Is the formation of precipitate endothermic or exothermic?

Not necessarily, if the general reaction can be carried out spontaneously and does not require heating and other conditions, the reaction is an exothermic reaction; If it needs to be heated, it is an endothermic reaction. A reaction in which the total energy of the reactant is greater than the total energy of the product is called an exothermic reaction. The reverse reaction must be an endothermic reaction.

For example, dilute sulfuric acid and barium hydroxide.

reaction, barium sulfate is generated.

precipitation and water, which is an acid-base neutralization reaction. Acid-base neutralization reactions are exothermic; For example, Ca(HCO3) 2 = heating = CaCO3 +CO2 +H2O In the reaction, Ca(HCO3) 2 is an aqueous solution, and there is a precipitate after the reaction, because the reaction is a decomposition reaction.

It is an endothermic reaction.

It mainly depends on what reacts to form a precipitate, such as the reaction of dilute sulfuric acid with barium hydroxide to generate barium sulfate precipitate and water, which is an acid-base neutralization reaction. Acid-base neutralization reactions are exothermic; For example, Ca(HCO3) 2 = heating = CaCO3 +CO2 +H2O In the reaction, Ca(HCO3) 2 is an aqueous solution, and there is a precipitate after the reaction, because the reaction is a decomposition reaction, it belongs to the endothermic reaction.

There are generally 7 types of exothermic reactions:

1) All combustion or ** reactions.

2) Acid-base neutralization reaction.

3) Most chemical reactions.

4) The reaction of active metals with water or acids to form H2.

5) Slow oxidation of substances.

6) Spontaneous redox reactions.

7) Thermite reaction.

Common types of endothermic reactions:

1) Most decomposition reactions:

CaCO3 = (high temperature) CaO+CO2

The relative magnitude of the total energy of the reactants and the products of the endothermic reaction.

CuSO4·5H2O=CuSO4+5H2O2).

3) Ionization. 4) A small number of chemical reactions.

c(s) + CO2 (g) = (high temperature) 2CO

I2+H2=2Hi (this reaction is reversible because the generated hydrogen iodide is unstable) 5) Others: 2NH4Cl(S)+Ba(OH)2·8H2O(S)=BACl2+2NH3 +10H2O

c + H2O (g) = (high temperature) CO + H2

This is indeterminate because of generation or discriminationprecipitationIt could be that the shirt was absorbing heat, or it could be thatExothermic reaction, so it's specific to see what kind of type it is.

If the reaction does not require any heating behavior, it can be carried out on its own, and this is often an exothermic reaction. If the process of generating the precipitate requires heating to complete, then this situation is an endothermic reaction.

In other words, the total energy of the reactant is larger than the total energy of the product, which is an exothermic reaction, and the excess heat needs to be released to complete the product.

If the energy of the reactant is less than the energy of the product, then it needs to absorb external heat to complete the reaction, which is an endothermic reaction.

Precipitation is the occurrence of a chemical reaction.

A substance that is insoluble in the solution where the reactant is located is formed. What is said here includes the precipitation of scientific terms, the precipitation of song titles and the original publication "Precipitation" of college students.

The precipitation-dissolution equilibrium is generally an endothermic reaction. Judgment method: look at the change of solubility with temperature.

If the temperature is higher, the solubility is greater, which is exothermic; If the temperature is lower and the solubility is smaller, it is endothermic. Because there is a precipitate dissolution equilibrium, if the temperature is higher, the solubility is larger, indicating that the equilibrium is moving in the direction of dissolution, so the precipitate dissolves and absorbs heat, so the precipitate is exothermic.

Sedimentation dissolution equilibrium refers to multiphase ion equilibrium, in which there is a dissolution and crystallization equilibrium between the insoluble electrolyte crystals and their dissolved ions in solution at a certain temperature. In a saturated solution, the dissolution rate of the electrolyte solid is equal to the precipitation rate of ion crystallization to form the solid, and the equilibrium state of the precipitation and dissolution reaction of the solid substance is reached, that is, the multiphase ion equilibrium.

