"Changes in the State of Matter in Life and Technology" PPT courseware on the state of matter and its changes

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"Changes in the State of Matter in Life and Technology" PPT courseware on the state of matter and its changes

[Experience] Physical changes in life

Activity 1: Eating ice cream makes people feel very cool;

Activity 2: The water sprinkled on the indoor floor "disappears" after a while, and people feel that the room is cooler;

(1) In activity 1, people feel cool because of the ice cream ________.

(2) People in activity 2 felt cool because the water ________.

Tips: (1) Melting endotherm (2) Evaporation endothermic

pre-study questions

1. How are clouds, rain, snow, frost, fog, and dew formed?

2.What is the working principle of pressure cooker?

3. What is the working process of a refrigerator?

4. What is the protection method for the rocket return capsule?

Explore changes in physical state in life and technology

1. Combined with the process of water cycle, analyze the physical state changes involved in the formation of clouds, rain, snow, fog, and frost in nature.

cloud water → (_____) → water vapor → (_________) → small water droplets or small ice crystals

Rain small water droplets or small ice crystals→(_____)→water droplets

Snow water vapor→(_____)→small ice crystals

Fog (dew) water vapor → (_____) → small water droplets

Frost water vapor→(_____)→small ice crystals

2. What are the applications of changes in the state of matter in life and technology? Please give two examples each.

Tips: When the temperature reaches its melting point, the fusible piece of the pressure cooker continues to absorb heat and melt, and the gas in the pot spurts out, reducing the pressure in the pot and preventing danger. When the weather is hot, sprinkle water indoors to use water evaporation to absorb heat and cool down; the refrigeration substance used in the refrigerator is a substance that is easy to liquefy and vaporize, and the substance can absorb a large amount of heat when vaporized. Application in technology: Doctors use alcohol to evaporate and absorb heat to physically cool patients; the outer layer of the spacecraft return capsule uses polymer materials to melt, evaporate, sublime or decompose and vaporize away a large amount of heat when heated at high temperatures; Heat pipes use liquid to continuously vaporize and liquefy, "transporting" heat from the hot end to the cold end, etc.

Reference answer: Application in life: fusible sheets of pressure cookers, sprinkling water to cool down when the weather is hot; application in technology: doctors use alcohol evaporation to physically cool patients, heat pipes.

Knowledge summary

1. Water cycle in nature

1. Formation

(1) Cloud: It is a concentrated suspension of small water droplets formed by water vapor or small ice crystals formed by _____

Formed at high altitude.

(2) Rain: water vapor _____ into small water droplets or condensed into small ice crystals _____ into small water

The drops fall to the ground and form rain.

(3) Snow and frost: are formed by water vapor _____.

(4) Fog and dew: formed by water vapor _____.

2. Three-state cycle of water (fill in the name of physical state changes and heat absorption and release)

2. Pressure cooker

During operation, due to the increase of water vapor in the pot, the gas pressure above the water surface _____, causing the water to

The boiling point of _____.

Test points: Application of physical state changes in life

[Typical example] People can live for 30 days without food; if there is no water, the time limit is shortened to 3 to 4 days. Therefore, water is the basic element of human life; as shown in the picture is an emergency water purification device. Pour water that cannot be directly drunk (such as muddy water, sea water, etc.) into a large container, place the cup in the center of the container, seal the mouth of the container with plastic film (leave a small gap on the edge of the container), and press a stone on top to make the plastic The membrane forms a concave surface. Place the finished water purifier in the sun, and in a few hours the pure water dripping from the plastic film will be collected in the cup. This kind of water purification device mainly uses the _______ and _______ phenomena to achieve the purpose of water purification.

[Idea Guide] Two key points to answer this question:

Key Point 1: Water changes from liquid to gas when exposed to sunlight.

Key point 2: Water vapor changes from gaseous to liquid when encountering plastic film.

[Intensive Lecture and Analysis] This question tests the understanding of water and the changes in its physical state. The sewage first evaporates (vaporizes) under the sun and turns into water vapor that rises. When it encounters the plastic film, it liquefies into water and drips into the collection cup for collection.

Answer: evaporation (vaporization) liquefaction

1. (2012·Xiamen High School Entrance Examination) The following symbols respectively represent the four phenomena of heavy rain, hail, frost and fog, among which the main ones formed through condensation are ()

[Analysis] Choose C. This question examines the water cycle in nature. Frost is a solid that condenses directly from water vapor in the air when it is cooled. It is a condensation phenomenon. Rain and fog are liquid and are formed by the liquefaction of water vapor in the air when it is cooled. Hail is a solid form of rain that becomes cold when it falls. It is a solidification phenomenon. So choose C.

2. (2012·Chongqing High School Entrance Examination) Water shortage is a worldwide problem, so we must cherish every drop of water. In some countries that are seriously short of water, dew is also an important water resource. The formation of dew is part of the change of physical state. ()

A. Melting B. Vaporization C. Liquefaction D. Sublimation

[Analysis] Choose C. This question examines the phenomena of physical state changes related to water. Dew is small water droplets formed when water vapor in the air liquefies when cooled. Option C is correct.

3. In the sugar industry, boiling is generally used to remove moisture from sugar juice. However, when heating, you must ensure that the temperature of the sugar juice is below 100°C, otherwise the sugar quality will be affected. To this end, which of the following measures would you recommend? ()

A. Use "simmer" to slowly heat the sugar juice

B. Use "fierce fire" to heat quickly and shorten the heating time

C. Try to increase the air pressure on the sugar juice surface

D. Try to reduce the air pressure on the sugar juice surface

[Analysis] Choose D. This question examines the relationship between boiling point and atmospheric pressure. The boiling point of a liquid is related to the atmospheric pressure. The lower the atmospheric pressure above the liquid, the lower the boiling point of the liquid. Therefore, to reduce the boiling point, the atmospheric pressure must be reduced, so the air pressure on the sugar juice surface should be reduced.

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For more information about the PPT courseware "States of Matter and Changes of Matter in Life and Technology", please click the "States of Matter and Changes of Matter in Life and Technology" PPT courseware.

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Update Time: 2024-11-25

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