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Anonymous users2024-02-10List of organic impurity removal methods (impurities in parentheses).
1. Gaseous alkanes (gaseous alkenes, alkynes).
Impurity removal reagent: bromine water, concentrated bromine water, carbon tetrachloride solution of bromine Operation: washing gas.
Note: Acidic potassium permanganate solution is not available.
Principle: The unsaturated double and triple bonds in gaseous alkenes and alkynes can react with the above-mentioned impurity removal reagents to generate non-volatile bromoalkanes.
2. Separation of gasoline, kerosene and diesel fuel (to put it bluntly, it is the fractionation of petroleum) Impurity removal reagent: physical method Operation: fractionation.
Principle: The boiling point range of each petroleum product is different.
3. Ethylene (CO2, SO2, H2O, trace ethanol vapor) Impurity removal reagent: NaOH solution - concentrated sulfuric acid Operation: washing gas.
Principle: CO2 and SO2 can be removed by reacting with NaOH to form salts, and the water in the ethanol vapor NaOH solution is dissolved and removed, and the remaining water vapor can be absorbed by concentrated sulfuric acid.
4. Acetylene (H2S, PH3, H2O) Impurity removal reagent: CuSO4 solution - concentrated sulfuric acid Operation: washing gas.
Principle: H2S and pH3 can react with CuSO4 solution to produce insoluble matter and be removed, and the remaining water vapor can be absorbed by concentrated sulfuric acid.
5. Separation of methane, chloromethane, dichloromethane, chloroform, tetrachloroform Reagent: physical method Operation: fractionation.
Principle: The boiling point is different.
6. Bromobenzene (BR2).
Impurity removal reagent: NaOH solution Operation: Dispensing.
Principle: Br2 can react with NaOH solution to form salt, which is a strong polar ionic compound, insoluble in benzene but soluble in water (similar compatibility principle).
7. Nitrobenzene (Hno3, water) Impurity removal reagent: water, Operation: dispensing.
Principle: It is equivalent to extracting nitric acid from nitrobenzene with water, and the specific principle is "extraction". The same operation can be used for TNT and picric acid impurities.
8. Gaseous halogenated hydrocarbons (hydrogen halide) impurity removal reagent: water.
Operation: Wash gas (with anti-sucking device).
Principle: Hydrogen halide is soluble in water and can be absorbed by water, while gaseous halogenated hydrocarbons are insoluble in water.
9. Ethanol (water or aqueous solution) Impurity removal reagent: CAO, soda lime Operation: distillation.
Principle: CaO reacts with water to produce non-volatile Ca(OH)2, so only anhydrous ethanol is distilled.
10. Benzene (phenol).
Impurity removal reagent: NaOH solution Operation: Dispensing.
Principle: Phenol can react with NaOH solution to form sodium phenol, which is a strong polar ionic compound, insoluble in benzene and soluble in water (similar compatibility principle).
11. Ethyl acetate (ethanol, acetic acid, water) Impurity removal reagent: concentrated sulfuric acid + saturated Na2CO3 solution Operation: distillation + separation.
Principle: Acetic acid and ethanol undergo a reversible esterification reaction to produce ethyl acetate and water, which coexist in the reaction vessel. Due to the presence of concentrated sulfuric acid in the catalyst, water and ethanol will not be evaporated out of the system, at this time, acetic acid and ethyl acetate are evaporated out of the system at the same time, and condensed and dripped into a container containing saturated sodium carbonate solution, acetic acid reacts with sodium carbonate to form sodium acetate soluble in water and insoluble in ethyl acetate, thus separating from ethyl acetate.
Principle of dispensing: the density of the two is unequal, and they are not miscible with each other.
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Anonymous users2024-02-09This problem is a bit wide, mainly for the removal of soluble impurities in the purification of coarse salt, including magnesium ions, calcium ions and sulfate ions, and other problems can generally be solved according to the idea of this topic. The main thing is to see what the impurities are contained, find out the corresponding reagent bar magazine to remove, and at the same time pay attention to the principle of removing impurities: no increase or decrease is easy to separate.
