Separation of mixtures in nature

Separating pure water, (1) distilled water is prepared by vacuum distillation method, the mineral content of distilled water is very low, the purity is relatively high, and it can meet the needs of most experiments, but the energy consumption is relatively high. (2) Ion exchange resin, ion exchange resin can adsorb most of the minerals and other impurities in water, and the water made by ion exchange resin has high purity and is widely used at present.

To separate minerals, (1) the stupid method is to evaporate the water, but the mineral content in the water is very small, so it needs to evaporate a large amount of water, and the energy consumption is extremely high, so it is not recommended to use. (2) The use of a substance to adsorb minerals, this purpose can also be achieved by using ion exchange resins, which can adsorb most ions.

The current method is air liquefaction, at -83, O2 liquefies, N2 is still gaseous, according to the principle of boiling point.

This is also liquefaction, according to the different boiling points of N2 and O2, -83 removes O2 and then cools to -96 to obtain purer N2

The method of separation and purification is not limited to physical or chemical changes. Changes that remove impurities in the sample or separate the various components in the sample can be used under possible conditions. The commonly used separation and purification methods are as follows:

1.Fractional crystallization. This method is often used to heat the evaporation solution to control the density of the solution and crystallize a part of the solute. After repeated operations, the purpose of separation and purification can be achieved.

2.Step-by-step precipitation method. This method often selects appropriate reagents or adjusts pH to precipitate a certain part of the solution. After repeated operations, the purpose of separation and purification can also be achieved.

3.Selective redox method. Use a suitable oxidant or reducing agent to oxidize or reduce some components in the mixture, and further achieve the purpose of separation and purification.

4.Absorption, adsorption method. Absorb certain components of the mixture with suitable reagents, such as caustic soda to absorb carbon dioxide from the gas mixture.

Or use suitable substances to adsorb some components in the mixture, such as adsorbing certain gases with activated carbon, so as to achieve the purpose of separation and purification.

5.Liquid-liquid solvent extraction. Select appropriate solvents to dissolve and absorb some components in the mixture, so as to achieve the purpose of separation and purification.

6.Distillation. The condensation temperature of the vapor of the mixed solution is controlled, so that the components with different boiling points are condensed and precipitated step by step, so as to achieve the purpose of separation and purification.

7.Chromatography.

Teacher Zong: Shaanxi Province's first provincial high school chemistry backbone teacher and the third teaching expert, the national chemistry competition outstanding counselor, senior middle school chemistry teacher, in the 90s of the last century, has been published in the provincial newspapers and magazines more than 60 articles of chemistry teaching, once taught in Xi'an No. 1 Middle School, Xidian University of Science and Technology High School.

A No, alcohol will be dissolved in water, iodine can not be extracted, carbon tetrachloride should be used b No, water can form an azeotropic solution with ethanol, a small amount of water can not remove C pair, NH4Cl === Heating ==NH3 +HCL potassium chloride is difficult to decompose.

The resulting gas cools and then recombines to NH4Cl, so that option C can be separated

B, where A is not good because alcohol and water are miscible, the solubility of sodium chloride in C changes with temperature is small, and the solubility is relatively small, so evaporation should be used for crystallization, and manganese dioxide in D is insoluble in water.

Answer: A miscible liquid mixture, if the boiling point of the crack is quite different, it can be separated by distillation; The immiscible liquids are usually separated by the separating method

a liquid mixture with different boiling points can be separated by a distillation flask, and the heating temperature can be controlled by the method of distillation, so a is correct;

b immiscible liquid mixtures can be separated by separating the liquid by separating the funnel, so b is correct;

c The liquid mixture that is miscible can be separated by distillation by the different points of the boiling sail, so C is wrong;

d The mixture of water-soluble solids and water-insoluble solids can be dissolved with dissolved and water-soluble solids, the latter is insoluble, filtered to obtain water-soluble solids, and evaporated filtrates to obtain water-soluble solids, so d is correct

Therefore, C

Answer A miscible mixture of liquids, if.

Boiling point. The difference is large, and the separation can be carried out by the square collision method of distillation; Immiscible mixtures of liquids are usually separated by the dispensing method.

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1) Dissolve filtration.

2）bacl2

na2co3

HCL Collapse (1 point each).

Test question analysis: (1) The insoluble solids are removed from the water-soluble solids, so they can be dissolved and filtered to remove impurities, and sodium chloride crystals can be obtained by evaporation crystals; (2) NaCl and Na2

SO4 is soluble in water, and impurities can be removed by precipitation method, and in order to exhaust the impurities, the general precipitant needs to be excessive. Sulfate ions are removed first, followed by excess Na2

CO3 removes excess paracaCl2 from the source

Finally, an appropriate amount of hydrochloric acid with hail oak was used to react off the excess Na2CO3

(1) To remove a small amount of CaCO3 mixed in NaCl solid, water can be added to dissolve first, and then filter to remove CaCO3, and then evaporation and crystallization can obtain sodium chloride, so the answer is: dissolve; Filtration;

2) Na2SO4 can react with BaCl2 to form BaSO4 precipitate, Na2SO4 in NaCl is removed, and BaCl2 is added to remove SO4 first

2-ion, then add Na2CO3 to remove excess BaCl2, and finally remove excess Na2CO3 with HCl to obtain pure sodium chloride, so the answer is: BaCl2; na2co3；hcl．

(1) Filtration.

2) Extraction. 3) Evaporation.

4) Distillation. 5) Pyrolysis.