"Changes in the State of Matter in Life and Technology" State of Matter and its Changes PPT Courseware 2

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"Changes in the State of Matter in Life and Technology" State of Matter and its Changes PPT Courseware 2

Pre-study tips

Do you know how the white clouds in the blue sky are formed?

What's the matter with the heavy fog you encountered?

Do you know how dew and frost are formed?

Do you know where rain, snow, frost, and hail come from?

Did you know that water resources on earth are in crisis?

What measures are you going to take to save water in your life?

How does a refrigerator cool? How does refrigeration material circulate?

What damaging effect does Freon, the refrigerating substance in refrigerators, have on the environment? Is there an environmentally friendly refrigerator that can replace it?

How does an air conditioner work? How to install an air conditioner to lower the indoor temperature?

What are the significant achievements of our country’s aerospace technology? Where is the knowledge of changes in the state of matter used in aerospace technology?

physics palace

1. Clouds, rain, snow, fog, frost and other phenomena in nature are all caused by changes in the physical state of water.

Dew occurs when the water vapor in the air encounters cooler leaves, flowers and plants before early morning when the weather is hot, and liquefies into small water droplets that adhere to their surfaces. This is a liquefaction phenomenon.

The situation of fog and clouds is the same. Both water vapor liquefies into small water droplets when it is cooled in the air. These small water droplets are suspended in the air and are called fog near the ground and clouds at high altitudes. Therefore, fog and clouds They are all liquefaction phenomena of water vapor, not sublimation of ice.

Frost and snow are both the condensation of water vapor rather than the solidification of liquid.

Frost is water vapor on the ground surface that condenses directly into a solid state at temperatures below zero degrees Celsius.

Snow occurs when the weather is cold and the temperature in the air is below zero degrees Celsius. Water vapor condenses into a solid state in the air and becomes hexagonal ice crystals (or snowflakes), which combine with each other to form snow flakes or snow clumps as they fall.

Hail is an ice ball, and its formation is complicated. Water droplets in the cloud are carried by updrafts to high altitudes where the temperature is below 0°C, and condense into small ice droplets. When the small ice droplets fall, their outer layers are heated and melt into water, and Combining with each other, the ice beads become larger and larger. If the updraft is strong, they will rise to high altitude and condense a layer of ice shell on their surface. After many times of up and down rolling, they can combine into larger ice beads. When they rise, When the airflow cannot support it, the ice beads fall to the ground and form hailstones.

[Example 1] The weather forecast says that there is a weak cold air from the north moving southward, and there will be a light rain in the Pearl River Delta. The reason why the meteorological station said this is ( )

A. There is a large amount of water vapor lingering in the local warm and humid air flow. The water vapor quickly liquefies when it encounters cold air, forming rainfall.

B. There is a large amount of water vapor in the cold air. When it encounters the warm and humid air flow lingering in the local area, it quickly liquefies and forms rainfall.

C. The cold air blows the rainfall clouds from the north to the south

D. It is always going to rain in the Pearl River Delta, and it has nothing to do with the arrival of cold air.

3. Water resources and water resources protection

(1) Freshwater resources: The earth is a water ball, of which more than 97.2% is salt water in the ocean. Only less than 0.03% of the freshwater that humans can actually use directly makes water resources very precious;

(2) Water pollution: divided into two categories: one is natural pollution; the other is man-made pollution. According to different pollution impurities, it is divided into three categories: chemical pollution, physical pollution and biological pollution;

(3) Make rational use of water resources and cherish every drop of water.

We must take more care of precious water resources. In this way, not only do we have water for ourselves, but our future generations will also have water for use. As shown in the picture

4. Physical changes in the family

(1) Pressure cooker

① The reason why the pressure cooker makes food easier to cook: Because the evaporated water vapor remains in the pot, increasing the air pressure above the liquid level, the boiling point of water is higher than 100°C, and food is easy to cook when the temperature is above 100°C;

②Safety devices of the pressure cooker: First, the safety valve. When the air pressure in the pot exceeds the specified pressure value, the air pressure lifts up the safety valve to maintain the air pressure in the pot at a certain value; the second is the fusible sheet. It is made of an alloy with a low melting point. Once the safety valve fails and the temperature in the pot reaches the melting point of the fusible piece, the gas in the pot will be ejected from the fusible piece to prevent explosion accidents;

(2) Refrigerator

Refrigerator working cycle

[Example 3] Air conditioners and refrigerators have entered our homes. May I ask:

(1) Are the cooling principles of air conditioners and refrigerators the same?

(2) When installing an air conditioner, why is it installed above?

(1) The two refrigeration principles are the same. The air conditioner sends the indoor heat to the outside, and the refrigerator sends the heat in the box to the outside.

(2) This will cause the temperature above to be lower than below, which is conducive to using air convection to lower the indoor temperature.

5. Physical state changes in aerospace technology

(1) Liquefaction: The fuel of launch vehicles is often in a liquid state. It is formed by liquefying the gaseous state by compressing the volume. The liquid state is conducive to the storage and storage of a larger amount of fuel, as shown in the figure:

(2) Melting, vaporization and heat absorption: When the satellite returns to the ground, it rubs against the air and the temperature rises. The ablation layer on the fairing will melt, vaporize and absorb a large amount of heat, protecting the rocket or satellite;

(3) Use heat pipes to make the temperature changes uniformly on different surfaces of the satellite.

[Example 5] Water evaporates into the atmosphere and becomes water vapor. The air's capacity for water vapor has a certain limit. The maximum capacity for water vapor is 9g at 10°C, 17g at 20°C, and 30g at 30°C. When the air no longer holds water vapor, It becomes a saturated state. If the temperature continues to drop at this time, will precipitation be possible? Give reasons?

The answer is not necessarily precipitation. Because precipitation must meet three conditions at the same time. Since there may not be condensation nuclei of water vapor in the air, even if the water vapor in the air is saturated and the temperature continues to decrease, the water vapor may not necessarily form small water droplets, that is, clouds and fog. If If the water droplets are not large enough, they will float with the air currents, so precipitation may not necessarily occur.

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"Changes in the State of Matter in Life and Technology" State of Matter and its Changes PPT Courseware 5:

"Changes in the State of Matter in Life and Technology" State of Matter and its Changes PPT Courseware 5 1. Water Cycle in Nature Clouds, rain, snow, fog, dew, and frost are very common natural phenomena, and they are all occurrences of water on the earth. Formed by changes in physical state. Fog is water vapor in the air..

"Changes in the State of Matter in Life and Technology" State of Matter and its Changes PPT Courseware 4:

"Changes in the State of Matter in Life and Technology" State of Matter and Its Changes PPT Courseware 4 [Observe] The existence form of water in nature, and recall the formation process. Ice, snow, rain, dew, clouds, fog, frost, hail [Exploration] 1. The formation of clouds Clouds: water vapor condenses into small ice crystals or liquefies..

"Changes in the State of Matter in Life and Technology" State of Matter and its Changes PPT Courseware 3:

"Changes in the State of Matter in Life and Technology" State of Matter and its Changes PPT Courseware 3 Changes in the State of Matter in Life and Technology 1. The cycle of water in nature. The formation process of rain, snow, dew, and frost. 2. Working principle of pressure cooker. 3. Working principle of refrigerator. The shape of rain...

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Update Time: 2024-10-03

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