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Anonymous users2024-02-08Concentrated sulfuric acid is removed from water, water absorbs SO2, and clarified lime water absorbs. co2
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Anonymous users2024-02-07A lot, this one needs to be accumulated on a regular basis.
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Anonymous users2024-02-06Calcium ions are generally replaced by calcium carbonate, and sodium carbonate is selected in order not to introduce new impurity ions.
Magnesium ions have magnesium carbonate precipitation and magnesium hydroxide precipitation, but there is a fact that adding hydroxide ions to magnesium carbonate will transform into magnesium hydroxide precipitation, so magnesium hydroxide precipitation is more insoluble, so magnesium hydroxide is used to remove magnesium ions. Similarly, no impurity ions are introduced, and sodium hydroxide is generally added.
In fact, coarse salt also contains a large amount of sulfate ions, which are removed by adding barium chloride.
During the addition of reagents, in order to ensure complete removal of these ions, the reagent must be added in excess.
After the above 3 reagents are added, there will be excessive barium ions, carbonate ions, and sodium hydroxide ions.
The trouble is the barium ion, the excess barium ion must be removed with sodium carbonate, so when adding the reagent, the barium chloride must be placed before the sodium carbonate, and the rest of the order can be changed, the last step is hydrochloric acid, removing the carbonate ion and hydroxide ion, you know.
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Anonymous users2024-02-05To remove impurities, it is not only necessary to react it, but also to consider whether the product is separated after the reaction.
After hexene bromination, the product dibromohexane is still soluble in hexane, so how to separate it again? It's getting more complicated.
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Anonymous users2024-02-04NO2 in addition to NO2 in NO: over water; 3NO2 + H20 = 2HNO3 + NO in addition to Al2O3 in SiO2 solids: hydrochloric acid filtration, AL2O3 + 6HCl = 2ALCL3 + 3H2O
In addition to NaHCO3 in Na2CO3 solution: add an appropriate amount of NaOH, NaOH + NaHCO3 = Na2CO3 + H2O
In addition to NaCl in aqueous solution, I2 was extracted with Ccl4.
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Anonymous users2024-02-031. Absorption of 4NaOH + 3NO2 = 2Na2NO3 + NO+2H2O through sodium hydroxide solution 2. Sodium hydroxide is added to silica, and alumina is not reacted to generate sodium metaaluminate, dissolved and filtered 2NaOH + Al2O3 = 2Naalo2 + H2O, 3 Heated: 2NaHCO3 = Na2CO3 + H2O + CO2 4 Carbon tetrachloride is added to extract iodine and dissolved in carbon tetrachloride.
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Anonymous users2024-02-02into the water.
Heat with hydrochloric acid.
What is 12.
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Anonymous users2024-02-01H2S is mixed with HCl-saturated NaHS
SO2 is mixed with HCl-saturated NaHSO3
CO2 is mixed with SO2-saturated NaHCO3
Cl2 is mixed with HCl-saturated Naclo
The principle is that impurities can be fully consumed, and it is best to generate the target gas through the impurity removal reaction.
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Anonymous users2024-01-311. MgCO3 + 2HCl hydrochloride can be added == MGCl2 + H2O + CO2
2. Add iron powder Fe + Cu2+ == Fe2+ +Cu3, and immerse in concentrated NaOH solution 2AL + 2NaOH + 2H2O == 2Naalo2 + 3H2
4. Add H2O2 (preferably acidify first) H2O2 + 2Fe2+ +2H+ == 2Fe3+ +2H2O
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Anonymous users2024-01-30MgCl2 (MgCO3) plus hydrochloric acid.
FeCl2 solution (CuCl2) with iron element.
Fe(Al) Add sodium hydroxide solution, FeCl3 solution (FeCl2) plus hydrogen peroxide.
It reacts with HCl and Cu does not react with HCl, so Cu2 is obtained by filtering after adding dilute HClAdd an appropriate amount of dilute HCl, and react sodium carbonate with hydrochloric acid to form sodium chloride. >>>More
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