What is the essential difference between physical change and chemical change

The essential difference between physical change and chemical change is whether or not a new substance is created.

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

with sufficient energy and.

Correct orientation.

Physical change refers to the fact that although the state of matter has changed, generally speaking, the composition of the substance itself has not changed. For example, changes in position, volume, shape, temperature, pressure, and conversion between gaseous, liquid, and solid states.

There are also the interaction between matter and electromagnetic fields, the interaction between light and matter, and the interaction and transformation between microscopic particles (electrons, atomic nuclei, elementary particles, etc.), all of which are physical changes.

Physical properties: color, state, odor, hardness, magnetism, density, melting point, boiling point, solubility, freezing point, thermal conductivity, electrical conductivity, elongation, volatility, water absorption, soluble in water, etc.

The essential difference between chemical change and physical change is: the property of physical change that does not need to occur for chemical change to manifest directly; The properties of chemically changing substances that are exhibited in chemical changes.

The physical properties of the change of matter: such as color, state, odor, melting point, boiling point, hardness, etc.

Chemical properties of material changes: refers to the unique properties of substances, and different substances have different properties, which are the internal causes of change. The change of matter is a process, which is an orderly, dynamic, concrete embodiment of nature.

Extended Materials. Examples of chemical changes:

Chemical changes are often accompanied by light, heat, gas, precipitation or color and odor changes, and these phenomena can be referred to to determine whether chemical reactions occur. Chemical reactions can also be classified from other perspectives, such as redox reactions and non-redox reactions; endothermic reaction vs. exothermic reaction and so on.

Examples of physical changes:

The basic three-state change of matter, and no new substance is produced, so it belongs to physical change. Deliquescence of inorganic salts and alkalis such as NAOH, melting of ice, crushing of bile alum, etc.

References: Encyclopedia - Chemical Changes.

Encyclopedia - Physical Changes.

Physical change. Chemical changes.

Fundamental differences. There is no change in the formation of new matter (macroscopic).

There is no change in the molecule itself (microscopic).

It's just a change between shape and tristate.

A change in the formation of a new substance (macroscopic).

The molecule itself changes, becoming the molecular (microscopic) relationship of other substances. Chemical changes in matter are often accompanied by physical changes.

A physical change does not necessarily occur when a substance undergoes a physical change.

Whether there is a new substance or not, there is a chemical change that is produced by the new substance, and what is not produced is a physical change, which is what the chemistry books say.

A chemical change is a change in the formation of new substances, such as zinc reacts with hydrochloric acid to form zinc chloride and hydrogen. The formation of new substances, zinc chloride and hydrogen, is a chemical change. Then there is the formation of rust in water, and the main component of rust is iron trioxide, which is a chemical change.

Physical changes do not create new matter, but only a change in the state of matter.

For example, water freezes or turns into water vapor. It's just that the state of water has a liquid that becomes a solid or gas, which is a physical change.

Whether new substances are generated, no new substances are produced by physical changes, and new substances are generated by chemical changes.

Difference Between Chemical Change and Physical Change.

The difference between a physical change and a chemical change is whether or not a new substance is formed.

Connection: There must be physical changes in the process of chemical change, and the process of physical change may be accompanied by chemical change.

Physical Change: No change in the formation of other matter. For example: a light bulb glows, ice melts into water; Water evaporates into water vapor; Iodine, sublimation of dry ice, volatilization of gasoline, melting of wax candles, etc., are all physical changes.

Chemical change: The change in the formation of other substances when the hail retardant changes.

For example: wood burns, iron rusts, food rots.

Chemical changes are often accompanied by some reaction phenomena while generating new substances, such as color changes, gas release, precipitation, etc., chemical changes not only generate other substances, but also accompanied by energy changes, which are often manifested as endothermy, exothermic, luminescence, etc.

Chemical change is prevalent in production and life. The change that produces 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.

Main Differences Between Chemical Change and Physical Change:

The only sign of physical and chemical change is the formation of new substances.

The main connection between chemical change and physical change:

Chemical changes must be accompanied by physical changes.

No new matter is formed when the physical change occurs. Such as ore crushing, but the shape of the substance changes. The smelting of ore into iron is a chemical change because of iron ore.

The main component is the oxide of iron, and the iron produced is elemental, and new substances are generated.

Chemical changes must be accompanied by physical changes. For example, a candle must be melted before it is burned, and then it turns into paraffin vapor. This process is a physical change. Candle burning is a chemical change, and when a physical change occurs, there is not necessarily a chemical change.

From the perspective of molecular atoms, the distance between atoms of physical change changes. For example, when the spacing between the molecules in a solid state becomes larger, the thermal motion intensifies, and it becomes a liquid state.

I continue to heat the atomic spacing and continue to expand and become the essence atom) The constitution is subject to change. Whereas, chemical change is the chemical bond between atoms.

Breakage and recombination into new molecules, regardless of the spacing between molecules.

One of the differences between your change and chemical change is that the physical change does not produce new substances, but the chemical changes produce new substances, and this should be the most essential difference.

There is an essential difference between the changes in physics and the changes in chemistry, and the changes in physics are some changes in appearance, and the essence is unchanged.

The essential difference between physical change and chemical change lies in the presence or absence of new substances.

1. Physical change refers to the process of change in which no new matter is generated. A mixture of pure substances into a mixture is a physical change; The separation of a pure substance from the mixture is also a physical change.

2. Concept: There is no change in the generation of new substance. (Physical change is simply a change in the shape and state of matter).

3. Substance: The smallest particle itself that maintains the chemical properties of the substance remains unchanged, but the interval motion between the particles changes, and no new substance is generated.

4. Many students will confuse physical change with chemical change, in fact, the fundamental difference between physical change and chemical change is that no new substance is formed in physical change, while chemical change is (for example, the process of copper forming patina is chemical change).

5. Macroscopic: no new matter is generated.

6. Microscopic: the distance between the molecule atoms does not change, the shape and size of the substance changes, the molecule itself does not change, and the combination mode of the atoms does not change.

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

8. The process of chemical change is always accompanied by physical change. 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

It has enough energy. 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.