Chemicalknowledgeinductiontheoreticalpart

1、Chemical knowledge induction 2 (theoretical part)Two. Theoretical partThe application of law to the hydrolysis of salts:Salt ion with water out of the ionization of hydrogen ions or hydroxyl ions generated weak electrolyte reaction is called hydrolysis of salts.Its general rule is: who is weak, who

2、hydrolysis, who is stronger than others; the two is not hydrolyzed; the two weak is more hydrolysis; the weaker the more hydrolysis.So, in what cases do you consider the hydrolysis of salt?1. to analyze and judge the acidity and alkalinity of salt solution, we should consider hydrolysis.2. the hydro

3、lysis of salt should be taken into account when determining the species and concentration of ions in the salt solution.Such as Na2S solution contains ions, according to the concentration from large to small order:C (na+), >c (s2-), >c (oh-), >c (hs-), >c (h+)Or: C (na+), +c (h+), =2c (s2

4、-), +c (hs-), +c (oh-)when3. the hydrolysis of salt shall be taken into consideration preparing certain salt solutionsSuch as the preparation of FeCl3, SnCl4, Na2SiO3and other salt solution, they should be dissolved in the corresponding acid or alkali solution.4. hydrolysis should be considered when

5、preparing certain saltsAl2S3, MGS,Mg3N2and other substances are very easy to interact with water. They can not exist stably in solution. Therefore, they can not be prepared by the method of double decomposition reaction, but can only be prepared by dry process.5. certain reactive metals react with s

6、trongly acid weak bases and consider hydrolysisReactive metals such as Mg, Al, Zn, etc. react with NH4Cl, CuSO4, AlCl3 and other solutions3mg+2alcl3 +6h2o=3mgcl2+2al (OH): +3h2 = 36. to determine the acidity and basicity of the solution at the end of the neutralization titration, to select the indic

7、ator and to judge the excess of the acid or base in the ph=7, the hydrolysis of the salt shall be taken into accountIf CH3COOaHnd NaOHreact exactly when ph>7, if the two is ph=7 after reaction, then CH3COOH is excessive.The general principle of indicator selection is that the range of discolorati

8、on of the selected indicator should be consistent with the range of pH values of the salt solution obtained after titration. The strong and weak interaction should choose drops of methyl orange; weak acid and alkali drops of phenolphthalein should choose each other.7. preparation of ferric hydroxide

9、 colloid to consider when hydrolysis.Fecl3+3h2o=fe (OH) 3 (colloidal) +3hcl8. hydrolysis should be considered whenanalyzing the reaction between salt and salt.The reaction of two salt solutions should be considered in three steps:(1) redox reactions occur;(2) whether double hydrolysis reaction can o

10、ccur;(3) the above two reactions do not occur, and then consider the possibility of metathesis9. when heating, evaporating and concentrating the salt solution, the hydrolysis of the salt shall be taken into account in determining the final residue(1) whenheating and concentrating non hydrolytic salt

11、 solution, the raw material is usually obtained(2) heating concentrated Na2CO3type salt solution, usually get the raw material(3) heating and concentrating the FeCl3 type salt solution.Finally, a mixture of FeCl3 and Fe (OH) 3 was obtained, and the Fe2O3 was burned.(4) no solid can be obtained when

12、heated, evaporated, dried (NH4), 2CO3 or NH4HCO3 salts(5) Ca (HCO3) heating dry salt solution type 2, the corresponding normal salt.(6) heating Mg (HCO3) 2, MgCO3solution, and finally obtaining Mg (OH) 2 solid10. other aspects(1) the choice of water purifying agent: such as al3+, FeCl3, etc., can be

13、 used as water purifying agent, should be explained from the angle of hydrolysis.(2) the use of fertilizer shall be considered hydrolysis. Such as plant ash can not be mixed with ammoniumnitrogen fertilizer.(3) sodium bicarbonate tablets can treat excessive gastric acid.(4) soda liquid can be used t

14、o wash oil pollution.(5) grinding reagent bottles can not contain Na2SiO3, Na2CO3 and other reagentsAll this is not a lift. In the study, we should analyze the concrete situation and apply it flexibly.Complete flame reaction:1. sodium ion:Sodium flame reaction should not be difficult to do this, but

15、the most troublesome to do. Because sodium flame is yellow, and the alcohol lamp flame for lamp wick is not clean, impure alcohol most of the flame is yellow. Even the near colorless (pale blue) flames, a new wire (or nickel wire, platinum wire) on the ignition, the beginning of the flame is yellow,

16、 it is difficult to explain the flame is the sodium ion or the original alcohol lamp flame. To see the yellow flame of sodium clearly, the following method can be used.The method (tweezers cotton alcohol method): use tweezers to take a small group of cotton (cotton,A little alcohol (95% ethanol, the

17、 same below) is used to squeeze the alcohol out of the cotton and ignite with some sodium chloride or anhydrous sodium carbonate powder.The method (two wire method): 1 a thin wire, one end with sandpaper to wipe, then burning alcohol to a yellow flame flame, using the wire end with water, then dip s

18、ome sodium chloride or sodium carbonate anhydrous powder, and lit a newalcohol lamp (lamp wick clean and pure alcohol), the sodium salt powder with iron wire is placed on the tip of the outer flame burning, then the flame on the tip of a small yellow flame, the flame is sodium.The above experimental

19、 demonstration of the practice of teachers is easy to do, but because the majority of students in experimental alcohol lamp is not clean and it is difficult to see the flame tip, can be changed to the following approach: stained with sodium iron wire is placed on the outer flame any one of a blue fl

