高中化学解题方法与技巧High school chemistry problem solving methods and skills.docx

1、高中化学解题方法与技巧High school chemistry problem solving methods and skills高中化学解题方法与技巧（High school chemistry problem solving methods and skills）I carefully collated documents, documents from the networkI only collect and sort outIn case of errorPlease check it yourself!High school chemistry problem solving

2、method and skill relation methodContinuous reactions for multistep reactionsAlthough every step of the reaction are independent (reaction conditions and equipment may be different), but the product before a reaction is a reaction after the reaction, according to the transfer of the intermediate prod

3、ucts, find out the relation of raw materials and final productsIt is very convenient to calculate by relational formulaAnd the accuracy of the calculation results can be guaranteedWhen looking for a relationship, pay special attention to whether some of the elements in the material are transferred i

4、nto the productAre intermediates involved in raw material?It is impossible to blindly derive the relation according to the conservation of atoms in the initial and the productThe following is a considerable amount of treatment: (1) the loss rate of an element in the compound = the loss rate of the c

5、ompound; the loss rate of the intermediate product = the loss rate of the raw material; and the intermediate product conversion rate = the conversion rate of the raw materialThe common reactions of multistep reactions are as follows: 1. Industrial sulphuric acid: FeS2-2S-2H2SO4; II. Industrial synth

6、etic ammonia: 3C-2N2-4NH3; 3. Industrial nitric acid: N2-2NH3-2HNO3; coke acetylene; 3C-CaC2-C2H2in additionIn some subjects, chemical reaction equations that are not seen in some textbooks are often presentIn the form of information as a solution to certain conditionsAt this point, look patiently f

7、or the transformation between substances or elementsSo as to get the correct relationExercises1, the production of sulfuric acid with pyrite containing FeS280%It is known that the ore has a combustion rate of 95%The conversion rate of SO2 was 90%The absorption rate of SO3 was 98%98% tons of sulphuri

8、c acid, 500 tonsHow many tons of raw ore are needed? How many liters under the condition of the air? (assuming the volume fraction of oxygen in air is 20%)2, industrial production of calcium carbide is to use lime and coke heating in the furnace (3C+CaO=CaC2+CO), assuming that the utilization rate o

9、f raw materials 100%, then 36 tons of coke can produce tons of acetylene?3 、 chromium content in steel sample is about 1.3%The procedure for determining chromium content in steel samples is to dissolve the steel sample under acidic conditions and oxidize the chromium to Cr2O72- ionsThen add the stan

10、dard FeSO4 solution of 20.0mL0.100mol/LRespond adequatelyThe chemical equation is 6Fe2+ Cr2O72-+14H+=6Fe3+2Cr3+7H2O, titrated with an 0.010mol/L standard KMnO4 solution to excess Fe2+The amount of KMnO4 solution required is between 5.0010.00mLCalculate the range of the steel sample(Potassium Permang

11、anate and ionic equation for the reaction of Fe2+: 5Fe2+MnO4-+8H+=5Fe3+Mn2+4H2O)4. To determine the mass fraction of CaCO3 in a limestoneWeigh Wg limestone samplesAdd an excess of 6mol/L hydrochloric acidDissolve it completelyHeat boilingRemove dissolved CO2Then add sufficient quantities of ammonium

12、 oxalate (NH4) C2O4 solution, slowly adding ammonia reduces the acidity of the solution, while the precipitation of calcium oxalate precipitation: C2O42-+Ca2+=CaC2O4 down, filter out CaC2O4, H2SO4: CaC2O4+H2SO4=H2C2O4+CaSO4, dissolved as diluted with distilled water dilute solution to remove V0mL, V

13、1mL, KMnO4 in acid solution titration of amol/L occurs at this time the following reaction: _MnO4-+_H2C2O4+_H+, _Mn2+_CO2 = +_H2O if the end point of titration consumption during amol/L KMnO4V2mL, please KMnO4 the trim ion equation and H2C2O4 reaction, and calculate the mass fraction of CaCO3 in the

14、 sample.5. The reaction of phenol and bromine can be used for the quantitative determination of phenolThe method is as follows: 1. KBrO3-KBr solution 1000mL is prepared by the ratio of material to 1:5The solution reacts completely under acidic conditions to produce 0.05molBr2; the reaction is follow

