Explain the following phenomenon from a molecular point of view 20

1. It is a chemical change. Water molecules are decomposed into hydrogen atoms and oxygen atoms under the action of direct current, hydrogen atoms are recombined into hydrogen molecules, oxygen atoms are recombined into oxygen molecules, and hydrogen molecules and oxygen molecules are aggregated into hydrogen and oxygen, respectively.

2. It is a physical change. The water molecule itself does not change, only the interval between the water molecules decreases.

3. It is a physical change. The carbon dioxide molecule itself does not change, but the interval between the carbon dioxide molecules increases.

4. It is a chemical change. After the food goes bad, the molecules themselves change.

1.It is a chemical change, and the water molecule is energized to produce hydrogen molecules and oxygen molecules.

2.It is a physical change, the water molecules do not change, and the gap between the water molecules becomes larger.

3.It is a physical change, the dry ice molecules do not change, and the gap between the dry ice molecules becomes larger.

4.It is a chemical change, a change in the molecule, and a new molecule is generated.

1.The electric current splits water into oxygen molecules and hydrogen molecules, with hydrogen gathering at the negative electrode and oxygen at the positive electrode.

2.The decrease in temperature causes a change in the molecular structure, and the liquid becomes a solid – the water becomes ice.

3.Carbon dioxide molecules are integrated into a solid state, dry ice, at low temperatures, and the molecular structure is changed by heating at room temperature to a gaseous state.

4.Oxygen molecules undergo a chemical reaction with food molecules – oxidation – that is, oxygen atoms and atoms in food form new molecules to form oxides.

1. Water molecules are decomposed into two atoms, hydrogen and oxygen, and hydrogen-hydrogen and oxygen-oxygen are combined respectively to form hydrogen and oxygen.

2. Molecular arrangement crystallization.

3. Random diffusion of molecules.

4. A chemical reaction occurs.

(1) The sugar cube will dissolve when placed in water, and the liquid level will drop.

There are gaps between the molecules, and when dissolved, some sugar molecules run into the gaps of the water molecules, and some water molecules run into the gaps of the sugar molecules.

2) Wet clothes dry faster in the sun than in the shade.

Molecules are moving irregularly and the higher the temperature, the faster the movement.

There are voids in the sugar cube, and water molecules can enter the middle, and the total volume does not increase after dissolving.

The increase in the temperature of sunlight accelerates the volatilization of water molecules, and wet clothes dry quickly.

1. The molecule is a kind of particle with the chemical properties of the conservatory material, and both liquid oxygen and oxygen contain oxygen molecules, so the chemical fiber properties are the same.

2. There is a trace tremor interval between molecules, which increases when heated and decreases when cold, so it causes changes in the volume of matter.

3. In chemical change, molecules become atoms, and atoms are recombined into new molecules, so matter changes.

1. All solutions: a. Wet clothes can be dried faster under the sun, indicating that the higher the temperature, the faster the movement of molecules, so the explanation is correct;

b. A piece of metal is difficult to be compressed, because the gap between atoms is very small, so the option is wrong;

c. The deflated table tennis ball will return to a spherical shape when put into hot water, because the interval between the gas molecules in the ball increases with the increase of temperature, so the option is wrong;

d. Because there is a relatively large gap between the particles that make up the gas, the gas is easily compressed under pressurized conditions, so the explanation is correct

Therefore, AD is chosen

A. DB is wrong that there is a gap between the molecules, but the gap between the solid molecules is too small, and there is repulsion between the molecules.

c The mistake is not that the molecules become larger, but that the distance between the molecules increases due to heat.

I think ad is correct.

B is wrong because there is a gap between the molecules, and it is difficult to be compressed because of the repulsion between the molecules.

c The error is that the intermolecular gap becomes larger as the temperature increases, not the molecule itself.

Option d is incorrect.

Nothing that can be seen with the naked eye is a molecule.

aBecause the distance between the molecules is too large, they cannot attract each other, that is, they cannot be "reunited".

b. The mutual attraction between the water molecule and the state cup molecule.

The carbon molecules in the carbon doping agent are diffused through the molecules and enter between the molecules of the parts, that is, the hardness of the parts is increased.

d. Use a beaker to hold some dirty water, and many particles can be seen moving constantly in the sun.

1. The molecular interval increases.

2. The constant movement of molecules is caused by diffusion into the air.

3. Molecules are constantly moving.

4. The temperature of the place exposed to the sun is high, the rate of molecular movement is accelerated, 5. The gas is pressurized, and the molecular interval becomes smaller.

6. The mixture is composed of a variety of substances, and the pure substance is composed of the same substance, with a fixed composition, melting point, boiling point, etc.

1 There is a good interval between molecules, and the water evaporates into water vapor, and the interval between molecules becomes larger. 2 molecules are in constant motion, and the floral molecules in the wall are constantly moving to the outside of the wall, so the floral fragrance can be smelled outside the wall. 3. If it is not sealed and stored, the molecules of perfume and gasoline will continue to move into the air.

4. Molecules are in constant motion, and the higher the temperature, the faster the molecules move. There are gaps between 5 molecules. 6 A mixture is a substance composed of a variety of molecules, and a pure substance is a substance composed of the same kind of molecule.

Brownian motion, i.e., the irregular motion of molecules, increases in temperature, and the irregular motion of molecules intensifies2,3,4

6 There is only one substance in purity, and there are many substances in the mixture, such as oxygen is pure, and oxygen plus ozone is a mixture.

1,5 large intervals between gas molecules.

1.The intermolecular distance increases.

2.Molecular kinetic theory, diffusion phenomenon. Molecules are constantly moving in random motion3Molecules are constantly moving randomly.

4.The higher the temperature, the faster the molecules move irregularly5External conditions can forcibly change the molecular spacing; There are gaps between the molecules6A pure substance is a substance that is composed of only one other molecule (atom).

What is the reason why the air is humid in summer and dry in winter?

The temperature in summer is higher than in winter, and the water molecules are easily vaporized, and the air is humid in summer.

Why are the chemical collision properties of water and hydrogen peroxide different?

The molecular composition of water and hydrogen peroxide is different, and the chemical properties of the chemical deficiency are different.

There are about 17 trillion water molecules in a drop of water?

Indicates that the molecule is small.

1. One is a physical change and the other is a chemical change; Therefore, there is no change in the molecule in the volatilization of alcohol, while the combustion of alcohol is a molecular change in the composition, and the atoms are recombined into a new molecule.

2. It is the molecules that are moving.

3. This seems to have nothing to do with molecules and atoms! This is the thermal expansion and contraction of a solid.

Well, the first one is the physical change and the chemical change, there is nothing to say.

The second, Brownian motion ......

Third, molecular kinetic theory ......It's kind of like physical thermodynamics, ah, orz......

2.This is due to the irregular movement of the molecules.