"Exploring the Characteristics of Vaporization and Liquefaction" Material Forms and Their Changes PPT Courseware

Description

"Exploring the Characteristics of Vaporization and Liquefaction" Material Forms and Their Changes PPT Courseware

teaching objectives

1. Describe the basic characteristics of the three states of matter: solid, liquid, and gas. List the different states of matter in nature and life and their applications.

2. Know what vaporization and liquefaction are, and know that vaporization absorbs heat and liquefaction releases heat.

3. Know what evaporation is and the factors that affect the speed of evaporation. Know the phenomenon of boiling and the characteristics of boiling, and know what the boiling point is.

4. Be able to use the knowledge of vaporization and liquefaction to explain relevant phenomena in nature and life.

5. Experience the experimental exploration process of water boiling, observe the phenomenon when water boils, learn to use image methods to represent experimental data, and discover the characteristics of temperature changes when water boils.

6. Cultivate students’ good observation habits.

1. Vaporization and its characteristics:

1. Definition of vaporization:

In physics, the phenomenon of a substance changing from a liquid state to a gaseous state is called vaporization.

2. A way of vaporization: evaporation

①Evaporation - a slow vaporization phenomenon that only occurs on the surface of a liquid.

Activity 1: What factors are related to the evaporation speed of liquid?

Does the same piece of clothing dry equally quickly under different conditions? What does this mean? What are the factors that affect the speed of evaporation?

Tip: What research methods to use when considering research?

Control Variable

②Factors that affect evaporation speed:

To speed up the evaporation of liquids you can:

A. Increase the temperature of the liquid

B. Increase the surface area of ​​the liquid

C. Accelerate the flow of air above the liquid surface

To slow the evaporation of a liquid, do the opposite

Training 1: Wet clothes will dry out after a period of time. This is actually the ______ process of water. It is a ______ phenomenon in the change of physical state. It can be carried out at ______ temperature.

Training 2: A cup of alcohol at 40℃. Open the lid and the alcohol will continue to evaporate. The remaining alcohol temperature is ______40℃ (fill in: higher, lower or equal to).

Training 3: Fans make you feel cool in summer. This is because ( )

A. The wind blowing from the fan is cool

B. The wind blew away the heat from the body

C. The wind blown by the fan can speed up the evaporation of sweat and thus speed up the absorption of heat from the human body.

D. Fans can lower the air temperature

Training 4: When swimming in summer, you don’t feel cold in the water, but you feel cold when you land on the beach. This is because ( )

A. The temperature of water is high and the temperature of air is low

B. Air conducts heat more easily than water

C. The evaporation of water on the surface of the human body requires heat to be absorbed

D. None of the above are correct

think about it

(1) Can I use an alcohol thermometer to measure the temperature of boiling water?

(2) Can a pot made of paper be used to boil water on the fire? Why can I use a paper pot to boil water?

(3) Both the large beaker and the small beaker contain water. Place them as shown in the figure. Heat the large beaker. Who boils the water first?

Understanding the liquid boiling process

Figure A is a diagram of the device used to complete the water boiling experiment, and Figure B is the thermometer indication when boiling, then:

1) What is the boiling point of water?

2) When installing the experimental device, which iron ring in AB should be fixed first?

3) What is the reason for the too long heating time in the experiment?

4) What do the bubbles look like when boiling?

2. Liquefaction and its characteristics:

1. Definition of liquefaction:

In physics, the phenomenon of changing a substance from a gaseous state to a liquid state is called liquefaction.

Can you explain the following common liquefaction phenomena in life?

The method in which we put hot water vapor into a cold environment to liquefy it is called the cooling method. So is there any other way to liquefy the gas?

Think about it: How does the liquefied petroleum gas used at home turn the liquefied petroleum gas into liquid and put it in a cylinder?

The gas is liquefied by compressing the gas. This method of liquefying the gas is called pressurization.

This method makes the storage and transportation of gas more convenient.

2. Method of liquefying gas:

① Cooling; ② Pressurization.

3. Characteristics of liquefaction:

① Heat will be released when gas liquefies;

② When liquefied, it can increase the temperature of the surrounding environment;

think about it

1. Breathe into your hands with your mouth. How do your hands feel after a few seconds? What about blowing?

2. Being burned by steam is more serious than being burned by boiling water. Do you know the reason now?

Gas releases heat when it liquefies. When boiling water or cooking, people who are burned by 100°C water vapor often suffer serious injuries, not only because of the high temperature of the water vapor, but also because of the heat released when the water vapor liquefies.

Operation:

Classwork: Questions 1, 2, 3, 4, and 5 on page p93.

Tutorial (preview): a. What are melting and solidification? Know that melting absorbs heat and solidification releases heat. Give examples of solidification and melting phenomena in life.

b. Exchange the characteristics of crystalline and amorphous melting and solidification. What are melting point and freezing point? Will check the melting point table.

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"Exploring the Characteristics of Vaporization and Liquefaction" Material Forms and Their Changes PPT Courseware 2:

"Exploring the Characteristics of Vaporization and Liquefaction" Material Forms and Changes PPT Courseware 2 Learning Objectives 1. Be able to distinguish between solid, liquid and gaseous states of matter. Know what vaporization and liquefaction are. Know that vaporization absorbs heat and liquefaction releases heat. 2. Know what evaporation is and how it affects evaporation speed..

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Update Time: 2024-10-19

This template belongs to Physics courseware Guangdong and Shanghai version of eighth grade physics volume one industry PPT template

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