-1, the state of matter: Because a large number of molecules that make up a matter are doing random thermal motion endlessly, different molecules do thermal motion at different speeds, thus forming three states of matter: solid, liquid and gas. In physics, we call the state of matter state. 2. Process of state change (introduction): Because there are three states of matter (actually, there are several, only three are studied here. Other states such as plasma. ), they can be transformed into each other, so there are six state changes (abbreviated as: three States and six changes): melting, solidification, vaporization, liquefaction, sublimation and sublimation (see the following explanation for details). 3. How to judge what kind of state change has taken place: The key is to find the two states of matter before and after the state change, and then compare them according to the definition, so as to draw a correct conclusion.
-Three states, six transformations and heat absorption and release:
Change of state
Melting: solid → liquid (endothermic)
Solidification: liquid → solid (exothermic)
Vaporization: (boiling and evaporation): liquid → gas (endothermic)
Liquefaction: (two methods of compressing volume and lowering temperature): gas → liquid (exothermic)
Sublimation: solid → gas (endothermic)
Condensation: gas → solid (exothermic)
(Note: The "heat" of "endothermic" and "exothermic" here refers to heat, not thermodynamic concepts such as temperature, internal energy, calorific value and specific heat capacity. It is the abbreviation of "endothermic" and "exothermic". In physics, heat cannot be said to be "how much heat it contains" or "how much heat it has", but only "how much heat it absorbs" or "how much heat it releases".
-1. Water droplets (melting) dropped by sorbet in summer are more physical changes in nature;
2. Ice particles turn into raindrops and fall (melt)
When repairing asphalt road, use melting furnace to melt asphalt.
When ice is placed in the sun, it will become water (melt) in a short time.
Put steel into the steelmaking furnace and it will soon become molten steel.
6. Pure water condenses into ice (solidification)
7. Casting molten steel into wheels (solidification)
During the snowstorm, icicles formed on telephone poles.
9. Molten steel is cast into train wheels (solidified)
10. Volcanic eruption (melting before solidification)
1 1. In autumn, the morning fog disappears after the sun comes out (vaporization-evaporation).
12. The water spilled on the ground disappeared (vaporization-evaporation)
13. The alcohol rubbed on the skin dries immediately (vaporization-evaporation).
14. I feel cold after swimming ashore (evaporation-evaporation)
15. Boil a pot of water (boil by vaporization)
16. In summer, white gas (liquefaction) will be emitted around the popsicle.
17. In summer, the outer layer of the water tank "perspires" (liquefies).
18, in the morning, water droplets on vegetation (liquefied)
19. Fog and dew in the morning (liquefaction)
20. In summer, the beverage cans taken out of the refrigerator will "sweat" (liquefy).
2 1. After taking a hot bath, the glass in the bathroom becomes blurred, and then becomes clear (first liquefied and then vaporized).
22. When the electric water heater is used to boil water, "white steam" is constantly emitted when boiling (first vaporized and then liquefied).
23. When iodine is heated at high temperature, the volume of iodine becomes smaller (sublimated).
24. The mothballs in the suitcase gradually become smaller (sublimated).
25. Clothes frozen outdoors in winter will also dry (sublimate).
26. In the cold winter, the snowman becomes smaller (sublimated).
27. The filament (tungsten filament) is thinned (sublimated)
28. Dry ice (solid carbon dioxide) is used for artificial rainfall (sublimation)
29. In winter, ice flowers (or "window grilles") (sublimation) are formed on the inner surface of glass windows.
30. The tiles on the roof are covered with frost.
3 1. Hanging Trees in Northern Winter (Ninghua)
32. Wusong (Ninghua) in the snowstorm in the south.
33. The light bulb (tungsten wire) is black (Ninghua).
34. "White powder" found in ice cream paper (Ninghua)
35. Dry ice (solid carbon dioxide) is used to create a wonderful stage effect (sublimation before liquefaction).
36. The formation of rain: ① vaporization (or evaporation) → liquefaction → sublimation → melting; ② Vaporization (or evaporation) → Solidification → Melting
③ Vaporization (or evaporation) → liquefaction