Why can t two ions coexist in large quantities when they are complexed

The problem of ion coexistence is whether ions can coexist in large quantities in solution, which involves comprehensive knowledge of the properties of ions and the acidity and alkalinity of the solution. Anything that can cause a significant change in the concentration of relevant ions in the solution due to the reaction cannot coexist in large quantities. For example, insoluble, difficult-to-ionize, gaseous substances may be converted into other kinds of ions (including oxidation-reduction reactions).

Generally, the following aspects can be considered: 1. Weak base cations only exist in more acidic solutions. For example, Fe3+, Al3+, Zn2+, Cu2+, NH4+, Ag+, etc. cannot coexist with OH- in large quantities. 2 Weak acid anions are only found in alkaline solutions.

For example, CH3COO-, F-, CO32-, SO32-, S2-, PO43-, and AlO2- cannot coexist with H+ in large quantities. 3. The acid anion of weak acid cannot coexist in large quantities in a solution with strong acidity or alkaline. When they encounter strong acids (H+), they will form weak acid molecules; When encountering a strong alkali (oh-), positive salt and water are generated.

Such as: HSO3-, HCO3-, HS-, H2PO4-, HPO42-, etc.4 If anions and cations can combine with each other to form insoluble or slightly soluble salts, they cannot coexist in large quantities. Such as:

Ba2+, Ca2+ and CO32-, SO32-, PO43-, SO42-, etc.; ag+ and cl-, br-, i-, etc.; Ca2+ and F-, C2O42-, etc.5 If the anion and cation undergo double hydrolysis reaction, they cannot coexist in large quantities. Such as: Al3+ and HCO3-, CO32-, HS-, S2-, AlO2-, CLO-, SiO32-, Fe3+ and HCO3-, CO32-, AlO2-, ClO-, SiO32-, C6H5O-, etc.; NH4+ and AlO2-, SiO32-, Clo-, CO32-, etc.6 cannot coexist in large quantities if anions and cations can undergo oxidation-reduction reactions.

Such as: Fe3+, I-, S2-; mNO4-(H+) and I-, Br-, Cl-, S2-, SO32-, Fe2+, etc.; no3-(H+) with the above anion; S2-, SO32-, H+7 cannot coexist in large quantities due to complexation reaction or other reactions, such as: Fe3+ and F-, Cn-, Scn-, etc.; H2PO4- and PO43- generate HPO42- and therefore do not coexist.

Hope!!!

The process by which a molecule or ion combines with a metal ion to form a new ion that is very stable is called a complexation reaction. Because the resulting complex is stable, the ions cannot be dissociated in solution, so the ions that undergo the complexation reaction cannot coexist in large quantities. The complexes are not necessarily precipitated, for example, white anhydrous copper sulfate forms a blue solution when dissolved in water, because the hydrated complex ions of copper are formed, which can be dissolved in water and are not precipitated.

You're right! If two ions are together, gas, water, and precipitation will be generated, strictly speaking, gas, difficult ionization substances, and insoluble substances will be generated, and in addition, redox reactions will occur, all of which cannot coexist in large quantities.

1. When some ions in the solution can react with each other to form insoluble substances, these ions cannot coexist in large quantities. Such as SO42- and Ba2+, PB2+, AG+; OH with Cu2+, Fe3+, Mg3+, Al3+, Zn2+; AG+ and Cl, Br, I, Co, So, S2; Mg2+, Ca2+, Ba2+, and CO32-, SO2-; S2 cannot coexist in large quantities with Cu2+, PB2+, etc.

2. When ions can combine to form difficult ionization substances, these ions cannot coexist in large quantities. For example, H+ and, OH, clo, CH3COO, HPO4 2-, H2PO4-OH and HCO3-, HS, HSO3-, H2PO4-, Hpo4 2-, H+, etc. cannot coexist in large quantities.

3. When ions can combine to form volatile substances, these ions cannot coexist in large quantities. Such as H and CO32-, SO3-, HCO3-, HSO3-, S2, HS; OH cannot coexist in large quantities with NH, etc.

4. When redox reactions can occur between ions, these ions cannot coexist in large quantities. Generally speaking, oxidizing ions (such as MNO, Clo, Fe3+, Hno3, etc.) and reducing ions (such as S2, I, Br, SO, Cl, Fe2+, etc.) cannot coexist in large quantities.

Pay attention to the following situations.

1) In the presence of H+, the oxidation of MNO, CLO and NO3- will be enhanced. For example, Fe2+, Na+, and NO3 can coexist; However, Fe2+, H+, and No3- cannot coexist, and Fe2+ is oxidized to Fe3+.

2) Fe2+ can coexist with Fe3+ because there is no intermediate valence state between them.

3) Fe3+ cannot oxidize Cl. NO3- (in the presence of H+) cannot oxidize Cl

4) It should also be noted whether the question gives the acidity and alkalinity of the solution, and whether the given solution is colorless. In addition to the ions, there should be a large amount of H+ in the acidic solution; In addition to the ions, there should be a large amount of OH in the alkaline solution. If the given solution is colorless, Cu2+ (blue), Fe2+ (light green), Fe3+ (yellow-brown), and MNO (purple) should be excluded.

5. Formation of complexes, such as: Fe3+ and SCN-

6. Double hydrolysis, weak acid group and weak base cation.

There can be no coexistence between HCO3-, HS and Al3+ Fe2+ Fe3+ NH4+.

Answer: Ions that definitely exist: CO32-, AlO2-, K+ ions that definitely do not exist:

SO42-, SO32-, NH4+, Al3+ analysis: (1) After adding nitric acid, the sulfite can be oxidized to sulfate, and the carbonic acid can also be reacted to form gas and the carbonate disappears. After that, barium nitrate was added, and there was no precipitation, and it was obvious that SO42- and SO32- were not present in the solution.

2) After adding hydrochloric acid, there is no obvious change at first, and then it changes to indicate that there are alkaline ions in the solution, and this is only ALO2-, which reacts with hydrochloric acid to form Al3+, and then hydrolysis reaction occurs to generate aluminum hydroxide precipitate and hydrogen ions, and the last gas is generated, indicating that there is CO32-, because (1) states that there is no SO32-, so it can be concluded. And if there is ALO2- in the solution, there can be no NH4+, so the root ion is excluded, and as for the elimination of K+, because it is a solution, it can't be only anion, right?

a. There is an interaction between ions, and there is also an interaction between molecules, so a is wrong;

b. Atoms can form molecules, and atoms and ions can be converted into each other, so the code is correct;

c. The particles that make up matter have molecules, atoms and ions, so C is correct;

d. The mass of an atom is mainly concentrated in the nucleus.

Therefore, d is correct to cover the mausoleum

Therefore, a

(1) Compounds with adjacent valence states of the same element do not react!

SO2 *****====> Strong reducibility!

H2SO4 (concentrated) ====> strong oxygen flowers.

But neither reacts!

2) Compounds with interphase valence states of the same element may react under certain conditions!

2h2s + so2 == 3s + 2h2o

Adjacent valence states of the same element can coexist, and if there is an intermediate valence state, a centering reaction will occur, that is, an interphase reaction!