15、ed by the reaction of the solution with an excess of Br2Reductive unreacted bromide was reduced with KITitrate the iodine produced with the Na2S2O3 standard solutionThe chemical equation for the reaction of Na2S2O3 with I2 is 2Na2S2O3+I2=2NaI+ Na2S4O6; according to the volume of the Na2S2O3 standard

16、 solution consumedThe purity of phenol can be calculatedWeighing 0.2g phenol sampleDissolve in water and dilute to 250mL under certain conditionsTake the solution 10mLThe above KBrO3-KBr solution reacts with the 10mL under acidic conditionsAdd excess KITitrate with 0.1mol/L Na2S2O3 solution to the f

17、inish lineConsume Na2S2O3 solution, 5.2mLCalculate the purity of phenol sample(phenol type 94)Solving methods and skills in high school chemistry - total response equation methodAmong the problems in chemistry calculation in senior high school, there are some types of product categories that vary wi

18、th the amount of reactantsSuch as H2S+O2When O2 is not enoughThe VO2/VH2S is less than or equal to 1/22H2S+O2=2S+2H2O; when O2 is enoughVO2/VH2S is more than or equal to 3/22H2S+3O2=2SO2+2H2O; and when 1/2VO2/VH2S3/2The products of H2S combustion are both S and SO2. It is very complicated and error

19、prone if they are discussed step by step according to each specific reactionAt this point, the total reaction equation can be trimmed by the ratio of the amount of reactant materialThe total response equation is used to judge and calculate directlySimilar reactions include: CO2+NaOH = OH, CO2+Ca (2)

20、, H3PO4+NaOH, H3PO4+NH3, Na2CO3+HCl, Al3+NaOH, AlO2-+H+H2O, Fe+HNO3, etc.ExercisesAt 1 and 20 degrees centigradeMix 40 ml H2S with 50 ml O2 and igniteHow many milliliters of gas are there after reaction? (set the temperature and pressure unchanged)2, the standard conditions of 1.12 liters of CO2 gas

21、 into 100 ml 0.7 mol / liter of caustic soda solution, and then at low temperature vacuum evaporation drying solution, how many grams of solid can get?3, 200mL0.8mol/L hydrochloric acid drops into the 300mL0.4mol/L Na2CO3 solutionAfter complete reactionCalculate the volume of the resulting CO2 in th

22、e standard case4, to 148g concentration of 0.1% clear lime water through CO2 gasGet white precipitate 0.1gIf CO2 takes full advantage ofThe volume of the CO2 gas passed into is ()A.22.4mL B.33.6mL C.44.8mL D.67.2mL5. Absorb NH3 under 11.2L standard with 2mol/LH3PO4 solution 200mLFull actingWhat is t

23、he product? What is the amount of its substance?6, Ag iron reacts exactly with nitric acid with BG nitric acid to form NOIf a:b=1:3The quality of the reduced nitric acid is ()A.ag B.3a/4g C.b/4g D.bg7, in 100 ml 0.1 mol / L AlCl3 solution, into the metal sodium, to be completed after the reaction H2

24、392 ml (superscript case), if the metal sodium surface is not oxidized, can produce precipitation how many grams?8, under standard conditionsA mixture of CO and CO2 is filled with a volume of 22.4L, and a sufficient amount of airtight container is used to initiate a complete reaction with a interrup

25、ted electrical sparkThe following are the correct estimates of the amount of substances and their substances that are present in the container (excluding the volume occupied by the solid material)A. exists, 0.5molNa2CO3,0.25molCO, B. exists, 0.125molO2,1mol, Na2CO3C. exists 0.5molCO, 0.5molNa2CO3, D

26、. exist 0.75molNa2CO3,0.25molCO9. Mix the amolNa2O2 and bmolNaHCO3 solids and heat them to 250 degrees in a closed vesselThe exhaust gas after full reaction (set only when the CO2 and Na2O2 after reaction, other substances that react with Na2O2), if the reaction pressure container is 0Pa, and the solid residue in water solution without gas, then add proper amount of CH4 in the reaction, so that it can be fully burnt. This a/b should satisfy what conditions? Join CH4 in standard condition of the volume is how much?2002 college entrance examination training questions: chemical calculation