Why does combustion produce heat ?

The essence of combustion that we usually call refers to the reaction of organic matter with oxygen, and the main component of organic matter is hydrocarbons, which can be expressed by the general formula CN(H2O)2N+2, (also known as carbohydrates);Reactive:

cn（h2o）2n+2o2co2

The essence of the H2O reaction is:

The breaking of the C-H bond, the formation of the C-O and H-O bonds, the bond energy of the C-H bond is greater than the bond energy of the C-O bond, and the excess bond energy is released in the form of heat energy (I can't remember the specific data). Combustion heat is generated.

The sun's glow and heat generation is a nuclear reaction, and unlike normal combustion, atomic energy is converted into light energy and heat energy.

Combustion is the conversion of chemical energy into internal energy.

Because of the strong interaction between particles, breaking bonds into bonds can be understood as the conversion between kinetic energy and potential energy between examples, and the converted "kinetic energy" becomes molecular kinetic energy and becomes internal energy.

It is not necessary to release more heat than it receives.

C+H2O=Co+H2 is the opposite.

The sun is converted from nuclear energy to internal energy, with a mass loss, e=mc2

Intense oxidation reaction due to the intense electron state transition (radical excitation) emits photons Molecules move violently The sensation of heat is actually the sensation of intense motion of molecules.

The definition of combustion is a redox reaction that is intense, glowing and heating, and why do you say it produces heat?

The formation of chemical bonds releases energy, interrupts the absorption of energy, and different chemical bonds have different energies, and when more energy is released than is absorbed, the chemical reaction is exothermic.

Plants carry out photosynthesis to convert light energy into chemical energy and store it in the synthetic organic matter, and when it is re-burned, the chemical energy is converted into heat energy and released.

Internal energy is converted into thermal energy i.e. chemical energy.

Chemical energy is converted into heat energy.

Heat of combustionIt refers to the heat released when a substance undergoes a complete combustion reaction with oxygen.

It is generally measured in the amount of a unit substance.

Measurement of the energy emitted per unit mass or unit volume of combustion, such as the combustion of a booklet. The combustion reaction is usually hydrocarbons.

Carbon dioxide is burned in oxygen.

water and exothermic reactions. The heat of combustion can be measured with a bullet calorimeter, or it can be obtained by subtracting the enthalpy of the reactants and products directly from the table.

Calculation of heat of combustion:

The heat of combustion is measured using 1 mol of combustible material as the standard, so when calculating the heat of combustion, the thermochemical equation is used.

The stoichiometric number of other substances often appears as fractions: e.g. H2(G) + 1 2O2(G) = H2O(L);δh= kj·mol 1 The fraction represents the number of moles (i.e., the amount of substances participating in the reaction) rather than the number of molecules, so it is reasonable.

Note: Chemical equation coefficients are integers only, while thermochemical equations can have fractions.

In the thermochemical equation, δh denotes the difference between the total enthalpy of the product and the total enthalpy of the reactant. Heat of reaction.

If the macro δh of the medium slag chain is negative, it is an exothermic reaction.

is positive, then it is an endothermic reaction.

The heat of combustion is a type of heat of reaction, and its δh is negative.

The above content reference: Encyclopedia - Heat of Combustion.

Refers to heat. Heat is the amount of energy transferred during heat transfer. It reflects the amount of internal energy transferred in the process of heat transfer, which is a measure of how much internal energy is transferred, and is a process quantity, which should be expressed by "absorption" or "release" rather than "have" or "contain".

The unit of heat is "joules".

Internal energy is a form of energy, which is the sum of the kinetic energy and potential energy of all the molecules in the object moving randomly. Internal energy, like temperature, is also a state quantity and is usually modified with words such as "have".

The magnitude of internal energy is related to the mass, volume, temperature, and type of matter that makes up the object. At this stage, the main focus is on the relationship with temperature. When the temperature of an object increases, its internal energy increases, and when the temperature decreases, its internal energy decreases.

The heat of combustion (δCH0) refers to bai

The amount of heat emitted when a substance reacts with oxygen during combustion. It is generally used.

The amount of DAO per unit of substance, the amount of energy emitted when the fuel per unit of mass or single weight volume is combusted. The combustion reaction is usually a reaction in which hydrocarbons are burned in oxygen to produce carbon dioxide, water, and exothermic. The heat of combustion can be measured with a bullet calorimeter, or it can be obtained by subtracting the enthalpy of formation (δfh0) of reactants and products directly by looking up the table.

Heat of combustion: The amount of heat emitted when a substance undergoes a complete combustion reaction with oxygen.

Heat. Heat refers to the change of the state of the system and the destruction of the thermal equilibrium conditions, that is, when there is a temperature difference between the system and the outside world, we call the thermal interaction between the system and the outside world.

As a result of the action, energy is transferred from a hot object to a low temperature object, and the energy transferred at this time is called heat. Heat and work are two different forms of energy transfer that accompany the change of the state of the system, and they are measures of the transfer of energy in different forms, and they are both related to the intermediate process of the state change, so they are not a function of the state of the system.

Internal energy is, from a microscopic point of view, a statistical average of the sum of the energies of the random motion of molecules. In the absence of an external field, the energy of the random motion of the molecule includes the kinetic energy of the molecule, the potential energy of the interaction between the molecules, and the energy of the internal motion of the molecule. The internal energy of an object does not include the kinetic energy of this object when it is in motion as a whole and its potential energy in the gravitational field.

In principle, the internal energy of an object should include the sum of the kinetic energy, potential energy, chemical energy, ionization energy and nuclear energy inside the nucleus of all microscopic particles, but in the process of changing the general thermodynamic state, the molecular structure, atomic structure and nuclear structure of the substance do not change, so the change of these energies can not be considered.

First of all, let's clarify the meaning of internal energy and heat.

In the high school physics textbook, the chapter on the internal energy of objects and the laws of thermodynamics points out that internal energy is a state quantity, and heat is a process quantity.

To put it bluntly, internal energy is a physical quantity that indicates the state of an object, while heat is an intermediate quantity in energy exchange when internal energy changes.

So generally speaking, there is a change in internal energy, emphasizing that it has changed. Rather than absorbing heat, it emphasizes that it only exists in a process of change.

Then, the problem of lz is very well explained, the matter in different states of the chemical reaction has different internal energy, and the chemical change is often accompanied by the thermal effect, which refers to the fact that the internal energy of the reactant and the product is different, so by the law of conservation of energy, the difference of this part of the internal energy becomes the heat released or absorbed and escapes into the surrounding space, becoming the internal energy of the surrounding objects and air, which is manifested as the increase or decrease of temperature on a macroscopic scale.

Therefore, the heat of combustion in fuel combustion refers to the heat released (fuel combustion must be exothermic in order to supply energy), that is, the difference between the internal energy of the reactant and the internal energy of the product.

e(reactant)-e(product)=q

In the unit of coul j, it is energy, internal energy is a general term for energy, and heat is a noun for non-energy.

Heat, combustion converts the internal energy release of an object into heat.

I think it's heat, because the combustion of matter produces heat, which is emitted outward, and if it's internal energy, it shouldn't work.

Thermal energy cannot be generated or destroyed.