Chemical identification questions, please analyze in detail, organic chemistry identification questi

First, 5 kinds of powders were dissolved in distilled water, and the soluble ones were Al2(SO4)3 and Na2CO3; The insoluble ones are MGO, Al(OH)3 and H2SiO3.

Add NaOH to the dissolved Al2(SO4)3 and Na2CO3, and the precipitate is Al2(SO4)3, and the other is Na2CO3;

Then the insoluble substance is added to NaOH, which dissolves Al(OH)3 and H2SiO3, and another insoluble powder is MGO.

Hydrochloric acid is added to the solution of Al(OH)3 and H2SiO3 (containing AlO2- and SiO3 2-, respectively) to an excessive amount, and the original powder that precipitates and dissolves after the precipitation is Al(Oh)3, and the original powder that does not dissolve the precipitate is H2SiO3.

option B Dissolve 5 kinds of powders with distilled water, and the soluble ones are MGO, Al2(SO4)3 and Na2CO3; Insoluble are Al(OH)3 and H2SiO3.

Add NaOH to the dissolved MGO, Al2(SO4)3 and Na2CO3, there is a precipitate to form MGO, there is a precipitate to form and then disappear is Al2(SO4)3, and the one that has no change is Na2CO3;

The insoluble substance is added to hydrochloric acid, and the dissolved is Al(OH)3, and the other insoluble powder is H2SiO3.

B First of all, you can use water to determine whether it is soluble, the insoluble ones are sodium carbonate, aluminum hydroxide, add NaOH solution, and the original soluble precipitate is magnesium oxide.

The insoluble becomes soluble, and the one with hydrochloric acid and bubbles is sodium carbonate.

4-2-2 with Lucas reagent. The former quickly appears cloudy and stratified, while the latter has no noticeable phenomenon for 1 hour.

4-2-3 I don't know yet. Nitro nature was not studied in high school.

4-3-5 First dissolved in sodium hydroxide solution to obtain chloroform, aniline mixture + sodium benzoate aqueous solution. Separation, the aqueous layer is treated with acid, and benzoic acid is obtained at a lower temperature. The organic layer is treated with acid, and chloroform is produced by separating the liquid, and the aqueous layer is treated with alkali, and aniline is produced by separating the liquid.

Note: 1ml of aniline dissolved in 200ml of water.

422.Fractionation.

423.Fractionation.

435.Dissolve, separate aniline, fractionate, separate benzoic acid and chloroform.

The common chemical reagents that need to be mastered to answer the organic chemistry identification questions are: newly prepared copper hydroxide (Feilin reagent) can be used to identify low-grade aldehydes and reducing sugars, and the phenomenon is to form brick-red precipitates; It can also be used to distinguish monools from polyols, and the phenomenon is that the polyol copper hydroxide dissolves to form a dark blue solution. Silver ammonia solution can be used to identify low-grade aldehydes and reducing sugars, and the phenomenon is the formation of silver mirrors; It can also be used to distinguish between terminal alkynes and non-terminal alkynes, and the phenomenon is that terminal alkynes form white precipitates.

Silver-nitrate alcohol solutions can be used to identify tertiary, ethylene, allylene, and isolated halogenated hydrocarbons, as well as chlorinated, bromo, and iodine hydrocarbons. The phenomenon is that tertiary halogenated hydrocarbons and allyl halogenated hydrocarbons immediately form precipitate; Secondary halogenated hydrocarbons and isolated halogenated hydrocarbons need to be left for a period of time or heated to form a precipitate; Primary halogenated hydrocarbons and ethylene-type halogenated hydrocarbons are difficult or non-existent to precipitate. Chlorinated hydrocarbons produce white precipitates; Brominated hydrocarbons produce yellowish precipitates; Iodogenated hydrocarbons produce yellow precipitates.

2,4-dinitrophenylhydrazine reagent and saturated sodium bisulfite solution can be used to identify aldehydes and ketones (organic compounds containing carbonyl groups), and the phenomenon is that 2,4-dinitrophenylhydrazine produces orange-yellow precipitates, and saturated sodium bisulfite solution produces white crystal precipitates. Lucas reagent is used to identify primary alcohols (lower alcohols with 3-6 carbon atoms), the phenomenon is that the tertiary alcohols immediately appear turbid, the secondary alcohols need to be left for a few minutes or tens of minutes to appear turbid, and the primary alcohols need to be placed for a few hours or heated to appear turbid. Iodine solution and sodium hydroxide solution (iodoform reaction) are used to distinguish methyl alcohol and methyl ketone, and the phenomenon is that methyl alcohol and methyl ketone produce a yellowish precipitate with a special odor.

NaCl solution conducts electricity, so NaCl solution is an electrolyte.

Yes, according to the definition of electrolyte.

Solid NaCl does not conduct electricity, but NaCl is an electrolyte.

Yes, this is true.

In the second sentence, an electrolyte is a substance that conducts electricity in a dissolved or melted state.

All right, as for the reasons according to the definition.

Electrolytes are compounds that conduct electricity when water is dissolved or melted.

The first sentence is incorrect, the definition in the electrolyte book is premised on the premise that it must be a compound, and a mixture is not an electrolyte when it is a solution. So the second sentence is correct. Sodium chloride crystals cannot conduct electricity because they do not have certain ions of their own.

The second sentence is correct. The first sentence is wrong:"NaCl solution is an electrolyte"Regardless of whether the electrolyte should be a non-electrolyte or a compound, then it must be a pure substance, and the solution is a mixture, so it is neither an electrolyte nor a non-electrolyte.

1. Titration reaction equation: HAC + NaOH = NAAC + H2O

2. Measurement point: Calculation of the pH value of the product NaAC: [OH-] = [(KW Ka)C] 1 2

oh-] =10, H+] =10, pH = selection indicator: phenolphthalein;

3. Calculate the mass volume concentration of HAC in the HAC sample

hac = = （mol/l）