除杂（Impurity）

除杂（Impurity） 除杂(Impurity) Topics on impurity removal A method of purifying substances. The object is to remove impurities from the mixture to obtain a purer substance. Principle: 1 to remove impurities, and no new impurity is introduced, and the retention of composition and impurity formation easy separation The main component of chemical reaction can occur Commonly used methods of removing impurities: physical method (mainly for filtration); chemical method. The five commonly used methods of removing impurities with chemical principles are given as follows: 1. Convert impurities into precipitation and remove them. (1) hydrochloric acid or soluble hydrochloric acid reacts with silver nitrate to form silver chloride precipitate. Example 1: how do I remove a small amount of sodium chloride from sodium nitrate?. The AgNO3 solution is dropped gradually until the precipitate is no longer generated, and the purified sodium nitrate can be obtained by filtering and evaporating the filtrate. NaClAgNO3 = AgClNaNO3 Sulfuric acid or soluble sulfate reacts with the solution containing barium ion to form barium sulfate precipitation. Example 2: how to remove some of the sulfuric acid mixed with hydrochloric acid?. A BaCl2 solution is added to the mixture in such a way that no precipitation occurs, and pure hydrochloric acid is obtained by filtration. Similarly, the mixture is mixed with soluble carbonate and barium ion (or calcium) solution reaction of barium carbonate (or calcium carbonate) precipitation (also available acid removed CO32); mixture mixed in some soluble salts or copper salts should react with soluble alkali hydroxide or iron hydroxide generated and removed. 2 change impurities into gases and remove them. The common reactions in junior high school chemistry are: carbonate reacts with acids to form carbon dioxide gas. The acid in the selected acid is the same as the acid in the retained substance. Example 3. How can I remove sodium carbonate from sodium chloride?. Add some hydrochloric acid to the solution so that no more bubbles appear, and then evaporate the crystals, which is NaCl. Na2CO32HCl = 2NaClH2OCO2 3. Convert impurities into water and remove them. Example 4. How do I remove the NaOH in NaNO3?. Add some amount of dilute nitric acid to the solution, and then evaporate and crystallize to get sodium nitrate. NaOH+HNO3 = NaNO3H2O 4 remove insoluble impurities into soluble substances. Example 5. How to remove iron powder from copper powder?. Add dilute hydrochloric acid (or dilute sulfuric acid) to the mixture until it does not produce bubbles, and then wash the solution to obtain copper (and also add soluble copper salts to the mixture to remove iron). Fe2HCl = FeCl2H2 or FeH2SO4 = FeSO4H2 or FeCuSO4 = FeSO4Cu 5 change impurities into retained constituents. Example 6. How do you remove carbon monoxide gas from carbon dioxide gas?. Analysis: carbon monoxide is reducible, while carbon dioxide does not. Carbon monoxide is converted from carbon monoxide to carbon dioxide by reacting a mixture of gases through a glowing copper oxide. COCuO Elimination of common substances Gas removal: (impurities in brackets) 1.CO2 (including O2): pass gas through a hot copper net. 2.CO2 (containing H2 or CO): pass the gas through the glowing copper oxide. 3.O2 or CO2 or H2 (including H2O): passing gases through concentrated sulfuric acid or calcium oxide or calcium chloride and other drying agents. 4.O2 or H2 or CO (containing CO2 or SO2): the gas is passed into the sodium hydroxide solution Two solid impurity removal: 1.Cu (containing Fe or Mg or Zn): add sufficient dilute hydrochloric acid or dilute sulfuric acid to filter. Dissolve active metals with acids 2.Fe (including Cu): magnet is used to attract iron powder. 3.Cu (containing CuO) and Fe (including Fe2O3): react with H2 or CO at high temperature. (reduce metal oxides into metals) 4.CuO (containing Cu or C): burns in the air. 5.CaO (including CaCO3): high temperature calcination (CaCO3 decomposition into CaO and CO2) 6.CaCO3 (including CaO): dissolved in sufficient water, filtered and removed. (CaO reacts with water and dissolves in water) Seven CaCO3 (including CaCl2): dissolved in sufficient water, filtered and removed. (CaCl2 soluble in water, CaCO3 insoluble in water) 8.CaCl2 (including CaCO3): dissolved in sufficient water, filtered, and filtered to evaporate. 