From the point of view of experimental chemistry, the safety of chemical experiment 1 and (1), the experiment of toxic gas should be carried out in a ventilated kitchen, and proper treatment (absorption or ignition, etc.) should be paid attention to. ) exhaust gas.
In the experiment of flammable and explosive gases, attention should be paid to purity inspection, and the tail gas should be burned or properly treated. (2) Burn should be treated by a doctor.
(3) Sprinkle concentrated acid on the experimental platform, first neutralize it with Na2CO3 (or NaHCO3), and then wash it with water. The concentrated acid on the skin should be wiped off with a dry rag first, and then rinsed with water.
Concentrated acid splashed into eyes should be washed with dilute sodium bicarbonate solution first, and then treated by a doctor. (4) Sprinkle concentrated alkali on the experimental platform, first neutralize it with dilute acetic acid, and then rinse it with water.
The concentrated alkali on the skin should be washed with plenty of water first, and then coated with boric acid solution. Concentrated alkali splashed into eyes, washed with water, then washed with boric acid solution.
(5) The fire of sodium and phosphorus should be covered with sand. (6) If flammable organic substances such as alcohol catch fire in a small area, quickly cover it with a wet rag.
2. Separation and purification of mixture, methods of separation and purification, matters needing attention of separated substances, application examples, filtration, separation of solid-liquid mixture, one stick, two lows, and three ways to prevent liquid boiling by purification, distillation, purification of crude salt or separation of liquid mixtures with different boiling points, the position of mercury ball in thermometer, such as the flow direction of water in condenser tube in petroleum distillation, such as distillation and extraction of petroleum, and the different solubility of solute in mutually immiscible solvents. The solubility of solute is much greater than that of original solvent. Using carbon tetrachloride to extract bromine and iodine from bromine water, and separating immiscible liquids. Open the upper piston or make the groove on the piston and the water hole on the funnel communicate with the air inside and outside the funnel. Open the piston, let the lower liquid flow out slowly, close the piston in time, and pour the upper liquid out from the upper end. For example, if bromine and iodine in bromine water are extracted with carbon tetrachloride, then the mixture is separated, evaporated and crystallized to separate and purify several soluble solids. When heating the evaporating dish to evaporate the solution, the glass rod should be used to continuously stir the solution. When more solids appear in the evaporating dish, the heating is stopped to separate the mixture of NaCl and KNO3. Third, the phenomenon that ions are added to the reagent in ion inspection: ionic equation Cl- AgNO3, dilute HNO3 produces white precipitate Cl-+Ag+=AgCl↓ SO42- dilute HCl, and BaCl2 white precipitate SO42-+Ba2+=BaSO4↓ IV. Precautions for impurity removal: In order to remove all impurities, add. However, excess reagents must be easily removed in subsequent operations.
5. Unit of the amount of substance-mole 1. The quantity of matter (n) is a physical quantity of a group containing a certain number of particles. 2. Molar: Any particle containing 6.02 * 1023 particles, collectively referred to as 1 mol.
3. Avon Garderot constant: 6.02 X 1023mol- 1 is called Avon Garderot constant. 4. The amount of substance = the number of particles contained in the substance /Avon Garderot constant n =N/NA 5. Molar mass (M)( 1) Definition: The mass per unit amount of substance is called molar mass. (2) Unit: g/mol or g ... mol- 1(3) Value: equal to particles. Molar mass (n = m/M) VI. Molar volume of gas 1. Definition of molar volume of gas (Vm)( 1): The volume occupied by gas per unit substance is called the molar volume of gas. (2) Unit: L/mol 2. Amount of substance = volume of gas/molar volume of gas n=V/Vm 3. Vm = 22.4 l/mol VII. Application of the amount of substances in chemical experiments 1. Quantity and concentration of substances. (1) Definition: The physical quantity of solution composition is expressed by the quantity of substance of solute B contained in unit volume solution, which is called the concentration of substance of solute B..
