"End of Chapter Summary and Improvement" Changes in Physical State PPT

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"End of Chapter Summary and Improvement" Changes in Physical State PPT

Part One: Key Breakthroughs

Type 1 Use of Thermometer

1. A student’s method of measuring the temperature of a liquid is as shown in Figure A.

(1) Point out his mistakes in operation: the glass bulb of the thermometer touched the bottom of the container;

(2) The consequence of this error is that the measured temperature is higher (optional "high" or "low");

(3) After correcting the error, the thermometer’s reading is as shown in Figure B. The temperature of the liquid is 69°C.

Type 2 The difference between crystalline and amorphous

2. Regarding crystals and amorphous, which of the following statements is correct (B)

A. Both crystals and amorphous have fixed melting points

B. Both crystals and amorphous crystals may turn into liquids when they absorb heat

C. Both crystals and amorphous materials absorb heat when melting and the temperature remains constant.

D. Both crystals and amorphous crystals first become soft when melted, then become viscous, and finally become liquid.

Type 3 Boiling and Evaporation

3. You must have heard of "raising the soup to stop it boiling" and "drawing out the fuel from the cauldron". The correct statement about these two idioms below is (C)

A. Both "raising the soup to stop it boiling" and "drawing fuel from the bottom of the cauldron" can only temporarily stop the boiling.

B. Both can completely stop boiling

C. "Raising the soup to stop it boiling" can only temporarily stop the boiling, but "drawing the fuel from the bottom of the cauldron" can completely stop the boiling.

D. "Raising the soup to stop it boiling" can completely stop the boiling, while "drawing the fuel from the bottom of the cauldron" can only temporarily stop the boiling.

4. Pull a thermometer out of the alcohol, and its reading will be (C)

A. Keep increasing B. First increase and then decrease C. First decrease and then increase D. Keep decreasing

Type 4: Images of physical state changes

5. (Rizhao High School Entrance Examination) As shown in the picture, since a corner of the image is torn off, it is impossible to determine whether it is a melting image or a boiling image. Which of the following statements is correct (D)

A. This must be a melted image of some kind of crystal

B. This may be some kind of amorphous melted image

C. This must be an image of some kind of liquid boiling

D. Whether it is a melting image or a boiling image, heat must be absorbed within a period of time when the temperature remains unchanged.

Type 5: Three-state changes of matter and heat absorption and release characteristics

6. Physics is everywhere in life, and knowledge comes from careful observation. Regarding thermal phenomena, which of the following statements is incorrect (A)

A. The reason why the air in the cold winter of the Antarctic continent is also very humid is due to the vaporization of water, which needs to absorb heat.

B. Eating popsicles to relieve heat in summer is a melting phenomenon and requires absorbing heat.

C. The formation of fog and dew is a liquefaction phenomenon and requires the release of heat.

D. The "white air" exhaled by people in winter is a liquefaction phenomenon and requires heat release.

7. (Guangzhou High School Entrance Examination) Substance M appears in three different states of matter by absorbing and releasing heat, as shown in the figure. The states of matter A, B, and C are (C) in order

A. Solid, liquid, gas B. Gas, liquid, solid

C. Gas, solid, liquid D. Liquid, solid, gas

End-of-Chapter Summary and Improvement PPT, Part 2: Experimental Activities

Experiment 1: Explore the temperature changes when solids melt

1. Experimental equipment

Test tubes, alcohol lamps, thermometers, asbestos nets, iron stands, beakers, water, sea waves, paraffin, etc.

2. Experimental process

(1) Refer to the experimental device as shown in the figure and assemble the experimental equipment. Use the water bath method to heat the sea wave and paraffin, observe the thermometer indication and the state changes of the sea wave and paraffin, and record the results in the table.

(2) Draw points in the coordinate system according to the temperature at each moment in the table, and then connect these points with a smooth curve to obtain an image of the temperature changing with time when sea waves and paraffin melt.

3.Experimental conclusion

(1) During the melting process, sea waves are in a state of solid and liquid coexistence; sea waves continue to absorb heat when melting, but the temperature remains unchanged.

(2) Paraffin wax continuously absorbs heat during the melting process, and the temperature rises. The phenomenon changes from hard to soft, and finally becomes liquid.