9.Ca (OH) 2 (including CaO): add plenty of water. (CaO reacts with water to form calcium hydroxide) Three. Removal of impurities by solution: 1.FeSO4 solution (containing H2SO4 or CuSO4), FeCl2 solution (containing hydrochloric acid or CuCl2): Add excessive iron powder, filter, take filtrate. The reaction: Fe+H2SO4=FeSO4+H2 = Fe+CuSO4=Cu+; FeSO4 Fe+2HCl=FeCl2+H2 = Fe+CuCl2=Cu+; FeCl2 2.NaCl solution (including Na2CO3): add the right amount of dilute hydrochloric acid. = Na2CO3+2HCl=2NaCl+H2O+CO2 3.Na2SO4 solution (containing CuSO4): add a proper amount of NaOH solution. CuSO4+2NaOH=Cu (OH) 2: +Na2SO4 Exercises: 1. the following experimental scheme, feasible is () A. separate the mixture of CaCl2 and CaCO3 in the order of dissolution, filtration, and evaporation B. drops white vinegar on the wet pH test paper and determines its pH C. removes the HCl gas in CO2 with sodium hydroxide solution D. removes a small amount of K2SO4 in KNO3 solution with BaCl2 solution 2. remove the small amount of K2CO3 mixed with KCl solution, and the reagent used is A.H2SO4 solution B. dilute hydrochloric acid C.K2SO4 solution, D., AgNO3 solution 1, A 2, B 3, C 4, A 5, C 6, B 7, D 8, C 9, B 10, C 3. the following removal methods are correct () A. removes some of the mixed HCl in CO2 with NaOH B. removes a small amount of CO in the CO2 by kindling C. water is removed, some KCl MnO2 mixed with D., nitric acid is used to remove NaCl mixed with Na2CO3 4., the removal of a small amount of impurities in the following substances, the reagents and methods used are correct project material Impurities (small quantities) reagent Operation method A KNO3 MnO2 Enough water Dissolve, filter, evaporate B H2 Steam A moderate amount of NaOH solution Gas washing C nitric acid hydrochloric acid Excessive silver nitrate solution filter D CO CO2 Sufficient iron oxide heating 5. the following table lists methods for removing small amounts of impurities contained in the material, wherein the error is () material Impurities contained A method of removing impurities A CO CO2 Dried by adequate sodium hydroxide solution B NaCl Silt Dissolve, filter, evaporate C NaOH solution Na2CO3 Add enough hydrochloric acid to no longer produce bubbles D Cu (NO3) 2 solution AgNO3 Add excess copper powder and filter 6. the removal of small amounts of impurities in the following substances is correct Matter Impurity Impurity removing reagent Purification method A CO2 CO O2 Light B KCl MnO2 water Dissolve, filter, evaporate C H2O NaNO2 Activated carbon Adsorption and filtration D Na2CO3 Na2SO4 BaCl2 Dissolve, filter, wash 7. the following methods of removing impurities are not correct option Substances (impurities in brackets) Impurity removal method A N2 (O2) Through a hot copper net B CaO (CaCO3) High temperature calcination C CO2 (water vapor) By concentrated sulfuric acid D CaCl2 solution (hydrochloric acid) Add proper amount of Na2CO3 8. in the following table, the method of removing impurities contained in the material is correct material Impurities contained A method of removing impurities A NaCl solution NaOH The addition of dilute hydrochloric acid pH equals 7 B CuO powder C Add an excess of dilute hydrochloric acid to give full response C N2 gas O2 Pass the gas slowly through the hot copper net D KCl solution CuCl2 Add sodium hydroxide solution to precipitate 9., the method of removing some small amounts of CO2 in CO is () A. passes through concentrated sulfuric acid B. and passes into sodium hydroxide solution C. ignites the gas mixture, D., through hot iron oxides 10. the following experimental design is not reasonable A.: salt dissolution, filtration, evaporation and purification B. remove the Na2CO3 mixture in the NaOH solution: add an appropriate amount of dilute HCl C. remove the K2CO3 mixture in the KCl solution: add an appropriate amount of dilute HCl D. remove CaCO3 mixed with CaCl2: add water, filter, wash, dry 11. removal of impurities in each of the following substances, the reagents and methods used are correct material impurity Reagents and methods for removing impurities A. CaO solid CaCO3 solid Add the right amount of dilute hydrochloric acid B. NaOH solution Ca (OH) 2 solution First add an excess amount of Na2CO3 solution, then filter C. CO2 gas CO gas Light D. H2 gas HCl gas First through the NaOH solution, and then through concentrated sulfuric acid 12, salt mixed with Mg2+, Cu2+, SO42 and sediment, in order to remove the impurities in the laboratory can be salt dissolved in water and then do the following: 1 the filtration; adding sodium hydroxide solution to excess; by adding hydrochloric acid; the addition of excessive Na2CO3 solution; the adding excessive BaCl2 solution; proper sequence of operation is () A is the first B in the 2, which is C is the first D in the book, the results. 