(2) unit: mol/L(3) substance concentration = substance/solution volume of solute CB = nB/V 2. Basic principle of material concentration preparation (1): According to the volume of the solution to be prepared and the material concentration of the solute, calculate the mass or volume of the required solute by the method of material concentration calculation, and dilute the solute with solvent in the container. Obtaining the solution to be prepared. (2) The main operation is a. Check whether there is water leakage. B. Calculate the prepared solution 1. Weigh it. 3 dissolve it. 4 turn around. 5 wash it clean. 6 determine the volume. 7 shake well. 8 store the solution. Matters needing attention: a. Select a volumetric flask with the same volume as the solution to be prepared. B, check whether there is water leakage before use. C can't be directly dissolved in the volumetric flask. D, if completely dissolved. Under the condition of constant volume, when the liquid level is away from the scale line 1-2 cm, use a dropper to observe that water is added until the lowest point of the liquid level is tangent to the scale. 3. Solution dilution: C (concentrated solution)? V (concentrated solution) =C (diluted solution)? V (dilute solution) I. Classification of substances A system obtained by dispersing one (or more) substances in another (or more) substances is called a dispersion system. The dispersed substance is called dispersoid (which can be gas, liquid or solid), and the substance containing dispersoid is called dispersant (which can be gas, liquid or solid).
Comparison of three dispersion systems: solution, colloid and suspension. Can the appearance characteristics of dispersoid particle size /nm be judged by whether the filter paper has Tindal effect? If the solution is less than 1, it is uniform, transparent and stable; The colloid of sucrose solution is homogeneous, transparent and stable between 1 ~ 100, and it is Fe(OH). 3 colloidal turbid liquid is more than 100, uneven, opaque and unstable. 2. Chemical changes of substances 1. Various chemical changes can occur between substances, and chemical changes can be classified according to certain standards. (1) can be divided into: a, combination reaction (A+B=AB)B, decomposition reaction (AB=A+B) C, displacement reaction (A+BC=AC+B) D, double decomposition reaction (AB+CD = AD+CB.
It mainly includes metathesis reaction and redox reaction with ions. B. Molecular reaction (non-ionic reaction) (3) According to whether there is electron transfer in the reaction, the reaction can be divided into: a. Redox reaction: the essence of the reaction with electron transfer (gain or loss or shift): the valence of elements has changed before and after the reaction; B. Non-redox reaction 2. Ion reaction (1), electrolyte: in.
2. Finishing the chemical knowledge of senior one.
Compulsory (1) general review (content part) When doing toxic gas experiments from experimental chemistry I, chemical experiment safety 1, (1), it should be carried out in a ventilated kitchen, and attention should be paid to proper handling (absorption or ignition, etc.). ) exhaust gas.
In the experiment of flammable and explosive gases, attention should be paid to purity inspection, and the tail gas should be burned or properly treated. (2) Burn should be treated by a doctor.
(3) Sprinkle concentrated acid on the experimental platform, first neutralize it with Na2CO3 (or NaHCO3), and then wash it with water. The concentrated acid on the skin should be wiped off with a dry rag first, and then rinsed with water.
Concentrated acid splashed into eyes should be washed with dilute sodium bicarbonate solution first, and then treated by a doctor. (4) Sprinkle concentrated alkali on the experimental platform, first neutralize it with dilute acetic acid, and then rinse it with water.
The concentrated alkali on the skin should be washed with plenty of water first, and then coated with boric acid solution. Concentrated alkali splashed into eyes, washed with water, then washed with boric acid solution.
(5) The fire of sodium and phosphorus should be covered with sand. (6) If flammable organic substances such as alcohol catch fire in a small area, quickly cover it with a wet rag.
