How to test sulfate ions, methods to test sulfate ions

Detection method and principle of sulfate ion.

Method: According to baso

Insoluble in water and acid, SO can be tested with soluble barium salt solution with dilute nitric acid (or dilute hydrochloric acid).

but when there is impurity interference, the reagent should be carefully selected. (1) When CO interferes, due to BACO

Soluble in both dilute hydrochloric acid and dilute nitric acid, you can choose a soluble barium salt and a dilute acid when selecting reagents. (2) When so

When interfering, due to so

It can be oxidized to SO by HNO

When choosing a reagent, BACL should be chosen

solution with dilute hydrochloric acid, then BaCl

Generate baso with so

precipitate, soluble in dilute hydrochloric acid, thus excludes the use of SO

Interference from inspections. When there is so

When interfering, not only can you not choose any combination of barium salt solution and Hno, but you can't choose Ba(NO

The combination of solution with dilute hydrochloric acid, due to the fact that in the solution Ba (NO

Ionization out of NO and HCl ionization out of H

Equivalent to the presence of HNO in solution

The same will put so

Oxidation to SO and it is not possible to determine whether SO is present in the original solution

Ion. (3) When Ag+ interferes, BA (NO) should be selected because AgCl is also insoluble in dilute acid

solution and dilute nitric acid to test SO

ions, preventing the formation of AGCL precipitates.

Detection method and principle of sulfate ion. Principle: h

Both SO and sulfate are produced when dissolved in water

Baso is available

The insolubility of the so

exists. The reagents used are: soluble barium salts and hydrochloric acid (or dilute nitric acid).

Because barium sulfate is a precipitate.

It can be tested with barium chloride.

For example, barium chloride and copper sulfate.

Add barium chloride solution dropwise to produce a white precipitate, and then add dilute hydrochloric acid dropwise to dissolve, then it contains sulfate ions.

First, take a small amount of liquid, acidify it with dilute hydrochloric acid (dilute nitric acid), and then drop a few drops of BaCl2 solution, and there is a white precipitate, which proves that there is SO42-.

The reagents used to test sulfate ions are BaCl2 solution and dilute hydrochloric acid. The order of addition is to add acid first (to eliminate the interference of CO32-, AG+, SO32-), and then add BACL2 solution, not to add BACL2 solution first, and then add dilute hydrochloric acid, otherwise the interference of AG+ cannot be excluded.

It cannot be acidified with dilute nitric acid, otherwise it will oxidize SO32- to SO42-.

Ba(NO3)2 solution cannot be used, and SO32- will also be oxidized to SO42- in the presence of H+ and NO3-.

Equation: BA2++SO42-=BASO4

The reaction principle of sulfate ion is that barium ions plus sulfate will form a precipitate of barium sulfate, and there are two methods.

Method 1: Add barium nitrate solution dropwise to the solution, and the solution produces a white precipitate, and then add dilute nitric acid to the solution, the white precipitate is insoluble, and the solution contains sulfate ions.

Method 2: Add excessive dilute hydrochloric acid to the solution, and then add barium chloride solution, if the phenomenon is that there is no obvious phenomenon when adding dilute hydrochloric acid solution, and there is a white precipitate after adding barium chloride, there are sulfate ions in the solution.

Note: The reagent used is dilute hydrochloric acid and barium chloride solution, and the dropwise addition sequence is to add dilute hydrochloric acid first, and the effect is to eliminate the interference of carbonate and silver ions, and then add barium chloride solution, the first method is to exclude the influence of carbonate ions, and the second is to exclude the influence of silver ions.

The combination of sulfate with metal barium ions will produce a barium sulfate white precipitate, but there are many insoluble barium salts that are also white, but they are mostly soluble in acids, while barium sulfate is insoluble in acids.

Therefore, when testing sulfate ions, hydrochloric acid is usually used to acidify the experimental environment to eliminate carbonate interference, and then soluble barium salts, such as barium chloride, are added to determine whether the liquid contains sulfate ions. At the same time, it should be noted that hydrochloric acid must be added first, and then barium chloride must be added, otherwise it is easy to be disturbed by silver ions, resulting in white precipitate and affecting the inspection.

Therefore, it should: 1) add hydrochloric acid, and then filter out the precipitate;

2) Add barium chloride and observe whether there is a white precipitate.

The barium salt added during the test is best barium chloride, barium nitrate is not good, because hydrogen ions and nitrate ions will have strong oxidation when they meet, which will oxidize sulfite to sulfate, and it is impossible to test whether there is sulfate in the original solution. However, dilute nitric acid should be added dropwise to the generated white precipitate, and if the white precipitate is not dissolved, it is more indicative that it contains sulfate ions.

ba2⁺ +so₄2⁻ =baso₄↓

Ba2 +CO2 = Baco, but because CO2 +2H = HO+Co, carbonate interference can be excluded in an acidic environment.