How to test sulfite ions in sulfate? It is necessary to follow the route of removing sulfate ions i

When judging sulfate and sulfite, if dilute nitric acid is used, barium sulfite precipitation often occurs insoluble in dilute nitric acid, because nitric acid is a strong oxidant, which will oxidize barium sulfite to barium sulfate, thereby interfering with the detection of sulfate ions.

3baso3 + 2hno3 = 3baso4 + 2no + h2o

Therefore, if the tested solution contains sulfite ions, barium chloride solution and hydrochloric acid must be used to test the existence of sulfate ions, but barium nitrate solution and dilute nitric acid cannot be used.

The detection of sulfate ions is the most complex and has many interferences (chloride ions, carbonates, sulfites, etc., the most insidious of which is sulfite). Add quantitative HCl first, (nitric acid can not be added, sulfite will be oxidized to sulfate) to see if there is a precipitation (remove the ag ion and the acid ion interference that can generate gas), if there is no precipitation, then add BaCl2 solution (can not add barium nitrate), if there is a white precipitate generated, there are sulfate ions.

Sulfite ions: Quantitative HCl is added to pass the resulting gas into magenta, and if it fades, it contains sulfite ions. Clarified lime water should not be used, as carbon dioxide can also make it cloudy.

1. When testing sulfate ions, hydrochloric acid is usually used to acidify the experimental environment to eliminate the interference of carbonate, and then soluble barium salts, such as barium chloride, are added to determine whether the liquid contains sulfate ions. Because sulfate with barium metal.

The ionic combination produces barium sulfate.

White precipitate, but there are many insoluble barium salts that are also white, but they are mostly soluble in acids, whereas barium sulfate is insoluble in acids.

2. The commonly used reagents for the detection of sulfate ions are BaCl2 solution and dilute hydrochloric acid.

3. Process: first take a small amount of liquid, acidify it with dilute hydrochloric acid, and then drop in a few drops of BaCl2 solution, and there is a white precipitate, which proves that there is SO?2?。

4. Equations.

ba2?+so?2?=baso?↓，ba2?+co?2?=baco?↓。

Hydrochloric acid is added to the sulfate ion test to prevent sulfite ion interference.

The reason why nitroacid cannot be used to remove impurities with nitric acid is that nitric acid can oxidize sulfite ions to make sulfate ions, so as to interfere with the test. The essence of chloride ion detection is to use Cl- to react with Ag+ to form Huaibei AGCL white insoluble matter (the insoluble substance is also insoluble in nitric acid), if the ion to be tested is carbonate plasma, it can also react with silver ions to form white insoluble matter, but these insoluble substances can react with nitric acid, that is, nitric acid plays a role in avoiding the interference of lead collapse and other particles.

Sulfate Chemical Formula:

Sulfate can also be referred to as sulfate ion with the chemical formula SO. In the so ion, the S atom is hybridized with sp3, the ion has a tetrahedral structure, the sulfur atom is located in the center of the tetrahedral, and the four oxygen atoms are located at the four vertices of the tetrahedron. Sulfate is found in solid and aqueous solutions such as aqueous solution, sulfate and bisulfate.

First method:

Add barium nitrate solution to produce a white precipitate, and then add dilute nitric acid, the precipitate is insoluble, and it can be determined that it contains sulfate ions.

The second method:

Sulfate ion test.

1 Reaction principle: Ba2+

so42－＝baso4↓

2 Reagents used: dilute hydrochloric acid and BaCl2 solution.

3 Dropwise addition sequence: add dilute hydrochloric acid first (to rule out the interference of carbonate and silver ions), and then add BaCl2 solution.

The first method is to exclude the influence of carbonate ions.

The second is to exclude the influence of silver ions.

Chemical experiments Chloride and sulfate ions.

The method is as follows: 1. Add barium chloride dropwise, there will be precipitation generation, and then add hydrochloric acid to the mountain cavity, if there is a phenomenon of precipitation dissolution, it contains sulfite ions.

2. Add dilute sulfuric acid to produce gas, pass the gas into the magenta solution to see if it fades, if it fades, reheat the faded solution, if the colorless solution turns red, it means that there are sulfite ions in the sample.

Sulfite shed is not an oxynate and contains chain vena sulfite ions. Its anhydride is sulfur dioxide. Sulfites are usually absent in surface waters.

If sulfites are discharged into the effluent** municipal effluent, then it can easily oxidize to sulfates. Sodium sulfite, the most common form of sulfite, is an excellent reducing agent used to scavenge oxygen.