2. Separation and purification of mixture, methods of separation and purification, matters needing attention of separated substances, application examples, filtration, separation of solid-liquid mixture, one stick, two lows, and three ways to prevent liquid boiling by purification, distillation, purification of crude salt or separation of liquid mixtures with different boiling points, the position of mercury ball in thermometer, such as the flow direction of water in condenser tube in petroleum distillation, such as distillation and extraction of petroleum, and the different solubility of solute in mutually immiscible solvents. The solubility of solute is much greater than that of original solvent. Using carbon tetrachloride to extract bromine and iodine from bromine water, and separating immiscible liquids. Open the upper piston or make the groove on the piston and the water hole on the funnel communicate with the air inside and outside the funnel. Open the piston, let the lower liquid flow out slowly, close the piston in time, and pour the upper liquid out from the upper end. For example, if bromine and iodine in bromine water are extracted with carbon tetrachloride, then the mixture is separated, evaporated and crystallized to separate and purify several soluble solids. When heating the evaporating dish to evaporate the solution, the glass rod should be used to continuously stir the solution. When more solids appear in the evaporating dish, the heating is stopped to separate the mixture of NaCl and KNO3. Third, the phenomenon that ions are added to the reagent in ion inspection: ionic equation Cl- AgNO3, dilute HNO3 produces white precipitate Cl-+Ag+=AgCl↓SO42- dilute HCl, and BaCl2 white precipitate SO42-+Ba2+=BaSO4↓ IV. Precautions for impurity removal: In order to remove all impurities, add. However, excess reagents must be easily removed in subsequent operations.
5. Unit of the amount of substance-mole 1. The quantity of matter (n) is a physical quantity of a group containing a certain number of particles. 2. Molar: Any particle containing 6.02 * 1023 particles, collectively referred to as 1 mol.
3. Avon Garderot constant: 6.02 X 1023mol- 1 is called Avon Garderot constant. 4. Amount of substance = number of particles contained in substance /Avon Garderot constant n =N/NA5. Molar mass (M)( 1) Definition: The mass per unit amount of substance is called molar mass. (2) Unit: g/mol or g ... mol- 1(3) Value: equal to particles. Molar mass (n = m/M) VI. Molar volume of gas 1. Definition of molar volume of gas (Vm)( 1): The volume occupied by gas per unit substance is called the molar volume of gas. (2) Unit: L/mol 2. Amount of substance = volume of gas/molar volume of gas n=V/Vm 3. Vm = 22.4 l/mol VII. Application of the amount of substances in chemical experiments 1. Quantity and concentration of substances. (1) Definition: The physical quantity of solution composition is expressed by the quantity of substance of solute B contained in unit volume solution, which is called the concentration of substance of solute B..
(2) unit: mol/L(3) substance concentration = substance/solution volume of solute CB = nB/V 2. Basic principle of material concentration preparation (1): According to the volume of the solution to be prepared and the material concentration of the solute, calculate the mass or volume of the required solute by the method of material concentration calculation, and dilute the solute with solvent in the container. Obtaining the solution to be prepared. (2) The main operations are: a. Check whether there is water leakage. B. Calculate the prepared solution χ 1. χ 2 weighing. χ 3 dissolution. χ 4 metastasis. χ 5 wash. χ 6 Constant volume. Shake χ 7 well. χ 8 storage solution. Note: A Select a volumetric flask with the same volume as the solution to be prepared. B. before use, check whether it is available. Wait until it's warm. E. When the volume is constant, use a dropper at the place where the liquid level is away from the scale line 1-2 cm, and observe by looking down that water is added until the lowest point of the liquid level is tangent to the scale. V (concentrated solution) =C (diluted solution)? V (dilute solution) chemical substances and their changes I. Classification of substances The system obtained by dispersing one (or more) substances in another (or more) substances is called dispersion system. The dispersed substance is called dispersoid (which can be gas, liquid or solid), and the substance containing dispersoid is called dispersant (which can be gas, liquid or solid).
Comparison of three dispersion systems: solution, colloid and suspension. Can the appearance characteristics of dispersoid particle size /nm be judged by whether the filter paper has Tindal effect? If the solution is less than 1, it is uniform, transparent and stable; The colloid of sucrose solution is homogeneous, transparent and stable between 1 ~ 100, and it is Fe(OH). 3 colloidal turbid liquid is more than 100, uneven, opaque and unstable. 2. Chemical changes of substances 1. Various chemical changes can occur between substances, and chemical changes can be classified according to certain standards. (1) can be divided into: a, combination reaction (A+B=AB)B, decomposition reaction (AB=A+B)C, displacement reaction (A+BC=AC+B)D, double decomposition reaction (AB+CD = AD+CB.
It mainly includes metathesis reaction and redox reaction with ions. B, molecular reaction (nonionic reaction) (3) According to whether there is electron transfer in the reaction, the reaction can be divided into: a, redox reaction: reverse.
