(2) Basic types of equipment:

equipment

Type liquid impurity remover (unheated) solid impurity remover (unheated) solid impurity remover (heated)

suit

range

fix

Schematic diagram

(3) Selection of gas purifying agent

The selection of gas absorbent should be determined according to the properties of gas and impurities. The selected absorbent can only absorb impurities in the gas and cannot react with the purified gas. Generally speaking: ① gas impurities easily soluble in water can be absorbed by water; ② Acidic impurities can be absorbed by alkaline substances; ③ Alkaline impurities can be absorbed by acidic substances; (4) Moisture can be absorbed by desiccant; ⑤ Substances that can react with impurities to produce precipitates (or soluble substances) can also be used as absorbents.

(4) Type and selection of gas desiccant

Commonly used gas desiccant can be divided into three categories according to pH:

(1) acidic desiccant, such as concentrated sulfuric acid, phosphorus pentoxide and silica gel. Acidic desiccant can dry acidic or neutral gases, such as CO2, SO2, NO2, HCl, H2, Cl2, O2 and CH4.

(2) Alkaline desiccant, such as quicklime, alkali lime and solid NaOH. Alkaline desiccant can be used to dry alkaline or neutral gases, such as NH3, H2, O2 and CH4.

③ Neutral desiccant, such as anhydrous calcium chloride, can dry neutral, acidic and alkaline gases, such as O2, H2 and CH4.

When selecting desiccant, acid desiccant cannot be used for alkaline gas, and alkaline desiccant cannot be used for acid gas. Oxidizing desiccant cannot be used for reducing gas. Substances that can react with gases cannot be selected as desiccants, such as CaCI2 _ 2, which cannot be used to dry NH3. 8NH3), NH3, H2S, HBr, HI, etc. Cannot be dried with concentrated H2SO4.

Matters needing attention in gas purification and drying

In general, if the solution is used as the impurity removal reagent, the impurities are removed first and then dried; If impurities are removed by heating, dry them first and then heat them.

The tail gas of toxic and harmful gases must be absorbed (or ignited) with an appropriate solution to make it non-toxic, harmless and pollution-free. For example, Cl2, SO2 and Br2 (vapor) in the tail gas can be absorbed by NaOH solution; H2S in tail gas can be absorbed by copper sulfate or sodium hydroxide solution; The tail gas CO can be converted into CO2 gas by ignition.

Separation, purification and identification of common substances in verbs (abbreviation of verb)

1. General physical method-separation according to the difference of physical properties of substances.

Physical separation method of mixture

Methods Application scope Examples of main instruments for attention

Solid+liquid evaporation soluble solid-liquid separation; Alcohol lamp, evaporating dish and glass rod ① are constantly stirred; (2) finally heating with waste heat; ③ The volume of liquid shall not exceed 2/3 of that of NaCl (H2O).

Solute with large solubility difference between solid and solid crystal precipitates NaCl(NaNO3 _ 3).

Alcohol lamp I2(NaCl) can sublimate solids and separate non-sublimated substances.

Solid+liquid filtration separates soluble substances from insoluble substances. The funnel and beaker ① have one corner, two low corners and three bulges; (2) sediment should be washed clean; ③ The quantitative experiment should be "non-destructive" to NaCl(CaCO3).

Liquid+liquid extraction solutes have different solubility in mutually immiscible solvents, so check the leakage before separating the solute from the separating funnel (1); ② Requirements for extractant; (3) communicate the atmosphere inside and outside the funnel; ④ Pour out the upper liquid from the upper mouth, and extract Br2 from bromine water.

Ethyl acetate and saturated Na2CO3 solution were separated by a separatory funnel.

Distillation bottle, condenser tube, thermometer and horn tube are used for distillation separation of mixed solutions with different boiling points. (2) condensed water is introduced from the lower opening; ③ Add ethanol, water, I2 and CCl4.

Dialysis separates colloid from molecules and ions mixed in it. Semipermeable membrane replaces distilled water, starch and sodium chloride.

Salting out adds some salt to reduce the solubility of solute, and separates out solid salt or concentrated solution protein solution, sodium stearate and glycerol for beaker.

Gas+gas washing gas Soluble gas and insoluble gas are separated, and CO2(HCl) grows in and out of the washing drum.

