What are endothermic reactions and exothermic reactions in chemistry

Endothermic reactions: the manufacture of water gas, the mixing of ammonium chloride solids with barium hydroxide solids, the hydrolysis of salts, the reaction of CO2 and C, electrolysis reactions, HI pyrolysis, carbon-oxygen double bonds and hydrogen addition, etc.

Exothermic reaction: combustion reaction, acid-base neutralization, displacement reaction, industrial ammonia production, alcohol is oxidized to aldehyde, aldehyde is oxidized to acid, alkene or alkyne is added to halogen elements, etc.

Endothermic: ammonium chloride solid mixed with barium hydroxide solid, HI pyrolysis, carbon-oxygen double bond and hydrogen addition, manufacture of water gas, etc.

High electrolysis, hydrolysis, galvanic cells will be endothermic. Exothermic: industrial ammonia production, combustion reactions, remember chemical reactions, neutralization reactions, most redox reactions, and many organic ones are also exothermic.

Exothermic reactions include combustion, active metals react with acids to form hydrogen, quicklime and water reactions, and neutralization reactions.

There is an endothermic reaction.

Carbon and carbon dioxide react, hydrogen reduces metal oxides, barium hydroxide crystals and ammonium chloride solids are mixed.

The endothermic reaction is mainly a decomposition reaction, such as high-temperature calcined limestone: the exothermic reaction is mainly a neutralization reaction, most of the redox reactions, and chemical reactions.

Endothermy: Ice water

Exothermic: Combustion is an exothermic reaction, as well as lime + water.

I haven't looked at chemistry for a long time, and I forgot all the symbols-

Most of the chemical reactions are exothermic reactions, and a few are endothermic reactions (eg: C + CO2 = high temperature = 2CO).

Most of the decomposition reactions are endothermic reactions, and a few are exothermic reactions (eg:2hi==H2+I2).

The acid-base neutralization reaction is an exothermic reaction, while hydrolysis is an endothermic reaction. Wait a minute.

Exothermic reactions are:

1.All combustion reactions such as hydrogen, charcoal combustion, etc.

2.Acid-base neutralization reaction.

3.Most chemical reactions.

4.Thermite reaction.

5.Metals react with acids, etc.

There is an endothermic reaction.

1.Most of the decomposition reactions.

Reaction to NH4Cl crystals. Wait.

An endothermic reaction is a chemical reaction that absorbs heat in the process.

In a chemical reaction, a reaction in which the total energy of the reactants is greater than the total energy of the products is called an exothermic reaction.

Endothermic reactions: most of the decomposition reactions, C, Co, H2 reduction of gold Bai oxide, barium hydroxide with eight crystal water and ammonium chloride reaction, most of the salt hydrolysis reactions, a few chemical reactions (generally not required to master).

Exothermic reactions: most of the chemical reactions, acid-base neutralization reactions, metal and acid reactions, metal and water reactions, combustion reactions, ** reactions.

Exothermic reactions: combustion of combustibles; Acid-base neutralization reaction. Most chemical reactions. Metal and acid displacement reaction; slow oxidation of substances, etc. Endothermic reaction:

Most of the decomposition reactions. hydrolysis of salts and ionization of weak electrolytes; Ba(OH) reacts with NH4Cl; Reaction of carbon and water vapor, C and CO2, etc.

Heat of reaction of the neutralization reaction:

The heat emitted by the acid-base neutralization reaction.

Heat of neutralization: In dilute solution, the amount of heat neutralization heat released when acid and base are neutralized to form 1 mol of water is independent of the amount of reactants.

Enthalpy: The energy possessed by the substance itself is expressed in enthalpy.

Symbol: H enthalpy change H = h product - h reactant.

When h<0, it is an exothermic reaction.

When h>0, it is an endothermic reaction.

Factors influencing enthalpy and the magnitude of enthalpy.

1. Different substances, H is different, H is also different.

2. The same substance, the larger the amount of the substance, the greater the h, the greater the h 3. For the same substance, h (gas) > h (liquid) > h (solid) enthalpy change is different from the heat of reaction

The size of h depends on the symbol, and the size of q does not depend on the symbol.

Comparison of exothermic and endothermic reactions.

Endothermic reactions (1) Several common reactions, such as: 2NH4Cl(S)+Ba(OH)2·8H2O(S)=BaCl2+2NH3 +10H2O C+H2O(G)=CO+H2 C(S)+CO2(G)=2CO

Most of the decomposition reactions, such as: CaCO3 = (high temperature) Cao + CO2 CuSO4·5H2O = CuSO4 + 5H2O Dissolution of some substances, such as ammonium nitrate dissolution, etc. (It can also be said to be the hydrolysis of salts, which must be an endothermic reaction at this time.)

For example, ammonium root hydrolysis is endothermy).

2) Special endothermic reactions, such as: C+CO2=2COi2+H2=2HI (this reaction is reversible, because the generated hydrogen iodide is unstable).

3) Ionization reaction.

4) Hydrolysis of salts.

5) Barium hydroxide crystals are mixed with ammonium chloride crystals.

6) C, H2 CO as a reducing agent.

There should be 1 decomposition reaction in junior high school, such as: CaCO3 = (high temperature) CaO+CO2

2 C, H2 Co as a reducing agent reaction.

Common exothermic and endothermic reactions in junior high school chemical reactions:

Common exothermic reactions: all combustion reactions; Neutralization reaction ; Most chemical reactions. Reactive metals react with water or acid; slow oxidation of substances ;

Common endothermic reactions: most decomposition reactions; c+co2＝2co；h2+cuo＝cu+h2o；c+ h2o＝co+h2；ba(oh)2 · 8h2o+2nh4cl=bacl2+2nh3↑+10h2o。

Common exothermic bench noisy and endothermic reactions in junior high school chemical reactions:

Common exothermic reactions: all combustion reactions; Jujube Hu serves neutralization reaction; Most chemical reactions. Reactive metals react with water or acid; slow oxidation of substances ;

Common endothermic reactions: most decomposition reactions; c+co2＝2co；h2+cuo＝cu+h2o；c+ h2o＝co+h2；ba(oh)2 · 8h2o+2nh4cl=bacl2+2nh3↑+10h2o。

The so-called exothermic is to release heat.

The essence of a chemical reaction is the breaking of old bonds and the formation of new ones. Breaking a bond requires absorbing energy, while forming a new bond releases energy. If more heat is released than is absorbed, the reaction is exothermic.

If more energy is absorbed than is released, the reaction is endothermic.

To put it simply, if the total energy of the reactant is greater than the total energy of the product, it will be exothermic; Otherwise, it absorbs heat.