How can I tell if I have sulfate ions?

Add BaCl2 to the solution, if there is a precipitate, it means that there are sulfate ions or carbonate ions in the original solution (because barium ions will form a precipitate when they encounter these two ions), and then add hydrochloric acid, if there is no change, it means that there are sulfate ions in the original solution, and if bubbles occur, it means that it is carbonate ions.

Add hydrochloric acid first to eliminate the interference of some easy ions, such as: carbonate ions, silicate ions, sulfite ions, phosphate ions, silver ions, etc.

After adding hydrochloric acid, if there is no precipitation, continue to add barium chloride solution, if you see a white precipitation, it can indicate the existence of sulfate ions, otherwise there are no sulfate ions!

After adding hydrochloric acid, if there is a precipitation, continue to add hydrochloric acid until the maximum value of the precipitation, after filtration, continue to add barium chloride solution in the filtrate, if you see a white precipitate, you can indicate the existence of sulfate ions, otherwise, there are no sulfate ions!

Other methods are generally not reasonable.

For example, the addition of nitric acid may oxidize sulfite to sulfate.

For example, adding barium nitrate first, and then adding hydrochloric acid does not look at it, the reason is that adding barium nitrate may get barium sulfite precipitation, and the precipitation will not disappear after adding hydrochloric acid, because there are nitrate ions in the solution, and after adding hydrochloric acid, it is equivalent to adding nitric acid, and nitric acid can oxidize barium sulfite to barium sulfate.

For example, it is not right to add barium chloride first, because it may be silver chloride precipitation.

There is a precipitate in the barium chloride solution, and the precipitate is insoluble in the addition of dilute nitric acid, which can be proven.

1.Add BA (NO3) 2

Add a sufficient amount of dilute Hno3

White precipitated and insoluble.

BA ions are a primary method for identifying sulfates, but carbonate can cause interference because BaCO3 is also very soluble and precipitates.

In the general identification test, BA(NO3)2 is added to form a precipitate, and the precipitate at this time contains Baso4, BaCO3, and may even have some other precipitates. However, most of the precipitate will be soluble in Hno3 and BaSO4 will not, so the addition of Hno3 can remove these interferences.

Just know one.

Sulfate ion: A particle with two units of negative charge that can exist independently.

Sulfate: a part of the constituent substance, which is negative bivalent and cannot exist independently, and must be composed of a substance together with the positive part.

Sulfate is a kind of particle that exists independently and maintains the chemical properties of a substance; Sulfate is a cluster of charged atoms of ions, sulfate ion: a particle with two units of negative charge that can exist independently. Sulfate:

A part of the constituent substance, which is negative bivalent, cannot exist independently, and must be composed of a substance together with the positive part.

Build process. 1. The sulfate ions dissolved in water are produced due to the dissolution of sulfuric acid or soluble sulfate in water. Sulfuric acid is a strong electrolyte, and when dissolved in water, it will rapidly undergo secondary ionization, producing two hydrogen ions and one sulfate ion (in middle school, it can be considered according to the textbook description, but in fact, its second ionization is about 10%).

2. Sulfite ions will also be produced by oxidation or sulfur trioxide dissolved in water.

3. Sulfur-containing amino acids will also form sulfate after oxidative decomposition, and cysteine metabolism is the main sulfate in the human body.

The above content reference: Encyclopedia - Sulfate.

The difference is that it is called differently.

Sulfate and sulfate ions are different names for the same substance.

Sulfate, also known as sulfate ion, is an inorganic ion, the chemical formula is ion, the S atom is hybridized with sp3, the ion is a tetrahedral structure, the sulfur atom is located in the body center of the tetrahedral, and the 4 oxygen atoms are located at the four vertices of the tetrahedron.

The S O bond bond length is 149pm, which has a large degree of double bond nature. The bond between the 4 oxygen atoms and the sulfur atom is exactly the same. It exists in aqueous solutions of sulfuric acid, sulfate, bisulfate, etc.

Physicochemical properties. 【Ionic structure】Sulfate is a tetrahedral structure formed by the connection of sulfur atoms and four oxygen atoms through covalent bonds, sulfur atoms form bonds in sp3 hybrid orbitals, sulfur atoms are located in the center of the tetrahedron, and four oxygen atoms are located at its four vertices, and the bond angle of a group of S o S bonds is 109°28', the bond length of the s o bond is.

Because sulfate gets two electrons to form a stable structure, it is negatively charged, and it is easy to combine with metal ions or ammonium to produce ionic bonds and stabilize.

