"Integration of this Chapter" Changes in Physical State PPT

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"Integration of this Chapter" Changes in Physical State PPT

High School Entrance Examination Focus Experience

1. (2018 Chifeng High School Entrance Examination in Inner Mongolia) Among the following groups of solids, the one with a definite melting point is ()

A. Wax, glass, asphalt B. Wax, aluminum, glass

C.Ice,Iron,Aluminum D.Ice,Iron,Asphalt

Wax, glass, and asphalt are all amorphous and have no fixed melting points, so A, B, and D do not meet the meaning of the question; ice, iron, and aluminum are all crystals and have fixed melting points, so C meets the meaning of the question.

2. (2018·Inner Mongolia Hohhot High School Entrance Examination) Put a small amount of iodine in the test tube, plug the lid tightly and put it in hot water. When the solid iodine turns into purple iodine vapor and fills the test tube, take the test tube out of the hot water and put it into cold water. The iodine vapor will turn into solid iodine and adhere to the inner wall of the test tube. Regarding the physical state change process of iodine, which of the following statements is correct ()

A. First exothermic sublimation and then endothermic condensation

B. First absorb heat and sublimate and then release heat and sublime

C. First exothermic melting and then endothermic solidification

D. First absorb heat and melt and then release heat and solidify.

The change of iodine from solid state to iodine vapor is a sublimation phenomenon, which requires the absorption of heat; when iodine vapor encounters colder glass, it will release heat and directly turn into solid iodine. This is a desublimation phenomenon, so B is correct.

3. (2018 Hubei Jingmen High School Entrance Examination) At present, the number of household cars is increasing. Which of the following hot phenomena related to cars is wrong ()

A. "Fogging" on car glass affects driving safety. This is caused by the liquefaction of water vapor in the car.

B. The "white gas" coming out of the exhaust pipe in winter is small ice crystals formed by the condensation of water vapor.

C. Adding an appropriate amount of alcohol to the car water tank lowers the freezing point of the water and prevents the water from freezing and bursting the water tank.

D. When the air conditioner is cooling, the refrigerant vaporizes, absorbs heat, liquefies and releases heat, and "moves" the "heat" inside the car to the outside of the car.

The "fog" caused by the car glass is the small water droplets formed by the liquefaction of water vapor in the car that adheres to the inner surface of the glass, so A is correct; the "white gas" coming out of the exhaust pipe in winter is the small water droplets formed by the liquefaction of water vapor when it encounters cold. So B is wrong; adding an appropriate amount of alcohol to the car water tank can lower the freezing point of water and prevent the water from freezing and bursting the water tank, so C is correct; when the air conditioner is cooling, the liquid refrigerant absorbs heat in the heat exchanger in the car and changes from liquid to gas, which occurs. After vaporization, the gaseous refrigerant is pressed into the heat exchanger outside the car by the compressor, where it releases heat and liquefies, that is, the "heat" inside the car is "moved" to the outside of the car, so D is correct.

4. (2018 Bayannur High School Entrance Examination, Inner Mongolia) In an experiment to study the boiling of water, Xiao Ming put a test tube filled with water into a beaker filled with water, as shown in Figure A.

(1) During the experiment, a large amount of "white gas" can be observed above the beaker. The name of the change in the state of matter that forms "white gas" is _________.

(2) Analyzing the image shown in Figure B, we can see that the boiling point of water is _________ ℃. When water boils, the temperature changes with time as ____________________.

(3) When the water in the beaker continues to boil for a long time, the temperature of the water in the test tube _________ (optional "greater than", "equal to" or "less than") the boiling point of the water in the beaker, the water in the test tube ________(optional) "will" or "won't") boil, which means that the conditions that must be met for liquid to boil are ____________________.

Analysis: (1) When water boils, a large amount of "white gas" appears above the beaker. This is because a large amount of water vapor is produced when water boils. The water vapor will liquefy when it is cold, forming "white gas".

(2) From the picture in the question, when the temperature of the water reaches 98 ℃, the temperature no longer changes, indicating that the water is boiling at this time, which is characterized by absorbing heat and the temperature remains unchanged. The boiling point of water is 98°C.

(3) When the water in the large beaker boils, the water in the small test tube absorbs heat from the large beaker. After the temperature reaches the boiling point of water, it is the same temperature as the water in the beaker, and it cannot continue to absorb heat from the beaker. Although the water has reached the boiling point at this time, it cannot absorb heat, so it will not boil. This means that the conditions that must be met for liquid boiling are that the temperature reaches the boiling point and continues to absorb heat.

Answer: (1)Liquefaction

(2)98 absorbs heat and the temperature remains unchanged

(3) It means that the temperature will not reach the boiling point and continue to absorb heat.

Keywords: Free download of PPT courseware for eighth grade physics volume 1 of the People's Education Press, integrated PPT download for this chapter, PPT download of changes in states of matter, .PPT format;

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Update Time: 2024-10-18

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