Removal of impurities Can general impurities be avoided

hcl+naoh=nacl+h2o

The impurity HCl is removed, and the new impurity H2O is brought out, and NaCl is formed and dissolved in solution, not in gaseous form.

Concentrated H2SO4 (water absorption) is introduced to remove H2O

That's right, when the gas passes through the NAOH.

HCl+Naoh==NaCl+H2O (There is no gaseous substance, so doesn't H2 be separated?) )

Isn't it okay to remove the water by removing the water with concentrated sulfuric acid, and it's over?

I can't stand it, NaCl and H2 are mixed together, can't you separate the hydrogen? NaCl dissolves in water, hydrogen is insoluble, it's like a glass of brine in front of you, there is oxygen in the brine cup, how do you separate them? Isn't it just pumping the oxygen away, and the NACL is still in the cup?

Oh, yes! Then the HCl impurity gas can be absorbed! Concentrated sulfuric acid then acts as a drying water

That's right. Questions? It was originally hydrogen, but now it contains HCl impurities, so it is necessary to neutralize HCl with NaOH through the NaOH solution, and then absorb the excess water through H2SO4. What is left is pure hydrogen.

In general, impurities may not be completely avoidable, but the impact of impurities on product quality and food safety can be minimized. Here are some common ways to reduce impurities:

1.Quality Inspection: Strict quality inspection of raw materials and finished products can reduce the possibility of impurities.

2.Cleaning and selection: Proper cleaning and selection of raw materials prior to processing can reduce the amount of impurities.

3.Production environment control: Cleaning, dust removal, disinfection and other treatments on the production environment can reduce the possibility of external impurities entering the production process.

4.Process control: Strict control of temperature, humidity, time and other parameters in the production process helps to reduce the generation and accumulation of impurities.

5.Testing and screening: Detect and screen finished products to detect and isolate impurities in time to improve product quality and ensure food safety.

It is important to note that different types of products may have different requirements for impurities, so the method of reducing impurities may also vary from product to product. For example, in the food processing industry, relevant regulations and standards should be strictly adhered to to ensure the hygienic quality of the products.

CO2 is introduced into the clarified lime water Ca(OH)2 + CO2 = CaCO3 + H2OHCL

By sodium bicarbonate solution HCl+NaHCO3=NaCl+CO2+H2ONa2O

Heat 2Na2O+O2===2Na2O2Al in oxygen

Solution with sodium hydroxide 2Al+ 2NaOH + 2H2O = 2Naalo2+ 3H2

Iron does not react with sodium hydroxide).

Al2O3 can be added with a strong base For example: NaOH : 2NaOH + Al2O3 = 2Naalo2 + H2O

al(oh)3

Add sodium hydroxide solution to Renjiao version: NaOH+Al(OH)3=Na[Al(OH)4].

Fe2O3 was added to dilute hydrochloric acid Fe2O3+6HCl=2FeCl3+3H2OFE(OH)3

Heating: 2Fe(OH)3=Fe2O3+3H2OCL2

By sodium hydroxide solution 2NaOH+Cl2-NaCl+Naclo+H2O powder NaHCO3

Heating 2 NaHCO3 = (conditioned to heat) Na2CO3 + CO2 + H2O solution NaHCO3

Add NaOH solution NaOH + NaHCO3 = Na2CO3 + H2O solution Na2CO3

Pass in the right amount.

Hehe, it took me almost half an hour, which is equivalent to me reviewing.

Thank you for giving me the motivation to review again.

1.To remove carbon dioxide from oxygen, the gas mixture can be passed through a NaOH solution with the ion equation CO2 2OH = CO32 H2O

2.The equation for removing HCl ions from CO2 is: the mixed gas can be passed through a saturated NaHCO3 solution, and HHCO3 = H2O CO2

3.The mixture is heated in oxygen, (ion-free equation).

4.The mixture is added to a sufficient amount of NaOH solution, and its ion equation is: 2AL2OH 2H2O = 2ALO2 3H2

5.Or add to NaOH solution, the ion equation is: Al2O3+2OH-=2alo2-+2H2O

6.With sodium hydroxide solution:ion equation: Al(OH)3 +OH- =ALO2- +2H2O

7.Iron oxide is removed with hydrochloric acid. fe2o3 +6h+ =2fe3+ +3h2o

8.Heat iron hydroxide. 2fe(oh)3=fe2o3 +3h2o

9.Chlorine can react with sodium hydroxide solution. cl2 + 2oh- =cl- +clo- +h2o

10.Sodium bicarbonate solids can be turned into sodium carbonate when heated. 2nahco3==na2co3 +co2 + h2o

11.Add an appropriate amount of sodium hydroxide solution. hco3- +oh- =co32- +h2o

12.Carbon dioxide is introduced. co32- +co2 + h2o ==2hco3-

Sodium hydroxide. Saturated sodium bicarbonate.

Heating in air.

Sodium hydroxide. Sodium hydroxide.

Sodium hydroxide. Hydrochloric acid.

Burn. Sodium hydroxide.

Heating. Sodium hydroxide.

through carbon dioxide.

First add Ba(NO3)2, Ba2+ reacts with CO32- to form BaCO3 precipitate, so that A and C are wrong.

In addition, AG+ can react with Cl-, CO3 2-, and OH-, so AgNO3 should be added at the end and only react with Cl-.

In this way, OH- is removed with mg(NO3)2 and is added before AGNO3.

So 1 is added in front of 3.

