Wonderful change of state of matter 20, the phenomenon of change of state of matter

Change of state of matter: In physics, we call the process of change of matter from one state to another as a change in the state of matter. There are 6 variations, including melting, solidification, vaporization, liquefaction, sublimation, and condensation.

Introduction to the change of state of matter:

The first is the solid state and liquid state of the substance, the relationship between the two, when the substance is converted from the solid state to the liquid state, this phenomenon is called melting, and the melting should be endothermic, such as ice absorbing heat and melting into water, on the contrary, when the substance is converted from a liquid state to a solid state, this phenomenon is called solidification, and solidification should be exothermic, such as water being exothermic and solidified into ice.

The crystals have a melting point, that is, when the temperature reaches the melting point (continuous endothermy), the temperature will melt when it reaches the melting point, and the temperature will always be equal to the melting point when melting, and the temperature will rise after complete melting. Amorphous does not have a fixed melting point, so the temperature during the melting process is uncertain, such as the temperature of paraffin wax during the melting process. When the crystal melts, the temperature does not change, and there are three states.

Then there is the change relationship between the gaseous state and the liquid state of the substance, the substance is converted from the liquid state to the gaseous state, this phenomenon is called vaporization, and vaporization has two ways: evaporation and boiling, evaporation occurs on the surface of the liquid, which can be carried out at any temperature, which is slow. Boiling occurs on the surface and inside the liquid and must reach the boiling point and is violent.

Vaporization has to absorb heat, the liquid has a boiling point, when the temperature reaches the boiling point, the temperature will not rise again, but it is still absorbing heat; When a substance is converted from a gaseous state to a liquid state, this phenomenon is called liquefaction, and liquefaction requires exothermy. For example, water vapor liquefies into water, and water evaporates into water vapor.

Finally, the relationship between the solid state and the gaseous state of the substance, which is not common to us, the direct conversion of the substance from the solid state to the gaseous state, this phenomenon is called sublimation, and the common sublimable substances in life are dry ice, mothballs, etc. Then there is the direct conversion of matter from the gaseous state to the solid state, which is called condensation. Sublimation endothermy (if you want to sublimate a solid, you can't let that solid reach its melting point, otherwise it will melt first and then vaporize), condensation and exothermy.

1 Water droplets (melting) dripping from sorbet in summer

2 Ice particles turn into raindrops and fall (melt).

3 When building asphalt roads, use large melting stoves to melt asphalt (melt).

4 Ice is placed in the sun and becomes water (melting) in a while5 Steel is placed in a steelmaking furnace and becomes molten steel (melting)6 Pure water condenses and forms ice cubes (solidification).

7. Molten steel is cast into wheels (solidified).

8 Icicles (solidification) formed on power poles during a snowstorm

9 Molten steel is burned and cast into a train wheel (solidified).

10 Volcanic eruptions (first melt and then solidify).

11 In autumn, the morning fog dissipates after the sun comes out (vaporization - evaporation)12 The water sprinkled on the ground is gone (vaporization - evaporation)13 The alcohol rubbed on the ** dries up immediately (vaporization - evaporation)14 The body feels cold after swimming ashore (vaporization - evaporation)15 Boil a pot of water (vaporization - boiling).

16 In the summer, "white gas" (liquefaction) rises around popsicles

17 In the summer, the outer layer of the tank "sweats" (liquefies).

18. In the morning, small water droplets (liquefaction) on grass and trees

19 The morning fog and dew (liquefaction).

20 In the summer, the drink can taken out of the refrigerator "sweats" (liquefies) 21. After taking a hot bath, the glass in the bathroom becomes blurry, and after a while it becomes clear again (liquefied first and then vaporized).

22. Boil water with an electric water heater, and "white steam" constantly emerges when boiling (first vaporized and then liquefied) 23. Iodine is heated at high temperature, and the volume of iodine becomes smaller (sublimated).

24 The mothballs in the suitcase gradually become smaller (sublimated).

25 In winter, clothes that are frozen outside also dry (sublimated).

26 In the cold winter, the snowmen built became smaller (sublimated).

27 Filament (tungsten) thinning (sublimation).

28 Dry ice (solid carbon dioxide) is used to artificially rain (sublimation)29 In winter, ice (or "window flowers") (condensation) form on the inner surface of glass windows30 A layer of frost forms on the roof tiles (condensation).

31 The trees hang in the winter in the north

32 The fog (condensation) seen in the southern snowstorm

33 The bulb (tungsten filament) is blackened (Ninghua).

34 "White powder" (condensation) found in ice cream paper

35 Dry ice (solid carbon dioxide) is used to create a wonderful stage effect (first sublimation and then liquefaction)36 Formation of rain: vaporization (or evaporation) liquefaction solidification and melting; Vaporization (or evaporation) of condensation melting.

Vaporization (or evaporation) liquefaction.

Three major names for water:

Solid: Ice (solidification), frost (condensation), snow (condensation), rime, "window flower" (condensation), hail (condensation), white ice.

Liquid state: water, dew (liquefaction), rain (liquefaction), fog (liquefaction), "white gas" (liquefaction) gaseous state: water vapor [Note: Water vapor is not visible, what is visible is the water droplets formed by the liquefaction of water vapor. 】

Junior High School Physics: The phenomenon of change in the state of matter in life.

1. Read proverbs and explain the changes in the state of matter.

1.Snow falls on the mountains, frost falls on the plains.

Answer: On snowy days, the temperature in the mountains is lower than the temperature in the flatlands below, and the snow down to the mountains is not easy to melt, while the snow down to the flatlands is easy to melt in time. So for the same snow, there is more in the mountains than on the flats.