The equilibrium of precipitation and dissolution is not achieved in both unsaturated and supersaturated solutions. In an unsaturated solution, the dissolution rate exceeds the precipitation rate, and the solids will all dissolve. In a supersaturated solution, the precipitation rate exceeds the dissolution rate, so that the precipitate continues to precipitate, and the ion concentration in the solution gradually decreases until the precipitation and dissolution reach equilibrium and become a saturated solution.

It mainly depends on what reacts to form precipitates, such as dilute sulfuric acid and barium hydroxide.

reaction, barium sulfate is generated.

precipitation and water, which is an acid-base neutralization reaction. Acid-base neutralization reactions are exothermic; Such as CA (HCO3).

2 = Heating = CaCO3 + CO2 + H2O

Ca(HCO3) in the reaction

2 is an aqueous solution, and there is a precipitate after the reaction, because the reaction is a decomposition reaction, it belongs to the endothermic reaction.

There are generally 7 types of exothermic reactions:

1) All combustion or ** reactions.

2) Acid-base neutralization reaction.

3) Most chemical reactions.

4) The reaction of active metals with water or acids to form H2.

5) Slow oxidation of substances.

6) Spontaneous redox reactions.

7) Thermite reaction.

Common types of endothermic reactions:

1) Most decomposition reactions:

CaCO3 = (high temperature) CaO+CO2

The relative magnitude of the total energy of the reactants and the products of the endothermic reaction.

CuSO4·5H2O=CuSO4+5H2O2).

3) Ionization. 4) A small number of chemical reactions.

c(s) + CO2 (g) = (high temperature) 2CO

I2+H2=2Hi (this reaction is reversible because the generated hydrogen iodide is unstable) 5) Others: 2NH4Cl(S)+Ba(OH)2·8H2O(S)=BACl2+2NH3 +10H2O

c + H2O (g) = (high temperature) CO + H2

Junior Chemistry - Endothermic and Exothermic phenomena during dissolution.

Hehe, it depends on the change of chemical bonds.

For example, dilute sulfuric acid reacts with barium hydroxide to produce barium sulfate precipitate and water, which is an acid-base neutralization reaction. Acid-base neutralization reactions are exothermic;

Yes. In an aqueous solution, the ionic reaction of combining two ions into a precipitate is an exothermic reaction. Because ionization is an entropy increase process, and the Gibbs free energy of the spontaneous reaction decreases, it can be calculated that the enthalpy of the reaction must be reduced, that is, the reaction is exothermic.

It mainly depends on what reaction, and the general exothermic reaction has the following points: (1) all combustion or ** reactions. 2) Acid-base neutralization reaction.

3) Most chemical reactions. 4) The reaction of active metals with water or acids to form H2. 5) Slow oxidation of substances.

6) Spontaneous redox reactions. 7) Thermite reaction. If the metathesis reaction is generated during the precipitate reaction, it is generally an exothermic reaction, except for the reaction between ammonium chloride and silver nitrate, which is an endothermic reaction.

The heat of the neutralization reaction to generate the precipitate is greater than the heat of neutralization, and the heat released is greater than that.

Because barium ions and sulfate form a precipitation process to form bonds, bond formation and exothermy.

Knowledge expansion: In a dilute solution, the heat of reaction when the acid and alkali are neutralized to form 1mol of liquid water is called the heat of neutralization

1.It must be a dilute solution of acid and base, because the concentrated acid solution and the concentrated alkali solution will be exothermic when they are diluted with each other, and the dilute solution reaction of strong acid and strong base can ensure that H + (AQ) + OH-(AQ) == H2O(L) neutralization heat is all.

kj·mol-1, while a weak acid or a weak base absorbs heat due to ionization in the neutralization reaction, and its heat of reaction is less than.

kj·mol-1；

3 to generate 1

mol water as a benchmark

Answer: It mainly depends on the reaction-like exothermic reaction: (1) combustion or ** reaction. (2) Acid-base reaction.

3) Digitalization and anti-masking. (4) Splash metal and water or acid H2 reaction. (5) Slow oxidation of substances.

6) Spontaneous oxidogenic reaction. (7) Thermite reaction, precipitation reaction, reduction reaction, and recombination reaction are generally exothermic reactions, except for ammonium chloride, and the reaction with silver nitrate belongs to endothermic reactions.