高中化學(xué)必修1 第四章知識(shí)點(diǎn)（High school chemistry 1 chapter 4 knowledge points）

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1、高中化學(xué)必修1 第四章知識(shí)點(diǎn)（High school chemistry 1 chapter 4 knowledge points） The fourth chapter The first section of silicon In nature, silicon is in the form of silica and silicates, and there is no such thing as silicon The properties of silicon dioxide: high melting point, large hardness and inso

2、luble in water 1. Silica is acidic oxide: can react with alkali or alkaline oxide SiO2 naoh + 2 = Na2SiO3 + H2O The formation of sodium silicate is more viscous, so the glass reagent of the acid solution is not used for the glass, and the rubber plug is used SiO2 + CaO = CaSiO3 Hydrof

3、luoric acid is the only acid that reacts with silicon dioxide SiO2 + 4HF = SiF4 arrow + H2O Hydrofluoric acid can corrode the glass and can be used to sculpt the glass, which can't be used in glass reagent bottles, but plastic bottles. Application of silica: fiber optics, silicon, glass, ha

4、ndicraft (quartz, crystal, agate) The preparation of silicic acid: Na2SiO3 + 2HCl = 2NaCl + H2SiO3 Silicic acid is a white colloidal solid that is insoluble in water and is more acidic than carbonated To the sodium silicate solution, the carbon dioxide is formed in white silicate Na2 sio

5、3 + CO2 + H2O = Na2CO3 + H2SiO3 Silica gel can be desiccant after dehydration The aqueous solution of sodium silicate is called water glass, which can be used as soap filler, wood fire retardant and adhesive. Note: the water glass (i.e., sodium silicate solution) is sensitive to the CO2 rea

6、ction in the air and produces H2SiO3. It should be sealed and preserved Application of silicate: ceramic, glass and cement Simple silicon: properties: metallic black solid with metallic luster, high melting point, high hardness, stable at normal temperature Method: Normal temperature can

7、 react with alkali solution and HF Si + naoh + 2 H2O + 2 = = Na2SiO3 h2 write Si plus 4HF = SiF4 + 2H2 USES: Semiconductor materials, photovoltaic (computer chips, semiconductor transistors,) Section ii the element of enrichment in seawater - chlorine 1. The presence of chlorine: i

8、n nature chlorine exists mainly in sea water, mainly in Cl - form. 2. Physical properties of chlorine gas: a gas with a pungent smell and poisonous yellow and green, It is soluble in water (1:2), low temperature and easy to liquefy when pressurized. 3. Chemical properties of chlorine gas:

9、 A, chlorine gas and metal reactions 2 Na + Cl2 = = 2 NaCl (yellow flame, white smoke) Cu + Cl2 = = CuCl2 (palm yellow smoke, a small amount of water with a green solution, such as a large amount of water in blue) 2 Fe + 3 Cl2 = = 2 FeCl3 (not generating FeCl2) (brown smoke) B, chlorine

10、 gas and nonmetallic reactions H2 + Cl2 = = = 2HCl (white fog) (explosion under light of Cl2 and H2) 2 P + 3Cl2 (a small amount) = = 2 PCl3 (white fog) (white smoke when chlorine and P are lit) 2 P + 5Cl2 (lots) = = 2 PCl5 (white smoke) (combustion: the intense chemical reaction of any g

11、lowing heat is called combustion. Combustion does not have to be oxygen to participate. The nature of combustion is the REDOX reaction.) C, chlorine and water Cl2 + H2O ═ HCl + HClO (Cl2 do both oxidant and reducing agent) Hypochlorous acid (HClO) unary weak acid (acid is weaker than carbon

12、ic acid), strong oxidation (sterilization, disinfection), bleaching, unstable and easy to decompose. 2HClO = = 2HCl + O2 New chlorine water composition (particle) : Cl2, H2O, HClO, H +, Cl -, ClO - Chlorine water composition (particle) : H2O, H +, Cl - Dry chlorine gas is not bleached, a

13、nd the essence of bleaching is HClO in chlorine water. D, the reaction with a base solution Cl2 + 2OH minus = = Cl - + ClO - + H2O (using sodium hydroxide to absorb excess Cl2) The ingredients of bleach, CaCl2 and Ca (ClO) 2 The active ingredient of bleaching powder, Ca (ClO) 2 Bleach

14、ing principle of bleaching powder: the process of producing hypochlorous acid by contact with CO2 in the air. E. Reaction of chlorine gas to other compounds (strong oxidant) : Reductive substances such as Fe2 +, Br -, I -, SO2, SO32 -... The substance can be oxidized by chlorine gas. 2 fecl

15、2 + Cl2 fecl3 = = 2 2 nabr + nacl + Br2 Cl2 = = 2 2 nai + Cl2 nacl + I2 = = 2 H2S + Cl2 = = S + 2 HCL Na2SO3 + H2O + nacl + - H2SO4 Cl2 = = 2 F. Laboratory preparation of chlorine gas Section 3 oxides of sulfur and nitrogen Sulfur: yellow powder, insoluble in water, soluble in a