[For training]

1. Xiao Ming chose beeswax and sea wave to explore "whether the temperature changes of different solid materials are the same during the melting process." The designed experimental device is shown in Figure A.

(1) Insert the thermometer correctly into the beeswax and sea wave. When observing the thermometer, keep your eyes at the ①②③ positions as shown in Figure B. The correct one is ② (optional "①", "②" or "③"), At this time, the thermometer shows 42°C;

(2) Figure C is the melting image of sea waves drawn by Xiao Ming. The BC segment in the picture represents the melting process of sea waves. During this process, sea waves absorb heat (optional "endothermic" or "exothermic"), and the temperature remains unchanged. (Select "increase", "decrease" or "no change"). At the 10th minute, the sea wave is in the state of solid-liquid coexistence (select "solid", "liquid" or "solid-liquid coexistence");

(3) As shown in Figure D, the melting image of beeswax drawn by Xiao Ming, the temperature of beeswax increases during the melting process (optional "increase", "decrease" or "unchanged");

(4) Through experiments, it can be seen that the difference between crystal and amorphous is

Crystals absorb heat during the melting process and do not heat up; amorphous materials absorb heat during the melting process and heat up at the same time.

Experiment 2: Explore the characteristics of temperature changes when water boils

1. Experimental equipment

Beaker, alcohol lamp, iron stand, asbestos net, cardboard, thermometer, water, stopwatch, etc.

2. Experimental steps

(1) As shown in the figure, install the experimental equipment in a bottom-up order.

(2) Add an appropriate amount of water to the beaker, place the beaker on the asbestos mesh, cover the beaker with cardboard with a hole in the center, put the thermometer through the cardboard hole and make the glass bulb of the thermometer completely immersed in the water.

(3) Light the alcohol lamp for heating.

(4) When the water temperature reaches 90 ℃, record the temperature every 0.5 minutes.

(5) During the experiment, observations should be made while recording, and the time and temperature should be recorded in a pre-designed form.

3.Experimental conclusion

(1) Boiling is a violent vaporization phenomenon occurring simultaneously on the surface and inside of a liquid.

(2) The bubbles in water change from large to small before boiling, and finally disappear. When boiling, they change from small to large, and finally burst at the liquid surface.

(3) The sound of water is louder before it is about to boil and quieter when it is boiling.

(4) Water must continuously absorb heat during the boiling process, but the temperature of the water remains unchanged.

End-of-Chapter Summary and Improvement PPT, Part Three: Connection between Junior High School and High School

Relative humidity is the ratio of the absolute humidity of the air to the saturated absolute humidity at the same temperature and pressure (i.e. the ratio of the mass of water vapor contained in a certain humid air to the mass of water vapor contained in saturated air at the same temperature and pressure) ). Relative humidity is measured with a thermohygrometer, the dry bulb temperature is measured, and then the difference is compared with the wet bulb temperature (i.e., the dry-humidity difference. When the temperature is constant, the greater the dry-humidity difference, the smaller the relative humidity of the air).

[For training]

Below is information about relative humidity.

① If 1 m3 of air can hold 8 g of water vapor, but actually holds 4 g, the relative humidity is 50%.

②The greater the relative humidity, the slower the water evaporates.

As shown in the figure, the bubble of one thermometer is covered with water-soaked cloth (wet bulb thermometer), and the bubble of the other thermometer is directly exposed to the air (dry bulb thermometer). Using the readings of the two thermometers and the following table, we can get relative humidity at that time.

(1) When the dry bulb thermometer indicates 16°C, the wet bulb thermometer indicates 14°C (as shown in the figure). It is deduced from the table that the relative humidity at this time is 80%;

(2) Summarize "the relationship between relative humidity and the temperature measured by the dry bulb thermometer when the difference between the readings of the wet bulb thermometer and the dry bulb thermometer is 3°C" based on the table data:

When the difference between the readings of the wet bulb thermometer and the dry bulb thermometer is 3°C, the higher the temperature measured by the dry bulb thermometer, the greater the relative humidity;

(3) Briefly explain why wet clothes are difficult to dry on days when the relative humidity in Guangzhou is greater than 90%: the greater the relative humidity, the slower the water evaporates. On days when the relative humidity in Guangzhou is greater than 90%, liquid water evaporates very slowly and wet clothes Very difficult to dry.

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Update Time: 2024-09-11

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