What is the difference between double hydrolysis and complete double hydrolysis

First, the ions contained are different.

General double hydrolysis: general double hydrolysis contains NH4+, except for ammonium silicate. For example: ammonium carbonate, ammonium bicarbonate, ammonium sulfide, ammonium acetate, sodium silicate, ammonium sulfite, etc.

Complete dihydrolysis: Complete dihydrolysis generally contains metal ions. For example: aluminium carbonate, aluminium bicarbonate, iron carbonate, aluminium sulfide, etc. Except for Fe3+ and sulfur-containing weak acid ions, redox reactions need to be considered.

Second, the products are different.

General double hydrolysis: The products of general double hydrolysis have no precipitation and gas.

Complete double hydrolysis: The products of complete double hydrolysis are precipitated and gas.

3. Chemical equations are written differently.

General double hydrolysis: For the chemical equation of general double hydrolysis, the reversible sign should be written, and the gas symbol should not be written.

Complete double hydrolysis: The chemical equation of complete double hydrolysis should be written with equal signs, precipitation and gas symbols.

When you say double hydrolysis, you should mean both hydrolysis.

For example. CH3CoonH4 is a substance that is hydrolyzed by two ions, and the hydrolysis produces H+ and OH-, and the two hydrolysis promote each other, but although they promote each other, this substance exists in the aqueous solution, so the degree of promotion is not enough to reach a thorough degree, so it is called hydrolysis.

Thorough double hydrolysis is what we generally call double hydrolysis, such as Al3+ and CO32-, HCO3-, etc., which are so promoted that they can be completely carried out.

It refers to the OH- generated by the hydrolysis of weak acid roots, and H+ generated by the hydrolysis of weak alkali cations, because H+ and OH- will not coexist in large quantities, so the H+ generated by the hydrolysis of weak alkali cations promotes the hydrolysis of weak acid groups, and the OH- generated by the hydrolysis of weak acid radicals promotes the hydrolysis of weak alkali cations, and the ionization degree of water continues to increase.

The double hydrolysis reaction refers to the mutual hydrolysis of weak acid anions and weak base cations, such as trivalent aluminum ions and bicarbonate, until the reaction is complete. However, in fact, aluminum ions and bicarbonate do not necessarily undergo complete dihydrolysis, as long as the reaction conditions are slightly controlled, aluminum ions and bicarbonate can react to form basic alumina carbonate.

One of the conditions for the double hydrolysis reaction to occur is that the hydrolysate is a very small solubility substance that is easily separated from the reaction system. Of course, if the degree of hydrolysis is very large, the hydrolysis reaction can also be considered complete.

For example, the main chemicals in foam fire extinguishers are sodium bicarbonate and aluminum sulfate, which promote the hydrolysis of each other to generate carbon dioxide gas and aluminum hydroxide precipitation, resulting in a large amount of foam.

al(hco3)3=al(oh)3↓+3co2↑

al2s3+6h2o=2al(oh)3↓+3h2s↑

aln+3h2o=al(oh)3↓+nh3↑

Weak acid anions and weak base cations promote the hydrolysis of each other in the aqueous solution, and the degree of hydrolysis increases. The hydrolysis problem consists of complete hydrolysis and incomplete hydrolysis. Some mutual hydrolysis reactions cannot be carried out completely, while some mutual hydrolysis reactions can be carried out completely (commonly known as "double hydrolysis reaction").

Double hydrolysis refers to the hydrolysis of weak acid groups to form OH-, weak base cation hydrolysis to generate H+, because H+ and OH- do not coexist in large quantities, so the weak base cation hydrolysis generated H+ promotes the hydrolysis of weak acid groups, and at the same time, the OH- generated by the hydrolysis of weak acid groups promotes the hydrolysis of weak alkali cations, and the degree of water ionization continues to increase.

For example, NH4+ +CH3COO- +H2O<=>CH3COOH +NH3·H2O

The degree of hydrolysis of the above formula is not very large, because the acidity of CH3COOH and the alkalinity of NH3·H2O are not very weak.

If the hydrolysate is very acidic and alkaline, the hydrolysis is very thorough.