16、lcohol, soluble in CS2. S and metal react with metal sulfide (such as Cu2S, FeS, etc.) SO2: colorless, pungent and pungent, noxious gas, with a denser than air, easy to liquefy, easy to dissolve in water, 1 volume of water dissolved in 40 volumes of SO2. It's the acid anhydride of H2SO3. SO

17、2 + H2O H2SO3 SO2 + Ca (OH) 2 = CaSO3 + H2O The bleaching of SO2 makes the magenta color fade, the non-oxidized reduction reaction, temporary, can only make the purple litmus test liquid red, cannot make it fade. SO2 can be used to kill bacteria. The weak oxidation of SO2: SO2 + 2H2S = 3S + 2H

18、2O Strong reducibility of SO2: SO2 + Br2 + 2H2O = H2SO4 + 2HBr (discoloration of bromine) SO2 + Cl2 + 2 h2o + 2 = - H2SO4 HCL (SO2 with chlorine water into the colored solution such as magenta - bleaching, or no bleaching) 5SO2 + 2KMnO4 + 2H2O = K2SO4 + 2MnSO4 + 2H2SO4 (not memory) (k

19、nowing that SO2 can discolor the KMnO4 solution, SO32 - with H +, KMnO4 - can't coexist in the solution) SO2 + O2 SO3 SO2 test: apply SO2 to bromine, KMnO4 solution and magenta solution to see if it fades. Remove (SO2 or HCl gas) from CO2 and use saturated NaHCO3 solution Check for CO2 a

20、nd SO2 in the mixture of gases: first through magenta - then through KMnO4 - through magenta - and then pass through to clarify the lime water. SO2 only reacts with Ba (NO3) 2 solution and produces white precipitation. It doesn't react with BaCl2. 3SO2 + 3Ba (NO3) 2 + 2H2O = 3BaSO4 + 4HNO3 + 2

21、NO (the equation does not have to be remembered) Red and brown pungent smell poisonous gas, denser than air, easy to liquefy, easy to dissolve in water The valence of N: -3, 0 + 1 + 2 + 3 + 4 + 5 N2O5 is the anhydride of HNO3, and N2O3 is the anhydride of HNO2, 4 no2 + 2 h2o + O2 = 4 hno

22、3 4 no O2 + 2 h2o + 3 = 4 hno3 The fourth sulfuric acid, nitric acid and ammonia Dilute sulfuric acid with acidity: with acid-base indicator and reactive metal reaction to generate H2, which reacts with metal oxide to form salt and water, The salt reaction produces another acid and salt (th

23、e strong acid weak acid) and neutralizes the base Strong H2SO4 and HNO3 react with metal but not H2. Concentrated sulfuric acid: 1 concentrated sulphuric acid is a colorless oil liquid. Sulfuric acid is a strong acid with high boiling point, which is easy to dissolve in water and can be mix

24、ed with water at any rate. Concentrated sulfuric acid will give off a lot of heat when dissolved in water. 2. It can be used to dry H2, O2, N2, CO, CO2, CH4, SO2, HCl, Cl2, etc., which can not be used to dry NH3, H2S, HI and HBr. Strong oxidizing: metals and nonmetals that can be oxidized.

25、2H2SO4 (thick) + Cu = CuSO4 + 2 h2o + SO2 2H2SO4 (thick) + C = CO2 + 2SO2 + 2H2O (how to test the gas produced, see the previous S section) Nitric acid: 1 instability: (easy to decompose) 4HNO3 = = 4NO2 arrow + 2H2O + O2 arrow Strong oxidation 4HNO3 (thick) + Cu = = Cu (NO3) 2 + 2NO2

26、 8HNO3 (dilute) + 3Cu = = 3Cu (NO3) 2 + 2NO up Under normal temperature (cold) thick H2SO4 or strong HNO3 will make the active metal passivate (such as aluminum and iron), so the iron tank can be used to transport thick H2SO4 or strong HNO3. Ammonia: 1. Physical properties: Ammonia is

27、a colorless, pungent odor. Easily soluble in water (1:700), aqueous solution is called "ammonia water"; Ammonia is easy to liquefy, "liquid ammonia", often made refrigerant. Chemical properties: (1) ammonia is weakly alkaline, unstable and easy to decompose. NH3? H2O = = NH3 write + H2O

28、* ammonia can turn the phenolphthalein red or make the wet red litmus test paper blue. (2) reaction of ammonia and acid (generating corresponding ammonium salt) HCl + NH3 = NH4Cl H2SO4 + 2NH3 = (NH4) 2SO4 NH3 + HNO3 = NH4NO3 3 ammonium salt property: soluble in water, easy to decompose, and ammonia with alkali reaction. Nh4 hco3 = NH3 arrow + H2O + CO2 arrow 4 ammonia laboratory method: heating ammonium salt and alkali mixture 2NH4Cl + Ca (OH) 2 = CaCl2 + 2H2O + 2NH3 up