How to do ion coexistence and the problem of coexistence in alkaline and acidic solutions

1 Under acidic conditions: no hydroxide. There can be no gas that can coexist with hydrogen ions. Swift Fight.

2. The ions that cannot exist under acidic conditions are: weak acid ions and weak acid acid root ions. Reason: strong acid to weak acid. Thiosulfate ions, silver ammonia ions.

3. Some ions can exist alone under acidic conditions, but they cannot coexist under the influence of other ions, because nitrate has strong oxidation and can oxidize ferric.

The above can not coexist in an acidic environment, and the rest can coexist in an acidic environment as long as it produces precipitation, gas and electrolyte in a weak ear with ions in an acidic environment, and no redox reaction can occur.

Acorns that can coexist in large quantities in a strong alkaline solution: In an alkaline solution, this group of ions does not react with each other and can coexist in large quantities

A can not exist in large quantities of Al3+ and Cu2+ in alkaline solution, and combine to form precipitate, so A is wrong;

B can not exist in large quantities of HCO3- in alkaline solution, combined to form water and carbonate ions, so B is wrong;

c In the alkaline solution, the number of mills does not react with each other, and a large number of ions can coexist, so C is correct;

d Mg2+ and NH4+ cannot be present in large quantities in alkaline solution, combined to form precipitate and weak electrolyte, so D is wrong;

Therefore, the ion groups that can coexist in large quantities in a strong alkaline solution are ( )A Na+, NH4+, H+, NO3-B K+, Ca2+, HCO3-, NO3-C Na+, and Mg

The ion groups that can coexist in large quantities in a strong alkaline solution are ( )A Na+, NH4+, H+, NO3-B K+, Ca2+, HCO3-, NO3-C Na+, Mg2+, Cl-, NO3-D Na+, Ba2+, NO3-, Cl-

A NH4+, H+ ions react with hydroxide ions, and cannot coexist in large quantities in solution, so A is wrong;

B Ca2+, HCO3- react with hydroxide ions to form calcium carbonate precipitate, which cannot coexist in large quantities in solution, so B is wrong;

c mg2+ reacts with hydroxide ions to form magnesium hydroxide precipitate, which cannot coexist in large quantities in solution, so c is wrong;

D Na+, Ba2+, NO3-, Cl- ions do not react with each other, and none of them react with hydroxide radicals, and can coexist in large quantities in solution, so D is correct;

Therefore, choose D

a Magnesium ions, ferric ions, nitrate ions, chloride ions.

Divalent iron ions are reducible, while nitric acid is oxidizing, so they are easily reduced to ferric ions.

b Aluminum ions, divalent iron ions, chloride ions, sulfate ions.

b Ions can coexist in an acidic environment and will not react.

In acidic solutions, nitrate ions have strong oxidizing properties, and ferric ions can be oxidized to ferric ions, so they cannot coexist. In acidic solution, the oxidation of chlorine ions and sulfate ions is weak, and divalent iron ions cannot be oxidized into trivalent iron ions.

a Nitrate ions and hydrogen ions constitute nitric acid, which is oxidizing and cannot coexist with divalent iron ions in large quantities;

b Sulfuric acid composed of sulfate ions and hydrogen ions cannot oxidize divalent iron ions, let alone hydrochloric acid. so……

A Under acidic conditions, H+ cannot coexist, and NO3-+3FE2++4H+=3FE3++NO+2H2O can not coexist in redox reactions.

b Can coexist.

Ions that cannot be present under acidic conditions are:

1) Weakly acidic ions and weakly acidic acidic radical ions (such as clo-CO32-

s2-ch3coo-

hco3-hpo43-

oh-etc) reason: strong acid to weak acid.

2) Thiosulfate ions, silver ammonia ions [Ag(NH3)2+] (3) Some ions can exist alone under acidic conditions, but they cannot coexist under the influence of other ions, such as NO3- can coexist with H+, Fe2+ can coexist with H+, but NO3-, H+, Fe2+ can not coexist together, because nitrate has strong oxidation and can oxidize Fe2+

Ions that cannot be present under alkaline conditions are:

1) It can form a precipitate with OH- ions.

2）nh4+

H+ cannot coexist with OH- ions.

3) Acid root ions cannot coexist with oh- ions.

It cannot metathesis with hydrogen ions, including the formation of gas, the formation of precipitation, the formation of electrolytes such as weak acids and bases, and the inability to undergo redox reactions in acid solutions I don't understand, please ask Good luck.

One. Ions react with each other and cannot coexist in large quantities.

Ions that cannot coexist in large quantities in alkaline environment: Cu2+, Fe3+, H+, HCO3- Hpo42- NH4+, Al3+

Ions that cannot coexist in large quantities in an acidic environment: CO32-, S2-, HS-, HSO3-, and other volatile weak acids, OH-, CH3COO-, PO43-, HPO42-, H2PO, ALO2-, S2-, CO32-, C6H5O-

1.Combine with each other to form a precipitate. Such as: Ba2+ and SO42-, AG+ and Cl-, Cu2+ and OH-

2.Combine with each other to form volatile substances. Such as: H+ and S2-, HS-, CO32-, HCO32-, SO32-, HSO3-, etc.

3.Ions combine with each other to form weak electrolytes. Such as: H+ and OH-, PO43- weak acid group, etc.

4.The cation of the weak acid group and the weak base will undergo a double hydrolysis reaction. Such as: S2- and Al3+, Fe3+ and CO32-

5.Redox reactions occur between ions. Such as: Fe3+ and S2-, I-, Mno4- and Fe2+, S2-, I-, SO32-, etc.

6.The ions combine with each other to form complex ions. For example, Fe3+ and SCN- form [Fe(SCN)]2+ complex ions.

Two. Special conditions require that certain ions cannot coexist in large quantities.

1.In a colorless solution, colored ions cannot coexist in large quantities: for example, Cu2+, Fe2+, Fe3+, and Mno4- are all colored ions.

2.If the solution is strongly acidic, non-strong acid ions and OH- cannot coexist in large quantities. Such as:

In a solution with pH=1, OH-, S2-, HS-, CO32-, HCO3-, SO32-, HSO3-, CLO-, F-, PO43-, HPO42-, S2O32-, etc. cannot exist in large quantities.

3.In a strong alkaline solution, H+, acid roots (such as HCO3-, HSO3-, HS-) and non-strong alkaline cations cannot coexist in large quantities. For example, in a solution with pH=13, H+, Cu2+, HCO3-, etc. cannot coexist in large quantities.

4.In a solution with strong oxidizing particles, reducing ions cannot coexist in large quantities. For example, in a solution with a large number of Mno4- ions, I-, Fe2+, S2-, Br- and SO32- cannot coexist in large quantities.

5.Oxidizing ions cannot coexist in large quantities in solutions with strong reducing particles: for example, in solutions with a large number of I- ions, Fe3+, Mno4-, H++NO3- and Clo- cannot coexist in large quantities.

In an alkaline solution, ions that can react with OH- cannot coexist in large quantities.

Specifically, there are the following categories:

1. In a strong alkaline solution, there can be no large number of hydrogen ions (H+).

2. There can be no weak alkali metal ions in large quantities. Such as: magnesium ion (Mg2+), ferrous ion (Fe2+), iron ion (Fe3+), aluminum ion (Al3+), copper ion (Cu2+) and ammonium ion (NH4+), etc.;

3. There can be no large number of acid acid ions: HCO3, HSO3, HS, H2PO4, etc.