What is the conversion of energy in chemical change

Chemical changes are not only manifested in the formation of new matter, but also in the form of changes in energy, which are often manifested in the release and absorption of heat, light, and electrical energy.

It's notChemical reactionsIt must be accompanied by a change in energy, and a process with a change in energy is not necessarily a chemical change processFor example, by water vapor.

When it becomes water, heat is released, accompanied by a change in energy, but this change is a physical change.

A change in a new substance is a chemical change. Such as the rust of iron, the fireworks of festivals, the neutralization of acid and alkali, the burning of magnesium strips, and so on. On a macroscopic scale, it can be seen that various chemical changes produce new substances, which is characteristic of chemical changes.

Summary: A change in a new substance is a chemical change.

Characteristics of chemical changes.

The essence of chemical change can be understood from a microscopic perspective: the type and number of atoms before and after a chemical reaction do not change, but only the way of bonding between atoms has changed, and atoms are the smallest particles of chemical change. For example, in the case of a substance made up of molecules, it is a molecule in which atoms are recombined into a new substance.

The chemical properties of the substance.

It can only be manifested by chemical changes in substances, so it is possible to study the chemical properties of substances and make new substances by using methods that cause chemical reactions in substances.

Chemical reactionsThe main forms of change in the residual capacity of the medium energy:

Chemical energy vs thermal energy.

Chemical energy and electrical energy of skin destruction mode.

Chemical energy vs light energy.

The reason for the energy conversion of chemical reactions: The essence of chemical reactions is the chemical bonds in the reactant molecules.

Breakage, the process of forming new chemical bonds The breaking of old bonds requires the absorption of slow energy, and the formation of new bonds requires the release of energy.

In general chemical reactions, the total energy absorbed by the breaking of the old bond is not equal to the total energy released by the formation of the new bond, and this difference is the change of energy in the reaction, so there will be a change in energy during the chemical reaction.

In electrochemistry, chemical energy is converted into electrical energy, in thermochemistry, chemical energy is converted into internal energy, which is transferred in the form of heat, and in biochemical reactions, biological energy is converted into chemical energy, which is eventually lost in the form of heat.

There are many of them, and the most common ones are heat, light, electricity, and so on.

Chemical energy is converted into heat energy and light energy.

Systematically speaking, there are only two forms of all energy changes, that is, work and heat, heat has nothing to say, there is more work, including volumetric work and non-volumetric work, volumetric work is used to change the volume to do work, such as the increase or decrease of gas, the volume changes, it is necessary to overcome the external force to do work, non-volumetric work such as electrical work, potential energy and so on.

There are thermal changes in energy changes in chemical reactions: endothermic reactions and exothermic reactions. heat of combustion and heat of neutralization; Heat of combustion:

At 101 kPa, 1 mol of combustibles is completely burned to form a stable oxide. Heat of neutralization: In a dilute solution, the heat of reaction when the neutralization reaction of acid and base occurs to produce 1mol of water.

The relationship between the change of the gas, liquid, and solid states of a substance and the heat of reaction.

Chemically, the chemical reaction that eventually manifests itself as absorbing heat is called an endothermic reaction. The total energy of the reactants in an endothermic reaction is lower than the total energy of the products.

The reverse reaction of an endothermic reaction must be an exothermic reaction.

The stronger the energy (bond energy) of the chemical bond in the product, the stronger the stability; The weaker the bond energy, the worse the stability.

For example: C+H2O=(High Temperature) CO+H2

The decomposition reaction is generally an endothermic reaction, such as 2NaHCO3 (heating) Na2CO3+H2O+CO2.

Note: Reactions that do not require heating are endothermic reactions, and most of the combustion reactions are "ignited", which are exothermic reactions.

A chemical reaction in which the total energy before the reaction is greater than the total energy after the reaction is called an exothermic reaction

Common exothermic reactions:

1) All combustion or ** reactions.

For example, CH4+2 O2=CO2+2 H2O

ch2s+6 f2=cf4+2 hf+sf6

2) Acid-base neutralization reaction.

3) Most chemical reactions.

For example, C+CO2=2CO

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

5) Many redox reactions (but not absolute). Typical exothermic reactions such as hydrogen, charcoal or carbon monoxide to copper oxide are typical.

Chemical energy can usually be converted into heat, light, mechanical, electrical, etc.

1. Conversion of chemical energy into heat energy

All exothermic reactions, such as the combustion of coal, release heat and provide energy.

2. Conversion of chemical energy into light energy

Luminescent combustion reactions, such as magnesium combustion, emit a dazzling white light.

3. Chemical energy is converted into mechanical energy: such as explosives**.

4. Conversion of chemical energy into electrical energy

The principle of galvanic battery, the process of battery discharge is the conversion of chemical energy into electrical energy, such as lead-acid batteries.

Thermal energy, light energy, electrical energy, combustion and luminescence are the first two, and the redox reaction is designed into a galvanic cell.

Such as electrical energy, batteries are examples, such as heat energy, the reaction of quicklime and water

Chemical change refers to the process of conversion or transfer of atoms or electrons between molecules in contact with each other to form new molecules accompanied by changes in energy, which is essentially the breaking of old bonds and the formation of new bonds.

Chemical changes are always accompanied by physical changes. In the process of chemical change, there are usually luminescence, exothermia, and endothermy. According to the atomic collision theory, the chemical change between molecules is accomplished through collision, and two conditions need to be met to complete the collision of the molecule that reacts

1) Have sufficient energy; (2) Correct orientation. Because the reaction needs to overcome a certain molecular energy barrier, it must have a higher energy to overcome the molecular energy barrier. Two colliding molecules must have the correct orientation for the old bond to break.

Energy changes. From the perspective of the energy change of the reaction, it can be divided into endothermic reaction and exothermic reaction.

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. These include combustion, neutralization, metal oxidation, thermite reactions, more reactive metal reactions with acids, and reactions from unstable substances to stable substances.

Endothermic reaction refers to a chemical reaction that is chemically characterized by the absorption of heat. The total energy of the reactants in an endothermic reaction is lower than the total energy of the products. The reverse reaction of an endothermic reaction must be an exothermic reaction.

Because the chemical change is essentially the breaking and reconnection of the chemical bonds. Breaking a bond requires absorbing energy, and bonding requires the release of energy. So there will be a change in energy.

Change in energy in a chemical reaction: The change in the heat of a chemical reaction.

Exothermic or endothermic is often a specific manifestation of energy changes in chemical reactions. A chemical reaction is said to be exothermic if it is in progress and simultaneously supplies energy to the environment (usually in the form of heat); Conversely, if a chemical reaction absorbs energy from the environment at the same time, the reaction is called an endothermic reaction.

Sometimes, the change in energy in a chemical reaction is also expressed in the form of light energy. For example, the combustion process simultaneously emits light (a form of energy), and some reactions can only take place under the irradiation of light, such as photographic film.

There are also chemical reactions that manifest themselves in the form of electromagnetic energy, called electrochemical reactions. The most common limb orange bend is the chemical battery Wu Da.