What are the conditions for metathesis reaction What are the conditions for neutralization reaction

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The essence of the metathesis reaction is that the two substances that undergo the metathesis reaction exchange ions with each other in the aqueous solution, and combine into substances that are difficult to ionize--- precipitation, gas, and water, so that the ion concentration in the solution decreases, and the chemical reaction is carried out in the direction of the reduction of ion concentration.

Summary] Conditions under which the metathesis reaction occurs:

1) Reactants: must be soluble (including soluble acids).

2) Product: precipitation, gas or water generation.

The conditions under which the metathesis reaction occurs.

Basic oxide + acid – salt + water.

For example: cao+2hcl=cacl2+h2o]base + acid--- salt + water.

For example: NaOH+HCl=NaCl+H2O] type of metathesis reaction Salt (dissolved in water or dissolved in acid) + acid --new salt + new acid.

For example: BaCl2 + H2SO4 = BaSO4 + 2HCl] salt (soluble) + base (soluble) - new salt + new base.

For example: Na2SO4 + BA(OH)2=BaSO4 +2NaOH] salt (soluble) + salt (soluble) - two new salts.

For example: Na2SO4 + BACL2 = 2NaCl + BaSO4 ] The conditions under which the metathesis reaction occurs: (the following conditions are met at the same time) 1) Reactants: must be soluble (including soluble acids).

2) Product: precipitation, gas or water generation.

ab+cd=ad+cb (because the element of positive valence should be in front, it should be cb).

To put it simply, as long as the production of precipitation, gas, and weak electrolytes is satisfied. The metathesis reaction can occur. Weak electrolytes include weak acids and weak alkaline water.

For example, HCl + NaCl = NaCl + HCl, although there is no precipitation, gas, water, but there is a weak acid hypochlorous acid formation, it can also occur. According to the conditions under which the metathesis reaction tends to be completed, certain conditions are required for the metathesis reaction to occur.

The following analyzes the conditions for the occurrence of metathesis reaction according to the following four types of reactions from the aspects of reactants and products. The conditions for the metathesis reaction of acids, alkalis and salts in the solution are precipitation, gas release, or water formation. (1) Acid + salt – new acid + new salt The acid in the reactant must be soluble', at least one of the substances in the product is gas or precipitate or water.

For example: 2HCl CaCO3=CaCl2 H2O CO2

2) Acid + base – salt + water reactants at least one of them is soluble. For example: H2SO4 Cu(OH)2=CuSO4 2H20

3) Salt + Salt – Two new salts in the reactant are both soluble, and at least one of the two salts resulting from the reaction is insoluble. For example: Na2SO4 BACl2=2NaCl BaSO4

4) Salt + alkali - new salt + new alkali reactants should generally be soluble, and at least one of the products is a precipitate or gas (only ammonia salt reacts with alkali to form gas). For example: 2NaOH CuSO4=Na2SO4 Cu(OH)2 ; NaOH NH4Cl=NaCl NH3 H2O Fe(OH)3 does not react with NaCl Note:

Whether acid + alkaline oxide – salt + water and alkali + acid oxide – salt + water are metathesis reactions is inconclusive, and it is recommended to avoid the above two reactions when answering the question. Conditions under which the metathesis reaction occurs: (the following conditions are met at the same time).

1) Reactants: must be soluble (including soluble acids).

2) Product: There must be precipitate or gas or water or weak electrolyte.

Metathesis reaction can be divided into the following five types, in essence, in addition to the requirements for the products, the occurrence of the metathesis reaction also has certain requirements for the reactants, that is, when there is no acid in the reactants, the reactants should be soluble in water, which is summarized and compared as follows:

Acid + metal oxide salt + water.

Acid + alkali salt + water.

Acid + Salt New acid + new salt.

Alkali + salt New alkali + new salt (reactants should be soluble in water).

Salt + salt New salt + new salt (reactants should be soluble in water).

The three conditions under which metathesis reactions can occur (i.e., precipitation or gas or water in the product) have effectively guided scientific experiments and production practices for a long time. It has been shown through practice that a substance or resalt can be precipitated in the reaction due to temperature difference or concentration, and metathesis reaction can also occur.

The 2005 Nobel Prize in Chemistry was awarded to three scientists for their achievements in the study of olefin metathesis reactions. The three scientists were Yves of the French Petroleum Institute. Chauvin, Robert of the Massachusetts Institute of Technology.

Grubb and Richard of Caltech, California. Schrock. They discovered Chauvin's mechanism of "exchange dance partners" for olefin metathesis reactions, namely:

The metathesis reaction of olefins is a process in which the carbon-carbon double bonds in olefins are dismantled, exchanged, and recombined under the catalytic action of metal carbene compounds to form new molecules.

1) Basic oxide acid salt H2O

fe2o3+6hcl==2fecl3+3h2o；fe2o3+3h2so4==fe2(so4)3+3h2o

cuo+h2so4==cuso4+h2o；zno+2hno3==zn(no3)3+h2o

2) Alkaline acid salt H2O

cu(oh)2+2hcl==cucl2+2h2o；cu(oh)2+h2so4==cuso4+2h2o

naoh+hcl==nacl+h2o；2naoh+h2so4==na2so4+2h2o

naoh+hno3==nano3+h2o；mg(oh)2+2hno3==mg(no3)2+2h2o

ba(oh)2+h2so4==baso4↓+2h2o

3) Acid salt, new salt, new acid.

caco3+2hcl==cacl2+h2o+co2↑；na2co3+2hcl==2nacl+h2o+co2↑

hcl+agno3==agcl↓+hno3；h2so4+bacl2==baso4↓+2hcl

ba(no3)2+h2so4==baso4↓+2hno3

nahco3+hcl==nacl+h2o+co2↑

Occurrence conditions

Basic conditions: The two substances in which the metathesis reaction takes place can exchange ions in an aqueous solution and combine to form a substance that is difficult to ionize (precipitate, gas or weak electrolyte).

1. Basic oxide + acid: the acidity of the acid is strong (such as HCl, H2SO4, HNO3, etc.), and the reaction can occur.

2. Acid + alkali (neutralization reaction): when the acid and alkali are weak, no reaction occurs.

3. Acid + salt: strong acid to weak acid; There is precipitation after the exchange of ions; strong acids react with carbonates; A reaction can occur when one condition is met.

4. Alkali + salt: strong alkali reacts with ammonium salt; Both reactants are soluble, and there are one of three after the exchange of ions: precipitation, water, and gas; A reaction can occur when one condition is met.

5. Salt + salt: both reactants are soluble, and there is one of the three of precipitation, water and gas after the exchange of ions, and the reaction can occur if one condition is met.

1.Formation of insoluble substances: such as the formation of BaSO4, AGCL, CaCO3 and other precipitates.

2.Formation of gases or volatile substances: such as the generation of CO2, H2S and other gases3Generate substances that are difficult to ionize: such as the generation of H2O, weak acids, weak bases, etc. There is weak electrolyte production.