In this case, option d is wrong, and you can only choose b

I choose BBecause hydroxide reacts with silver ions and has precipitation.

Option D explanation: First of all, remove the carbonate ions, filter, you know that here is to identify the ions in the removal of impurities is different, and you must be careful not to introduce new impurities. Then, it is to add silver nitrate to remove chloride ions, and if there is 1 magnesium hydroxide here, there is also a precipitation, and it can't be separated, so the result comes out.

The impurity of KCl is CaCl2

Why can it be removed with Na2CO3?

Sodium carbonate should not be used, potassium carbonate and hydrochloric acid should be used.

cacl2k2co3

caco3+2kcl

After filtration, excess hydrochloric acid is added to remove excess potassium carbonate.

k2co32hcl

2kClCO2, pure potassium chloride can be obtained after evaporation.

The impurity of H2 is HCl, why can it be removed with NaOH?

naohhcl

NaClH2O, after drying can give pure H2

The impurity of H2S04 is Hno3, why can it be dissolved with BA(NO3)2 and filtered to remove it?

SO2 is introduced into the solution

3so22hno3

2h2o =

3h2so4

The impurity of 2NO CO is CO2, why can it be removed with NaOH?

2naohco2

na2co3

The impurity of H2OHNO3 is HCL, why can it be removed with AGNO3?

hcl+agno3

agcl↓hno3

The impurity of Cu is Cuo, why can it be used to get out with HCL?

cuo+2hcl

cucl2h2o

1, K2CO3 should be used, CaCO3 can be filtered and removed, leaving KCl2, H2 does not react with NaOH, and HCl reacts with NaOH 3, if the impurity in HNO3 is H2SO4, it can be dissolved with BA(NO3)2, filtered and removed, because BASo4 is a precipitate.

4. Because CO2 is an acidic gas, it will react with NaOH, while CO5 will not produce AgCl precipitate with AG+.

6. Cuo is a basic oxide, which can be reacted with HCl to obtain a solution, and filtration can obtain Cu

Principle: no increase, no decrease, easy to divide, recovery.

Transformation method (conversion of impurities into purified substances).

Removal method (the impurity is transformed to make it different from the state of the purified substance, so as to facilitate separation, so as to achieve the purpose).

The extraction method (precipitating the required substances first, and then adding acid to dissolve and restore) is more familiar with it because I am in the third year of junior high school, hehe.

Physical Method: Filtration method - to separate out insoluble impurities. Such as coarse salt purification.

Distillation: Impurities are separated according to the boiling point of the substance. Such as the fractionation of petroleum.

Chemical method: conversion method (converting impurities into purified substances) removal method (transforming impurities into a different state from the purified substances, so as to facilitate separation, so as to achieve the purpose).

The basic principle of extraction method (precipitating the required substances first, and then adding acid to dissolve and restore) is to remove impurities: no increase, no reduction, easy separation, and recovery.

I checked the method of chemical impurities, the document in this ** is very comprehensive, and there are also topics, I hope to help you!

Depending on the nature, solid-liquid filtration, stratified separation, and evaporation point are not allowed to be distilled.

Excessive HCl is added at high temperature

Re-evaporation crystallization.

Hydrogen reduction. Add water to dissolve.

The principle of material removal is:

No increase, that is, no new impurities can be introduced while removing impurities;

No reduction, that is, the substance to be purified cannot be reduced;

Simple, i.e., the separation operation is simple and easy;

Easy to obtain, that is, impurity removal reagents are cheap and easy to obtain;

Preferably, that is, the method chosen ensures the removal of impurities, and at the same time, it is best to increase the amount of purified substance.

The common methods of removing impurities from substances are as follows:

1. Take advantage of the differences in physical properties.

1.Solubility difference method: If there is a significant difference in solubility between the purified substance and the impurity, the solubility difference method can be used to remove impurities.

2.Crystallization method: If the solubility of each component in a mixture in a solvent changes with temperature, the crystallization method can be used to remove impurities.

3.Extraction and separating method: using the different solubility of solutes in immiscible solvents, one solvent is used to extract the solute from the solution composed of another solvent, and then the separating funnel is used to separate it.

4.Sublimation method: Separate solid substances that can be sublimated from solid substances that cannot be volatile.

5.Magnet method: The magnet can attract iron, and the iron can be separated from other impurities that cannot be attracted to iron or removed from the substances that cannot be attracted to iron.

6.Dialysis: Dialysis is the operation of separating ions or molecules from the colloidal solution by putting a colloid mixed with ionic or molecular impurities into a semi-permeable membrane bag and putting the bag into a solvent to separate ions or molecules from the colloidal solution. Dialysis is mainly used to purify and refine liquid sols.

7.Distillation: The boiling point of substances is different to separate miscible mixtures.

Second, take advantage of the difference in chemical properties.

1.Thermal decomposition method: For solid mixtures with large differences in stability, thermal decomposition method can be used.

2.Redox method: using the oxidation and reduction properties of substances to oxidize or reduce impurities into substances that are easy to separate.

3.Complexation: A complexing agent is added to convert impurities into soluble complexes, making them easily separated from the desired substances.

4.Precipitation method: The impurities in the liquid or gas mixture are converted into precipitate with chemical reagents to remove.

5.Acid-base dissolution method: using the properties of solid impurities to react with acids or alkalis, impurities are converted into soluble salts and removed.

6.Acid and alkali scrubbing method: using the properties of the reaction between impurities and acids or alkalis, the impurities in the gas mixture are transferred to acid solution or alkali solution respectively.