13, a salt solution containing a small amount of CaCl2, MgCl2, Na2SO4 and sediment, the following can be impurity removal, the filtration; the added amount of hydrochloric acid; adding the excessive sodium hydroxide solution; the addition of excessive sodium carbonate solution; adding the barium chloride solution; correct operation sequence is () The A 1 B 1 2 3 4 2 3 4 the The C is the D of the 4 3 2 2 1 14, to get rid of salt containing magnesium chloride, Magnesium Sulfate and other impurities in. We design a impurity solution: put salt solution in water, filtered into clear solution, and then process the following steps: adding barium chloride solution to precipitate completely; using hydrochloric acid to adjust pH to acidic solution; and adding NaOH solution to the complete precipitation; waste filtered precipitation filtration 5; adding sodium carbonate solution to complete precipitation evaporation; finally make the NaOH crystal precipitation, the processing sequence of reasonable arrangement is () A, B C, II. D, II 11, B 12, A 13, A 14, B 15, C 16, A 15, in addition to calcium chloride, Magnesium Sulfate and salt in sediment, salt can be dissolved in water, then the following four operations (and filtering operation) The addition of excess BaCl2 solution the amount of hydrochloric acid, and the excess of Gaga Na2CO3 The addition of excessive NaOH solution following the order belongs to the right (is) A: the B and the 1 2 3 1 2 3 4 C D 1 2 3 4 16, sodium nitrate solution mixed with Mg2+, Ba2+, Ag+ three kinds of metal ions, NaOH, Na2SO4 and NaCl are three kinds of reagents make them precipitated and separated for each reagent, filter out a kind of precipitation, and finally achieve the purpose of removing impurities, the reagent is correct () A, NaCl, Na2SO4, NaOH, B, Na2SO4, NaOH, NaCl C, Na2SO4, NaOH, NaCl, D, NaOH, NaCl, Na2SO4 11, B 12, A 13, A 14, B 15, C 16, A 17. Choose one of the reagents provided to remove a small amount of impurities in the following substances (impurities in brackets), Reagent for selection only: Caustic soda solution; sodium sulfate solution; hydrochloric acid; water (1) fill in the corresponding line of code for the reagent selected. CaC03 powder (Na2C03); H2 (C02) (2) write out the chemical equation for the reaction: 17., C02+2NaOH=Na2C03+H20 (write C02+NaOH = NaHC03 also points) 18. Select appropriate reagents or methods to remove impurities from brackets. (1) CaO (CaCO3); (2) Cu (Fe); (3) NaCl (CuCl2). (4) ZnSO4 (CuSO4) ____________________. (5) O2 (water vapor) _________________________ 18. (1) heating (2) dilute hydrochloric acid (3) sodium hydroxide solution (4) zinc (Zn), (5) concentrated sulfuric acid, [H2SO4 (concentrated), etc. 19. Please answer the following questions relating to the purification of substances: (1) the following two schemes can remove a small amount of copper oxide in copper powder Removal of cupric oxide by dilute hydrochloric acid and reduction of cupric oxide by CO From the consideration of environmental protection and convenient operation, good scheme (optional "1" or "II"); (2) to remove a small amount of KOH in the K2SO4 solution, dilute hydrochloric acid cannot be used because it produces (fill in the name or chemical formula of the specific substance) and introduces new impurities: (3) to make a small amount of Na2 SO4 in NaCl solution into precipitation and remove it, we can choose the right amount, (4) to remove a small amount of water vapor and hydrogen chloride gas in hydrogen, the mixture will pass through a sufficient amount of concentrated sulfuric acid and then pass through a sufficient amount of sodium hydroxide solution 19, (1) (2) potassium chloride (or KCl); (3) barium chloride solution (or BaCI2 solution, barium chloride, BaCl2); (4) water vapor (or water, H2O); . 20, with Na2CO3, BaCl2 (Ba2+ toxic), hydrochloric acid three kinds of drugs, remove the salt contains Na2CO3 and Na2SO4, get pure NaCl solution, then the reasonable order of adding drugs is 20, BaCl2, NaCO3, HCl. 21, existing a pack of NaCl solid in the mix a small amount of sodium sulfate and magnesium chloride, through the following experiments to remove impurities to obtain pure NaCl please order operation will correct in the brackets, and a brief answer to the questions ~ Add a slightly excess amount of Na2CO3 solution to the solution and then filter (add) a slightly excessive amount of BaCl2 solution, and then filter. (NaCl) mixing impurities with water completely dissolved in water. (PH) the addition of dilute hydrochloric acid to the solution is equivalent to 7 (evaporation) crystallization (add a slightly excessive amount of NaOH solution to the filtrate and then filter it 21 and 321564 22, a factory discharged waste water mainly containing zinc sulfate and silver nitrate, in order from the recovery of silver and zinc nitrate, Xinmin middle school chemistry extracurricular activities designed experimental steps The X and Y are what matter? X Y What are the main components of the solid A and B, C of the filtrate? A B C What is the Y of the operation? 22, the X:Zn Y: H2SO4 A:Zn Ag B:Zn (NO3) 2 C:ZnSO4 by evaporation Reference answer: . Six