Are there any chemical reactions that neither absorb nor release heat?

Matter is atoms that are joined together. The essence of a chemical reaction is the recombination of atoms. For example, in O2+C=CO2, the oxygen atoms are originally connected to form oxygen molecules, the carbon atoms are connected to form elemental carbon, and one carbon atom and two oxygen atoms are connected to form carbon dioxide molecules after the reaction.

The atoms of matter are separated and then combined. And what holds the atoms together is an electrostatic force. Isn't there negatively charged electrons and positively charged nuclei in atoms?

The opposite charges of two atoms attract each other, and the same charges repel each other. This pull is known as the chemical bond. Pulling atoms apart (breaking bonds) consumes energy and is manifested as endothermy; The atoms come together (bonding) to release energy, which is manifested as exothermy.

Due to the difference in atoms, the strength of the chemical bonds (pulls) between the atoms in different substances is also different. If the pull (bond) between the reactant atoms is stronger than that of the product, then more energy is required to disassemble the reactant atoms, and the total reaction behaves as endothermy. Otherwise, it is exothermic.

If the bond strength of the product and reactant is the same, endothermic and exothermic cancel each other out, and the total reaction is neither endothermic nor exothermic. Unfortunately, the pulling force (bond strength) between atoms is generally different due to different atoms. Therefore, there is always a little more heat absorbed and heat released, so there is no chemical reaction that neither absorbs nor releases heat.

Personal understanding, please bear with me if the expression is inaccurate

Definitely not. Because since it is a chemical reaction, there must be changes in matter, and energy is stored in matter, which is stored with the synthesis of matter and released with the decomposition of matter.

If only the overall analysis were! See how you analyze it! For example, reversible reactions!

The chemical reaction is to break the old chemical bonds.

and the process of forming new chemical bonds.

Any chemical projection has a process of releasing energy and absorbing energy.

To break a chemical bond is to release energy, and to form a new chemical bond is to absorb energy.

Judge whether the chemical reaction releases energy or absorbs energy.

1. If the released energy is greater than the absorbed energy, it is the released energy.

2. If the absorbed energy is greater than the released energy, it is the absorbed energy.

In general, chemical reactions are mainly heat-based.

Reactions that release energy 1The combustion of any substance (such as hydrogen, carbon, sulfur, iron, aluminum) is mainly a chemical reaction) 2The reaction in which the basic oxide dissolves in water (which is also exothermic energy) absorbs energy 1Decomposition of salts (e.g., carbonate wax calcium resistance sodium bicarbonate.

etc. absorb heat and decompose).

Mainly decomposition reaction) 2Electrolysis of water or electrolysis of certain salts to obtain the elemental elements of active metals (water, electrolysis of hydrogen and oxygen, magnesium chloride.

Electrified into elemental magnesium and chlorine.

According to the ideal state, as long as the object absorbs heat, it will inevitably increase the internal energy and increase the temperature, but there is no ideal result in our real life, the object will diverge outward while absorbing heat, and if the work is done, the internal energy will be consumed, so the final feature is that the internal energy does not increase, and the temperature does not rise.

However, it should be noted that it does have such a process of internal energy increase, but because external factors do not show it, it still exists.

Hope it helps

For example, in the process of crystal dissolution, the temperature does not change, and the heat absorbed is used to increase the potential energy between molecules. The temperature of an object does not change, it only means that the average kinetic energy of its molecular thermal motion does not change, however, the potential energy between molecules may change, and the temperature does not change during the crystal dissolution process, and the heat absorbed is used to increase the potential energy between molecules.

There are two ways to change the internal energy of an object: work done and heat transfer. While absorbing heat and doing external work, the internal energy does not necessarily increase.

The crystals melt, absorb heat, and the internal energy increases, but the temperature does not change.

The internal energy of the object absorbing heat does not necessarily increase", because it is also necessary to consider whether the object does work externallyFor example, if I exercise next to the heater, I absorb the heat but do the work, and the internal energy does not necessarily increase.

Ensuring authority.

If the object absorbs heat and also does external work, and the external work is greater than the absorbed heat, the internal energy of the object not only does not increase, but decreases. When the water boils, the temperature does not increase, and the internal energy increases!

Internal energy includes kinetic energy and potential energy, although the internal energy increases, it is possible that the potential energy increases, the kinetic energy does not change, the kinetic energy is related to the temperature, the kinetic energy does not change, and the temperature does not change.

The object absorbs the heat and may also work on the outside! When the external work is greater than the heat absorbed, its internal energy does not increase, and the temperature does not rise.

For example, if one kilogram of 0 degrees Celsius ice absorbs heat and melts into 0 degrees Celsius water, the internal energy increases, and the temperature remains the same.

For example, the endothermic temperature does not change when the crystal melts.

When it absorbs heat, there are situations where it consumes its internal energy.

Temperature is used to represent an object.