20、ame burn, yellow flame covered the blue flame, you can believe that the flame is yellow sodium flame.2. potassium ion:The method (beaker alcohol method):Take a small spoon of anhydrous sodium carbonate powder (fully grinding) placed in an inverted beaker, add 5 to 6 drops of alcohol, lit, light purp

21、le flame can be seen clearly, if observed a cobalt glass, more clearly see the violet flame.The two method (EPAn alcohol method):Take a spoon of anhydrous sodium carbonate powder into a small dish, add 1 ml of alcohol, ignited, burning with a glass rod to stir, can see the purple flame, the observat

22、ion effect is better by cobalt glass, alcohol fast burn phenomenon is more obvious.The method (three wire - Cotton - water):Take a little sodium carbonate powder into a small evaporation pan, add one or two drop of water into a paste; then a small wire end, wipe, bending a small circle, the circle c

23、lip a small piece of cotton, cotton with a little water, and the watersqueezing, the cotton with the paste of sodium carbonate, put burning the alcohol lamp flame, glass can be seen through the cobalt violet flame obviously.The method (four wire method):Methods of experiment with students of the sam

24、emethod of sodium. The method is less effective than methods one or two and three, but approaches textbooks.The observation of potassium flame, indoor light is not too strong, or pale purple flame potassium is not obvious.3. lithium ion:The method (tweezers - Cotton - alcohol method):Take a bunch of

25、 cotton with tweezers, absorb the alcohol, and squeeze the alcohol out. The cotton is covered with Li2CO3 powder and ignited.The method (two wire method) with the sametwo methods: sodium.4. calcium ion:The method (tweezers - Cotton - alcohol method):The same method of sodium.The two method (beaker a

26、lcohol method):Take a spoon of anhydrous calcium chloride powder fine (to suck a small amount of water, if indeed there is no water to drink, let it in the air for a while on the tide) inverted beaker, add 7 to 8 drops of alcohol, lit. The three method (Yao Shifa): a little containing anhydrous calc

27、ium chloride with stainless steel spoon (ditto) fired in the alcohol lamp flame on.5. strontium ion:Method one or two: the same as lithium carbonate method one or two.6. barium ion:The method (wire - Cotton - water):Take a small amount of barium chloride powder grinding on a small evaporation pan, a

28、dd one or two drops of water into a paste, take a small Tie Si, end of sanded net, bending a small circle, the circle clip a small piece of cotton, cotton sucking the water and squeezed dry, put the cotton with the paste of barium chloride put in, burning alcohol lamp flame at the lower part of the

29、outer flame, you can see a clear yellow green barium flame.The two method (cotton water beaker):With a method similar to a small group of cotton after touching water and squeeze dry paste with barium chloride, placed in an inverted beaker, add seven or eight drops of alcohol, lit. Can compare with c

30、otton + alcohol combustion.7. copper ion:The method (wire - Cotton - water): the samemethod with barium ion.The two method (tweezers cotton alcohol method) with sodium ion method.The three method (beaker alcohol method): method with a potassium ion.The four method (Yao Shifa): three with calcium ion

31、s.The flame flame flame phenomenon to be obvious, like the tail of a comet will see clearly, some salt is salt flame reaction to add a small amount of water to dissolve, when burning ion with the evaporation of water and evaporation into the tail of comet like phenomenon is obvious; and some ions wh

32、en burning more volatile into the comet tail like, do not dissolved in water.I hate the comparison of several historical issues1. the working people of our country will make bronze ware as early as the Shang Dynasty; they will make iron in the late spring and Autumn period; they will make steel in t

33、he late Warring States period.2. during the Western Han Dynasty, iron was found to displace copper from copper salts. It was used in the early days of theSong Dynasty and became a pioneer of hydrometallurgy.In the past 3.1965 years, the Institute of organic chemistry in Shanghai, China, has firstly

34、synthesized a life - producing protein, crystalline bovine insulin, in the world.In the 4.18 century, in 70s, Swedish chemist Scheler and British chemist Priest Lee discovered and made oxygen.At the end of the 5.18 century, French chemist Lavoisier used balance as a tool for chemical research earlie

35、r, and concluded that air was composed of nitrogen and oxygen through experiments.At the end of the 6.19 century, scientists finally found that the air contained inert gases (he, NE, AR, Kr, Xe) in addition to oxygen and nitrogen.7. In the fifth Century BC, Greek philosopher de Mclit and others thou

36、ght that everything was made up of a large number of indivisible particles, and called the particles atoms.In the first half century of the 8.19 century, British scientist Dalton proposed the modern atomic theory.In the 9.19 century, A Vogadero, a scientist from Italy, proposed the concept of molecu

37、les. The study put forward the theory of atomic molecular theory. Since the study of chemical reactions with atom molecular theory, chemistry has become a real science.In 10.1897, British scientists discovered electrons.Rutherford discovered the nucleus in 1911.11. Holland chemist general design and

38、 design invented the universal generator.In the 12.1869 years, Telev, a Russian chemist, proposed the periodic law of elements and designed the first periodic table of elements based on the previous research.13. Holland physicist Fan Dehua first studied the interaction between molecules, so later ge

39、nerations called intermolecular force Fan Dehua force.14. French chemist, Le Le, proposed the principle of chemical equilibrium shift.15. British physicist Ding Daer proposed the scattering of light by colloidal particles, known as the Ding Daer phenomenon.16. Brown, a British physicist, discovered

40、the phenomenon of disorderly movement of colloidal particles known as Brown's motion.17. China is one of the earliest countries in the world to exploit and use oil and natural gas18. In the second Century BC, China mastered the technology of plant fiber paper making. It was one of the four great inventions of our country.19. our country knew the powder in the Tang Dynasty, to the Song Dynasty gunpowder has been used in the war. The chemical equation of black powder explosive reaction