3. Summary of compulsory knowledge points in senior high school chemistry
High school chemistry compulsory 2 knowledge points summary Chapter I Periodic Law of Material Structure Elements 1. Atomic structure proton (z) nuclear note: neutron (n) mass number (A)= proton number (Z)+ neutron number (N) 1. Atomic number of atom (A X) = nuclear charge number = proton number = extranuclear electron number of atom (Z familiar 1~20) Extranuclear electron arrangement of elements: H Li and Be B C N O F Ne Na Mg Al Si P S Cl ar K Ca 2. The arrangement law of extranuclear electrons: ① electrons are always arranged in the lowest energy electron layer first; ② The maximum number of electrons contained in each electron layer is 2n2；; ③ The number of electrons in the outermost layer shall not exceed 8 (the number of electrons in the K layer shall not exceed 2), and the number of electrons in the second outer layer shall not exceed 18. The number of electrons in the penultimate layer does not exceed 32. Electron layer: one (lowest energy) two three four five six seven corresponding symbol: K L M N O P Q3. Element, nuclide, isotope: the general name of the same kind of atoms with the same nuclear charge. Nuclide: An atom with a certain number of protons and a certain number of neutrons. Isotope: Different atoms of the same element have the same number of protons but different numbers of neutrons, which are called isotopes. (For atoms) 2. Periodic Table of Elements 1. Arrangement principle: ① Arrange from left to right in the order of increasing atomic number; (2) arranging the elements with the same number of electron layers horizontally from left to right; (Number of cycles = number of electron layers of atoms) ③ Arrange the elements with the same number of electrons in the outermost layer in a vertical line from top to bottom in the order of increasing number of electron layers; Main family number = the outermost electron number of the atom; 2. Structural features: the number of electron layers outside the nucleus; Element type, first period, 65438+. Prime short period second period 2 8 kinds of elements third period 3 8 kinds of elements (7 lines) fourth period 4 18 kinds of elements (7 periods) fifth period 5 18 kinds of elements sixth period 6 32 kinds of elements seventh period 7 Not filled (with 26 kinds of elements) Table main family: ia ~ ⅶ a * * * seven. Periodic law of elements 1. Periodic law of elements: The properties of elements (extranuclear electron configuration, atomic radius, valence, metallicity and nonmetal) change periodically with the increase of nuclear charge. The periodic change of element properties is essentially the inevitable result of the periodic change of electron configuration outside the nucleus of an element. 2. The gradual change law of the properties of the same periodic elements \ x0965438+x091na \ x0912mg \ x0913al \ x0966. The number of electron layers of x0915p \x0916s \x0917cl \ x0918ar (1) electron configuration \ x09 is the same, and the number of outermost electrons increases in turn (2) atomic radius. X09+7-1\ x09-(4) x09h2s \ x09HCl \ x09-(7) the difficulty of combining with H2 \ x09-x09 from difficult to easy-(8) the stability of hydride \ x09-x09 is enhanced-(9) the chemical formula of the highest valence oxide \ x099. X09x09 —— the highest valence oxide corresponds to hydrate \x09( 10) chemical formula \ x09NaOH \ x09mg (oh) 2 \ x09al (oh) 3 \ x09h2sio3 \ x09 acid enhancement —— alkali metal element of group ia: Li Na K Rb Cs Fr (Fr is the most metallic element, located in the period. The method for judging the strength of metal and nonmetal elements: (1) Strong (weak) metallicity-① Simple substance reacts with water or acid to generate hydrogen easily (difficultly); (2) Strong (weak) alkalinity of hydroxide; ③ Exchange reaction (forced weak) Fe+CuSO4=FeSO4+Cu. (2) Strong nonmetal (weak)-① Simple substance is easy (difficult) to react with hydrogen; ② The generated hydride is stable (unstable); ③ The hydrate (oxyacid) of the highest valence oxide has strong (weak) acidity; ④ substitution reaction (forced weak) 2nab r+Cl2 = 2nac+br2. (1) Comparison in the same period: the reaction of metal: Na & gtMg & gt aluminum with acid or water: from easy to difficult alkali: NaOH >；; Non-metallic properties