Frost is the result of water vapor on the ground meeting condensation, and there is more water vapor on the surface of the flat land below the mountain than on the high mountain, so the flat land is easy to form frost, while the high mountain is not easy to form frost.

2.The water tank sweats, so you don't have to carry the burden (if you wear a skirt on the water tank, it will rain).

Answer: Due to the evaporation of the water in the tank, the temperature of the part below the water surface is lower than the air temperature, and the water vapor in the air meets the outer surface of the tank with a lower temperature, and the water droplets are attached to the outside of the water tank. On sunny days, due to the low water vapor content in the air, although the water vapor will also liquefy on the outer surface of the tank, the trace amount of liquefaction will quickly evaporate and cannot form water droplets.

If the air is humid, the evaporation of water is very slow, the liquefaction of the outer surface of the water tank is greater than the vaporization of Nianyan, there are water droplets, the content of water vapor in the air is large, and the possibility of rainfall is large, of course, there is no need to carry water to water the ground.

3.Boiling water does not sound, ringing water does not boil.

Answer: Because the bubbles in the water will make a sound when boiling water, the faster the bubbles rise, the louder the sound, the speed of the bubbles rising is related to the temperature difference between the water at the bottom of the kettle and the water on the surface, the larger the temperature difference, the faster the bubbles rise. When Tsai Li Yin began to boil water, the temperature of the water touching the bottom of the pot was high, the water temperature on the surface was low, the temperature difference was large, and the bubbles rose quickly, so "the water did not open".

When the water boils, the temperature of the water at the bottom of the pot is basically the same as the water on the surface, and the bubbles in the water rise slowly, so "the boiling water does not make a sound".

4.Freezing three feet, not a day's cold.

Answer: Freezing is the solidification phenomenon of water, and the temperature of water between 0 and 4 is abnormal expansion, that is, heat shrinkage and cold expansion. In winter, when the temperature drops, the temperature of the upper river water is lower and the density is higher, so it will sink, and the temperature of the bottom water is high and the density is smaller, so it will rise, forming a convection current, so that the whole river water is constantly cooled.

When the temperature of the entire river drops to 4, the convection stops. When the temperature continues to drop, the temperature of the upper river water continues to drop, and the temperature of the bottom water remains 4. When the temperature of the upper river drops to 0 and continues to release heat, the river surface begins to freeze.

Since then, because water and ice are poor conductors of heat, and the smooth and bright ice surface can prevent radiation, therefore, the three ways of heat transfer are not easy to carry out, and the water under the ice is extremely slow to release heat, and it takes a long time to form thick ice, so there is a saying that "freezing three feet, not a day's cold".

5.The snow is not cold, the snow is cold.

Answer: Snow is formed by the condensation of water vapor or small water droplets in the air, and since both condensation and coagulation are exothermic processes, it does not feel cold, whereas snow melting is an endothermic process, so it feels cold.

6.It's cold before frost and cold after snow.

Answer: The formation of frost is a process of condensation, and condensation is an exothermic process, so the temperature before frost must be very low, so that the water vapor in the air can be exothermic and condense to form frost; When snow falls, it absorbs a lot of heat during the melting and sublimation of the snow, so when it snows, the outside temperature will be very low.

Lack of things in junior high school: the phenomenon of the state of things in life and the phenomenon of changing the shape of the family.

Change of state of matter: In physics, the process of changing matter from one state to another is called change of state of matter.

Brief description of the process of state of matter: In middle school physics, three kinds of state changes are studied, and they can be transformed into each other in pairs: melting, solidifying, vaporizing, liquefiing, sublimation, and condensation.

The key to determining what kind of change of state of matter occurred is to find the two states of matter before and after the change in state of matter, and then compare them according to the definition, so that you can draw the correct conclusion.

Separation and heat absorption (release) of state change:

Melting: Solid liquid state (endothermy).

Coagulation: Liquid solid state (exothermic).

Vaporization: Liquid gaseous (endothermic).

Liquefaction: gaseous liquid (exothermic).

Sublimation: Solid gaseous state (endothermic).

Condensation: Gaseous solid state (exothermic).

I hope it helps you, and if you have any questions, you can ask them

I wish you progress in your studies and go to the next level! (*

In summer, "dewdrops" are formed on grass blades, which are small droplets of water vapor in the air that liquefy into a liquid state when cold, which are attached to the surface of vegetation, which is a liquefaction phenomenon.

In winter, the "ice flower" on the window is the water vapor with high indoor temperature meets the cold glass, and the condensation phenomenon occurs on the inner surface, forming Xiaoice crystals, which belongs to the condensation phenomenon;

In late autumn, the hoarfrost on the tree is formed by the water vapor in the air directly turning into Xiaoice crystals when it is cold, which belongs to the phenomenon of condensation;

In early spring, the melting of ice and snow is the process of changing the substance from a solid state to a liquid state, which belongs to the melting phenomenon The change of the state of matter is the same group as Zhifeng

Therefore, C

The solid absorbs heat and melts into a liquid, and the solid absorbs heat.

The liquid absorbs heat and vaporizes into a gas, and the liquid absorbs heat.

Solid endothermic sublimation into gas, solid endothermy.

The gas is exothermic and liquefied into a liquid, and the gas is exothermic.

The liquid releases heat and solidifies into a solid, and the liquid releases heat.

The gas is exothermic and condenses into a solid, and the gas is exothermic.

The solid absorbs heat and melts into a liquid. The liquid is endothermic and vaporized into gas. The gas emits heat and liquefies into a liquid. The liquid emits heat and solidifies into a solid. Solids are endothermic and sublimated into gases. The gas is exothermic and condenses into a solid.

Liquid, liquefaction, condensation, solidification, exothermic are gases, gases, and liquids are exothermic, respectively.

Sublimation, melting. endothermic, solid, solid, respectively.