Ice water NO2(N2O4) is often used to liquefy U-tubes with different boiling points.

2. Chemical separation and purification of substances

Generally, the separation of substances can be carried out by chemical methods first, and then appropriate separation methods can be adopted according to the characteristics of the mixture (see basic operation of chemistry).

When separating and purifying substances by chemical methods, attention should be paid to:

(1) It is best not to introduce new impurities;

(2) The quality of the purified substance cannot be lost or reduced.

③ The experimental operation should be simple, not complicated. When removing impurities from the solution by chemical methods, it is necessary to add excessive separation reagents to make the separated substances or ions as clean as possible. In the multi-step separation process, the added reagent should be able to remove previously added irrelevant substances or ions.

For inorganic solutions, the following methods are usually used for separation and purification:

(1) Generation precipitation method (2) Generation gas method (3) Redox method (4) Mutual transformation between normal salt and acid salt method (5) Removal of impurities by amphoteric substances (6) Ion exchange method.

Impurity removal methods of common substances

Main operation methods of impurity removal reagent for serial number original

Solid conversion gas for 1 N2 O2 hot copper wire mesh

Carbon dioxide H2S copper sulfate solution washing gas

Gas washing of 3 CO CO2 NaOH solution

The solid conversion gas of 4c2oco hot CuO

5 CO2 HCI saturated NaHCO3 washing gas

6 H2S hydrochloric acid saturated NaHS washing gas

7 SO2 HCI saturated NaHSO3 washing gas

8 CI2 HCI saturated brine washing gas

9 CO2 SO2 saturated NaHCO3 washing gas

10 carbon powder MnO2 _ 2 concentrated hydrochloric acid (to be heated) is filtered.

1 1m no2c- heating and combustion

12 carbon powder CuO diluted acid (such as diluted hydrochloric acid) filtration.

13 al2o 3 fe2o 3 NaOH (excess), CO2 filtration.

Filtration of 14 fe2o 3 al2o 3 NaOH solution

15 al2o 3 SiO 2 hydrochloric acid `ammonia water filtration

16 silicon dioxide zinc oxide hydrochloric acid solution is filtered,

17 baso 4 baco 3 HCl or dilute H2SO4 filtration.

Acid conversion of 18 sodium bicarbonate solution with Na2CO3 CO2

19 sodium chloride solution sodium bicarbonate hydrochloric acid conversion method

Transformation of FeCI _ 2 Ci2 in 20 FeCI3 _ 3 _ 3 solution with oxidant.

CuCI2 Fe and CI2 filtration of 2 1 FeCl 3 solution

Transformation method of FeCI _ 3 Fe reducing agent in 22 FeCI2 _ 2 _ 2 solution

23 CuO Fe (magnet) adsorption

Dialysis of 24 Fe(OH)3 colloidal FeCI3 with distilled water

25 CuS FeS dilute hydrochloric acid filtration

26 I2 crystal sodium chloride-heating sublimation

Thermal decomposition of NH4Cl- 27 sodium chloride crystal

Recrystallization of 28 KNO3 crystal with distilled water of sodium chloride.

29 ethylene SO2, H2O alkali lime plus solid conversion method

30 ethane C2H4 bromocarbon tetrachloride solution washing gas

Separation of dilute NaOH solution of 3 1 bromobenzene br2

Separation of 32 Toluene Phenol Sodium Hydroxide Solution

Distillation of 33 Hexaldoacetic Acid with Saturated Na2CO3

Distill fresh CaO with 34 ethanol and water (small amount)

35 phenol benzene NaOH solution, CO2 separation.

3. Identification of substances

There are usually three kinds of tests for substances: identification, identification and inference. Their similarities are: according to the special properties and characteristic reactions of substances, appropriate reagents and methods are selected to accurately observe the obvious phenomena in the reaction, such as color change, precipitation formation and dissolution, gas generation and odor, flame color and so on. And make judgments and inferences.

The identification of inspection types is to distinguish between different substances by experiments.

According to the characteristics of a substance, the composition of the substance is detected through experiments to determine whether it is this substance.

Inference According to the known experiments and phenomena, analyze and judge, determine what substance is detected, and point out what may exist and what may not exist.