of magnesium hydroxide-GTAL (OH) 3: Sicl >: Reaction of Br>I with hydrogen: from easy to difficult hydride stability: HF> HCl & gthbr & gthi (Ⅲ) Metal degree: Lina+>; k+& gt； r b+ & gt； Cs+\x09 nonmetal: F & gtCl & gtBr & gtI oxidizability: F2 & gtCl2 & gtBr2 & gtI2 reducibility: the total energy of F-E products. For exothermic reaction, the total energy of E reactant, H2CO32C3COOH+CaCO3 = 2 (CH3 Chief Operating Officer) 2ca+CO2 ↑+H2O (forced weak) ② esterification reaction. Basic Nutrients The nutrients in food include: sugar, oil, protein, vitamins, inorganic salts and water. People used to call them sugar. Oil and protein are the basic nutrients in animal and plant foods. The species \x09 yuan \x09 stands for \x09 molecular sugar \x09 monosaccharide \x09C H O\x09 glucose \ x09c12o6 x09 glucose and fructose are isomers, and fructose cannot hydrolyze \ x09 disaccharide \ x09. X09c12h22o11\ x09 Sucrose and maltose are isomers, which can be hydrolyzed. Maltose \x09\x09 polysaccharide \ x09H0 \ x09 starch \x09(C6H 10O5)n\x09 starch and cellulose have different n values. X09\x09 oil \x09 oil \x09C H O\x09 vegetable oil \x09 unsaturated higher fatty acid glyceride \x09 contains C=C bond, which can generate addition reaction and hydrolysis reaction \x09C H O\x09 animal fat \x09C saturated higher fatty acid glyceride \x09C-C bond, protein on S P, etc.
4. Organize the key points of high school chemistry knowledge
I am a graduate of 2009. I was admitted to Harbin Normal University to study chemistry. In fact, learning chemistry is like learning a subject that you are good at. You master the basic knowledge first, and then integrate theory with practice, that is, do the problem and think repeatedly during the process. Doing so is equivalent to practice and sublimation. Learning the same knowledge takes time, and hard work and persistence will pay off.
Chemistry is generally divided into organic and inorganic, in which chemical equations are very important (not to be ignored). Remember the characteristics of a substance and summarize the experimental phenomena in the experiment (the order cannot be reversed). This is the process of learning, but we must sum it up ourselves, not just by teachers and classmates.
Problem solving: First, analysis. Since you study chemistry, you must be a science student. When learning the theory class, we should cultivate careful thinking logic, analyze every detail and key hint, then connect with the practical knowledge we have learned, and finally solve the problem seriously.
The above is the knowledge summary and problem-solving method of chemistry in senior high school, and it is also the learning method of other disciplines.
5. Help to provide some high school chemistry knowledge summary.
Senior high school chemistry is mainly divided into two parts: 1. Inorganic chemistry II. Organic chemistry topics are mainly divided into 1. The amount of substance and its related calculation (including concentration, PH value, etc. ) 2. Material inference (inorganic inference and organic inference respectively) 3. In fact, there are not many chemical contents in the experimental questions, and there are only a few things to be tested. If you do more questions, you will naturally feel the law.
The calculation of chemical problems is mainly the proportional conversion of substances, which is not difficult. After all, math is used from time to time. However, the difficulties are generally in material inference and experiment. Material inference needs to have a certain memory of the characteristics of the chemical substances under investigation, which is an accumulation process and can be made up by doing problems.
The trouble lies in the experimental questions, because there are many aspects and angles of investigation, so it is difficult to summarize them. In fact, at the end of the review of senior three, the most worthwhile thing for a paper is the experimental problem, which can be done very simply, but if it is difficult, it must be the details. I hope you are diligent, chemistry is actually very simple.
6. High school chemistry knowledge encyclopedia
Chloroform: CHCl3 calcium carbide: CaC2 calcium carbide gas: C2H2 (acetylene) chlorofluorocarbon: it is a good refrigerant and toxic, but it destroys O3 layer.