The structure of sulfate ions is variously stated. According to P503-505, Volume II of Inorganic Chemistry (Fourth Edition) published by Higher Education Press, "SO ions have a regular tetrahedral structure, in which the S O bond length is 149pm, which has a large degree of double bond properties. The bond between the 4 oxygen atoms and the sulfur atom is exactly the same.

Sulfate decomposes into sulfur dioxide and oxygen when exposed to high temperatures. Therefore, the total sulfur content of coal must be determined before combustion to reduce the emission of harmful gases.

Generally, sulfates are easily soluble in water. Silver sulfate is slightly soluble, alkaline earth metals (except BE, MG) and lead are slightly soluble in sulfate. Soluble sulfate crystals precipitated from solution often carry crystalline water, such as CuSO·5HO, Feso·7HO, etc.

With the exception of alkali metals and alkaline earth metals, other sulfates have varying degrees of hydrolysis.

The above content reference: Encyclopedia - Sulfate.

Problem 1: Two methods to test sulfate ions In case the solution contains ag ions, direct dilute HCl will also produce white precipitate. Therefore, the best way to test sulfate ions is to add excess BaNo3 first, followed by dilute Hno3

Question 2: How to detect sulfate ions and chloride ions at the same time Excessive barium nitrate solution is added to the sample, resulting in white precipitation, and dilute nitric acid precipitation is insoluble, which can indicate that it contains sulfate. Filter out these precipitates, as they have been acidified with dilute nitric acid, and silver nitrate solutions can be added directly to produce a white precipitate again, indicating chloride ions.

Question 3: How to test sulfate ions, specific steps should be taken The 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.

Question 4: How to test sulfate ions in the laboratory First add a dilute hydrochloric acid solution to exclude the influence of carbonate, and then add a solution with divalent barium ions. The presence of a white precipitate indicates the presence of sulfate ions.

Add barium chloride to precipitate, add hydrochloric acid to precipitate and dissolve and produce gas, the gas is passed into the magenta solution, and the magenta fades, which can prove the presence of sulfite in the solution.

Add BaCl2 solution dropwise to produce a precipitate:

ba₂+ so₂²⁻baso₃↓

ba²+ so₄²⁻baso₄↓

Dilute hydrochloric acid is added dropwise to precipitate and dissolve the original solution with SO and the insoluble original solution with SO

baso₃+ 2h + ba₂⁺+h₂o + so₂↑<

Because the acids commonly used in general laboratories are the three strong acids, hydrochloric acid, sulfuric acid, and nitric acid when testing sulfate, adding sulfuric acid is definitely not good, and when adding nitric acid, sulfite will be oxidized into sulfate ions, so hydrochloric acid should be used.

Other acids, inorganic, non-strongly oxidizing acids are also OK (and there is no ionization of sulfate ions) The requirements of acids are no strong oxidation, no sulfate, no ionization and barium ions to produce white precipitated acids, such as acetic acid.

Because the sulfate is generally tested with Ba2+, the addition of hydrochloric acid can eliminate the interference of carbonate and Ag+.

Other acids do not have this function, because the acidified acid must have Cl-, (Ag2SO4 is also insoluble in acids, and the interference of Ag+ should be excluded).

The main thing is to exclude the interference of anions, because AGCL is intolerant of all acids, and most of the other precipitates can be dissolved in acids. Therefore, hydrochloric acid is chosen, which has both acid ions and chloride ions.

Nitric acid has strong oxidizing properties, of course, sulfuric acid can not be used for the detection of sulfate, adding hydrochloric acid for acidification, can exclude silver ions (through chloride ions) carbonate bicarbonate (through hydrogen ions). Barium chloride is usually used to test sulfate, and if sulfite is present in the solution, the addition of nitric acid will oxidize it to sulfate, which will affect the test. So in summary, hydrochloric acid should be used.

The cl- ions in hydrochloric acid can exclude the interference of silver ions, carbonate ions and sulfite ions, while in the case of nitric acid, due to the strong oxidizing property of nitric acid, the sulfite ions will be oxidized to sulfate ions, and the interference cannot be completely eliminated.

Hydrochloric acid can exclude AG+, carbonate, sulfite, and other acids.

Nitric acid is oxidizing, and if there is sulfite in the original solution, it will be oxidized by nitric acid to sulfate. Needless to say, sulfuric acid, so that the only strong acid left is hydrochloric acid.