For example: Al3+ +3HCO3-=Al(OH)3 +3CO2

Because it is thorough and violent, the product Al(OH)3 has flame retardant effect and CO2 has fire extinguishing effect, so Al2(SO4)3 and NaHCO3 can be used as raw materials for foam fire extinguishers.

Middle school to remember.

Al3+ is double hydrolyzed with Al(OH)4- (or AlO2-) HCO3-, CO32-, SO32-, HSO3-, S2-, HS-, etc.

Fe3+ is dihydrolyzed with Al(OH)4- (or AlO2-), HCO3-, CO32-, etc.

Al(OH)4- (or AlO2-) is dihydrolyzed with Al3+, Fe3+, NH4+, etc.

Complete double hydrolysis is complete hydrolysis, write equal signs, and some of the products can generate precipitates or gases.

Generally, the double hydrolysis is not complete, the reversible sign is written, and there is no precipitation or gas in the product.

For example: NH4F (general double hydrolysis) Al3+ and CO32- (complete double hydrolysis) NH4+ +F- +H2O + HF2 Al3+ +3CO32- +3H2O = 2Al(OH)3 (precipitation) + 3CO2( ).

Thorough hydrolysis tends to be unidirectional.

On the other hand, double hydrolysis is to promote mutual hydrolysis, such as alo2-&al3+

Hydrolysis is the property of salts, such as the hydrolysis of iron salts (weak alkali salts or weak acid salts, which are only hydrolyzed when there is weakness) and double hydrolysis is a reaction between weak acid groups and weak bases (which can be partial double hydrolysis and complete double hydrolysis), such as CH3COO- and NH4

Partial double hydrolysis, HCO3, occurs

and Al3+, complete dihydrolysis will occur.

Hydrolysis refers to the reaction of ions with water to form precipitates or bubbles, and is generally incomplete and reversible, such as the hydrolysis of iron ions into iron hydroxide in water.

The double hydrolysis generally refers to the reaction of two ions that can be hydrolyzed with water at the same time, promoting each other, so that the final reaction is complete, such as aluminum ions and metaaluminate ions, when there are aluminum ions and hydrogen ions at the same time, aluminum ions will react with water to form aluminum hydroxide and hydrogen ions, metachloroate ions will react with water to form aluminum hydroxide and hydroxide ions, and the products of the two reactions (hydrogen ions and hydroxide ions) will react to form water, so the balance is pushed to move in the direction of positive reaction, promote each other, and finally only aluminum hydroxide remains.

Double hydrolysis promotes each other, there is also mutual inhibition, mutual promotion can complete hydrolysis, hydrolysis is generally weaker and more hydrolysis, dominant who is strong and who is sexual, except for NAAC,

Hydrolysis refers to the hydrolysis reaction of reactants, which is a reversible reaction and relatively weak.

Double hydrolysis is when both reactants are hydrolyzed, and each gets its own functional group from the other, and the reaction is strong.

What is the difference between chemically complete double hydrolysis and incomplete double hydrolysis.

For example, Fe3+ and CO32- are completely double hydrolyzed, after the reaction, Fe3+ all becomes Fe(OH)3, and CO32- all becomes CO2, and the equation uses an equal sign, that is to say, Fe3+ and CO32- cannot coexist in large quantities;

For example, NH4+ and CO32- are partially double hydrolyzed, only a small part of NH4+ generates NH3·H2O, and a small part of CO32- all become H2CO3, and the equation uses a reversible sign, that is, NH4+ and CO32- can coexist in large quantities.

Double hydrolysis refers to the reaction in which both the anions and cations that make up the salt undergo hydrolysis reaction (i.e., the hydrolysis of weak acid and weak alkali salt).

For example, solid aluminum carbonate meets water to produce aluminum hydroxide and carbonic acid (decomposition to produce carbon dioxide and water), aluminum chloride reacts with sodium bicarbonate to form carbonic acid (decomposition produces carbon dioxide and water), sodium chloride and aluminum hydroxide, iron chloride and sodium bicarbonate also react in the same way to produce carbonic acid (decomposition produces carbon dioxide and water), sodium chloride and iron hydroxide, and so on.