Alcohol, ethanol: C2H5OH cracking gas components (petroleum cracking): olefins, alkanes, alkynes, H2S, CO2, CO, etc. Composition of coke oven gas (coal dry distillation): H2, CH4, ethylene, CO, etc.
Acetic acid: glacial acetic acid, vinegar CH3COOH glycerin, glycerin: C3H8O3 carbolic acid: phenol ant aldehyde: formaldehyde HCHO glucose: C6H 12O6 fructose: C6H 12O6 sucrose: c12h22o1.
7. High school chemistry, important knowledge induction
The first chapter of experimental chemistry. Isolation, purification and identification of common substances 1. Common physical method-separation according to the difference of physical properties of substances.
The method of physical separation and the method of mixture are applicable to the main instruments. Examples Solid+liquid evaporation Soluble solid is separated from liquid. Alcohol lamp, evaporating dish and glass rod ① are constantly stirred; (2) finally heating with waste heat; (3) 2/3 NaCl(H2O) solid with no more than liquid volume+solute with great solubility difference in solid crystallization is separated. Sublimation of NaCl(NaNO3) can separate solids from non-sublimed substances. Alcohol lamp I2(NaCl) 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 In quantitative experiment, NaCl(CaCO3) liquid+liquid should be used to extract solutes with different solubility in immiscible solvents, and the solutes should be separated by a separating funnel. ② Requirements for extractant; (3) communicate the atmosphere inside and outside the funnel; (4) pouring out the upper liquid from the upper opening, extracting Br2 from the bromine water for liquid separation, separating the immiscible liquid with a separating funnel, distilling out ethyl acetate and saturated Na2CO3 solution, and separating mixed solutions with different boiling points; Distillation bottles, condensation tubes, thermometers and trumpet tubes; (2) condensed water is introduced from the lower opening; (3) Adding broken ceramic tiles, ethanol and water, I2 and CCl4, dialyzing to separate colloid from molecules and ions mixed in it, replacing distilled water, starch and NaCl, adding some salt to reduce the solubility of solute, and separating out beaker. Gas cylinders were washed with solid salt or concentrated solution protein solution, sodium stearate and glycerol gas+gas washing gas, soluble gas and insoluble gas respectively, and CO2(HCl) was introduced and shortened, liquefied with different boiling points, and the U-shaped tube was separated by ordinary ice water NO2(N2O4)i, evaporation and crystallization evaporation. 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. Two. 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 should be paid to the 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.
Three. Liquid separation and extraction liquid separation are two 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. Attention should be paid in the extraction process: ① Pour the solution to be extracted and the extraction solvent into the separation funnel from the upper opening in turn, and the dosage should not exceed 2/3 of the funnel volume, plug the plug and shake it.
(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. Four. 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. 2. Separation of purified substances by chemical methods Generally, substances can be treated by chemical methods first, and then separated by appropriate separation methods according to the characteristics of the mixture (see basic operation of chemistry).
Attention should be paid to the separation and purification of substances by chemical methods: ① It is best not to introduce new impurities; ② The quality of the purified substance should not 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.
The following methods are commonly used in the separation and purification of inorganic solutions: (1) generation precipitation method (2) gas generation 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, removal of common substances, serial number, removal of impurities contained in original substances, main operation methods,1. Gas 2co2H2SO4 solution washing gas 3co2NaOH solution washing gas 4coCO combustion CuO washing gas and solid conversion gas 5 coh cl saturated NaHCO3 washing gas 6 H2S HCl 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 concentrated hydrochloric acid (heating is required) filtration 1 1mo2C- heating combustion 12 carbon powder CuO diluted acid (such as dilute hydrochloric acid) filtration 1 3al2o3 NaOH (excessive), CO2 filtration/CO2 filtration. 4 fe2o 3 al2o 3 NaOH solution filtration 15 al2o 3 SiO 2 hydrochloric acid `ammonia water filtration 655438Fe and Cl2 filtration 22 FeCI2 solution FeCI3 Fe and reductant conversion method 23 CuO Fe (magnet) adsorption 24 Fe(OH)3 colloidal FeCl 3 distilled water dialysis 25 CuS FeS dilute hydrochloric acid filtration 26 I2 crystallization NaC.