The internal energy is the total energy contained in the object, that is, the sum of all molecular kinetic energy and molecular potential energy, and the internal energy of the object is related to the temperature and volume. Heat refers to the amount of change in internal energy during heat transfer. Hence unlike internal energy, which is a state quantity, heat is a process quantity.

An object has internal energy, but it cannot be said to have heat or contain heat. The amount of energy that changes in an object during heat transfer can only be expressed in terms of heat.

The change in the temperature of an object can change the internal energy of an object, and the amount of heat transferred can measure the amount of energy changed in the object. When an object absorbs or emits heat, its internal energy will change, but its temperature will not necessarily change. , the internal energy increases, but the temperature remains unchanged at 0; Similarly, when an object emits heat, the temperature does not necessarily decrease.

It can be summarized as the temperature of an object changes, its internal energy must change, but when the internal energy changes, its temperature does not necessarily change.

The internal energy of the object can be explained as the molecular potential energy and the molecular kinetic energy, the temperature is the macroscopic manifestation of the kinetic energy of the molecule of the object, when the temperature does not change, that is, the molecular kinetic energy does not change, and the increase of internal energy is the increase of molecular potential energy, for example, the temperature does not change in the process of crystal from solid to liquid state, the distance between molecules becomes larger, and the molecular potential energy increases, then the internal energy increases.

Internal energy does not specifically refer to temperature, for example, a gas expands without the same temperature after absorbing heat, which is what you are talking about. Seek adoption.

A chemical reaction is the process of breaking an old chemical bond and forming a new one, and any chemical projection has a process of releasing energy and absorbing energy.

To break a chemical bond is to release energy.

To form a new chemical bond is to absorb energy.

Determine whether a chemical reaction releases energy or absorbs energy analysis.

1. The energy released is greater than the energy absorbed.

then it is the release of energy.

2. The absorbed energy is greater than the released energy.

is the absorption of energy.

General. Chemical reactions are all heat-based transfers.

A reaction that releases energy.

1.Combustion of any substance (e.g. hydrogen.

carbon-sulfur-iron-aluminum) is mainly a chemical reaction).

2.Basic oxides are soluble in water.

It is also exothermic energy).

A reaction that absorbs energy.

1.Decomposition of salt.

Such as: calcium carbonate.

sodium bicarbonate, etc.

Absorb heat and decompose)

Mainly decomposition reactions).

2.Electrolysis of water or electrolysis of certain salts to obtain elemental elements of active metals (water electrically decomposes hydrogen and oxygen, magnesium chloride electrically decomposes into elemental magnesium and chlorine).

It must be wrong, energy conversion is indeed conserved, but if you strike a match, why do you want to draw it, because the initial energy at the beginning is not enough, and the friction generates heat, that is to say, the reaction begins to absorb heat, and after it happens? When the match is lit, the reaction begins to release heat, and the heat released is much greater than the heat absorbed, and the overall reaction is exothermic. The heat absorbed by this reaction is part of the heat that starts to rub, and the heat released is the chemical energy contained in the chemicals on the match head.

The heat released is greater than the absorption, which is manifested as heat release.

Because most chemical reactions have a thermal effect, either exothermic or endothermic, if the heat released > the heat absorbed, it is an exothermic reaction.

If the heat emitted < the heat absorbed, it is an endothermic reaction.

If the heat emitted = the heat absorbed, neither exothermic nor endothermic .

Not "certainly", but "maybe".

In a chemical reaction, exothermic and endothermic exist at the same time. (Wrong explanation upstairs).

Because some of it is provided by internal energy, it is like igniting hydrogen, which will not absorb heat, but will only release heat, relying on the energy difference between the reactant and the product.

The chemical reaction is either endothermic or exothermic, and it is impossible to do both endothermic and exothermic at the same time, so it is wrong.

Chemical reactions are always accompanied by changes in energy, and there are thousands of chemical reactions, some are endothermic and some are exothermic. There are thousands of them, and it's hard to give examples. However, most of these reactions have regularities, decomposition reactions are generally endothermic, and chemical reactions are generally exothermic, of course, in chemistry can not be full of words, because there are many, many special cases in chemistry.

So you just have to remember the exceptions, not the exceptions, then the general is the rule.

Neutralization reaction: H+ OH- = H2O

Analysis: In order to break the H-O bond in the reverse reaction, energy needs to be supplied, so the reverse reaction is endothermic.

The neutralization reaction is the formation of chemical bonds by H+ and OH-, both of which are very high energy, and the energy of the system decreases, so the energy must be released, and the energy released is expressed in the form of heat--- that is, it is exothermic and heat is released.

Hydrogen ions and hydroxide ions that neutralize the same amount of matter will release heat, and the heat emitted is a fixed value, about 30 kJ mol

From unstable to steady.

Belch. If you don't believe this, can you do experiments? It is exothermic because of the breaking of the chemical bond.