The formation and hazards are physical or chemical changes

It is a chemical change, and the steel is made by oxidizing and removing impurities (carbon, silicon, boron) and other impurities in iron by oxygen in the air to increase the flexibility of steel. Water electrolysis is a chemical change that occurs in which water is electrolyzed to produce hydrogen and oxygen. Chemistry:

The process by which molecules break down into atoms, and the atoms rearrange and combine to form new substances, is called a chemical reaction. In the reaction, it is often accompanied by luminescence, heat, discoloration, and the formation of precipitate, etc., and the basis for judging whether a reaction is a chemical reaction is whether the reaction generates new substances. The process of electrolysis of water (H2O) by direct current to produce hydrogen and oxygen is called water electrolysis, when the current passes through water (H2O), hydrogen is formed by reducing water at the cathode, and oxygen (O2) is formed by oxidizing water at the anode, and the amount of hydrogen generated is about twice that of oxygen, and water electrolysis is the next generation of hydrogen fuel preparation method to replace steam reforming to produce hydrogen.

A physical change is a change in which no new substances are formed, and a chemical change is a change in the production of new substances, also known as chemical reactions. 1. Physical change is simply a change in the shape and state of the substance. Substance:

The smallest particle that maintains the chemical properties of the substance itself remains unchanged, except that the spaced motion between the particles changes, and no new matter is generated. Macro: No new matter is generated.

Microscopic: The distance between the atoms that make up the molecule does not change (the length of the chemical bond does not change), the shape and size of the substance changes, the molecule itself does not change, and the way the atoms combine does not change. 2. The essence of chemical change:

There is no change in the type and number of atoms before and after the chemical reaction, but only the way the atoms bond with each other changes. 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 a substance can only be expressed through chemical changes in the substance, so the chemical properties of the substance can be studied by the method of making the substance react chemically and a new substance can be prepared.

The only difference between a physical change and a chemical change is whether or not a new substance is formed. No new matter is formed when a physical change occurs, e.g. ore crushing is just a change in the shape of the matter. The smelting of ore into iron is a chemical change, because the main component of iron ore is the oxide of iron, and the iron smelted is elemental, and new substances are generated.

Physical deskinning refers to the change that the molecular structure and chemical properties of a substance have not changed after undergoing a change process. The physical change of matter usually only involves the change of external properties, such as the change of shape, size, color, state, etc. Physical change can be reversible, i.e., the substance can be restored to its original state, or it can be irreversible, i.e., it cannot be restored to its original state.

For example, the change of water from a liquid state to ice or evaporation into water vapor is a physical change because the molecular structure and chemical properties of water do not change.

Chemical change refers to the fundamental change in the molecular structure and chemical properties of a substance after undergoing a change process. Chemical change involves the formation, breakage, or recombination of chemical bonds between the molecules of a substance. In chemical change, the structure between the atoms of a substance is altered, resulting in a fundamental change in the properties of the substance.

Chemical change is irreversible, i.e., it is impossible to restore a substance to its original state. For example, when wood is burned, the flames and ashes produced are substances that are produced after the wood undergoes a chemical change because of the change in the molecular structure and chemical properties of the wood.

To sum up, physical change refers to the change of external properties such as form and state of matter, while chemical change refers to the fundamental change of molecular structure and chemical properties of matter. The difference between the two is whether there is a change at the atomic or molecular level involved. Physical change is reversible, whereas chemical change is irreversible.

Understanding physical and chemical changes helps us better understand the properties and change processes of matter, which is of great significance for scientific research and practical applications in various fields.

1. The scale in the kettle is caused by calcium carbonate deposition;

2. The rust in the iron pot is ferric oxide and ferric oxide deposits;

3. The dirt in the toilet bowl is calcium carbonate;

4. The combustion of materials such as paper or wood produces water and carbon dioxide;

5. Iron rust produces rust.

Chemically, changes that produce other substances are called chemical changes. Chemical changes are characterized by the formation of other substances, often accompanied by color changes, precipitation, gas production, endothermy, exothermics, luminescence and other phenomena.

Macro speaking.

is whether there is any new substance produced.

If so, it is a chemical change.

It's been n years since I memorized it.

The difference between physical change and chemical change is simple: see if anything new is formed!

The reaction in which a new substance is formed is called a chemical change, also called a chemical reaction!

A reaction without the production of sexual substances is a physical change! (These two sentences are my own understanding, but the definition of physical change is not so, so this can help you understand the difference).

Iron rust is iron turned into iron oxide! New matter is generated!

There are also many examples of physical change: physical change refers to the change in the physical properties of a substance that only changes its physical properties (e.g., aggregation state, density, solubility, conductivity, etc.), but does not change the chemical composition and chemical properties of its molecules (or crystals).

The following is an example of a physical change:

1 Water evaporates and solidifies 2 Sugar cubes melt 3 Carbon dioxide condenses into dry ice 4 Iodine sublimates into purple vapor when heated 5 Flour clumps after a long time 6 Glass softens 7 Mirrors crack 8 Trees are cut down 9 Paint dries out 10 Paper towels crumple up 11 Dust is swept together 12 Plasticine is kneaded 13 Wooden sticks are broken 14 Rice is chewed fine during meals 15 Popsicles are turned into popsicles and so on.

Difference Between Chemical Change and Physical Change.

The difference is whether or not new matter is generated. What is produced by a new substance is a chemical change, and what is generated without a new substance is a physical change. From a microscopic point of view, it is whether the atoms have combined to form new molecules or ions.

Analysis: The essential difference between physical change and chemical change is whether new substances are generated before and after the change: new substances are generated as chemical changes; No new matter is generated into physical changes.

When there is a new substance, there is a chemical change, a physical change, such as a car tire burst, cutting vegetables.

Break a piece of chalk because no new substance is generated.

A chemical change is the formation of a new substance. It is different from physical change.

Physical change, water becomes water vapor. It is still a component of water. Water vapor is not a new substance. It is caused by changing the temperature and causing the state to be different.