"Vaporization and Liquefaction" PPT Courseware on Changes in State of Matter 8

Description

"Vaporization and Liquefaction" PPT Courseware on Changes in State of Matter 8

learning target

1. Know what vaporization and liquefaction are.

2. Understand the phenomenon of boiling and know what the boiling point is. Understand the characteristics of liquids when they boil.

3. Know that evaporation can cause cooling. Learn the difference between evaporation and boiling.

4. Understand that liquefaction is the reverse process of vaporization. Learn about the two methods of liquefaction. �

Self-study guide one

The self-study textbook contains pages 58-60. After 4 minutes, answer the following questions:

1. What is vaporization? What is liquefaction? for example.

2. What is boiling? What is boiling point? Does vaporization require heat release or heat absorption?

Boiling: Violent vaporization occurring simultaneously inside and on the surface of a liquid at a certain temperature.

Ask a question

What are the characteristics of water when it boils? If you continue to heat water after it boils, will the temperature get higher and higher?

Purpose of the experiment: To observe the phenomenon of water boiling and the temperature of water when it boils.

Experimental steps:

1. Install the experimental instruments according to the installation diagram.

2. Use an alcohol lamp to heat the water and observe.

3. When the water temperature approaches 90°C, record the temperature every 1 minute and observe the boiling phenomenon of the water.

4. Complete the curve of the relationship between temperature and time when water boils.

Observation phenomenon:

1. What happens when bubbles rise before and during boiling?

2. During the heating process of water before boiling, the temperature continues to rise. During the boiling process of water, although it continues to be heated, it maintains a certain temperature.

3. There is more and more "white gas" on the liquid surface. When the water boils, violent vaporization occurs in the water, forming a large number of bubbles, which rise and grow until the water surface bursts, and the water vapor inside is emitted into the air.

4. After boiling, remove the alcohol lamp and the water will stop boiling.

Experimental results:

1. Boiling is a _________ phenomenon that occurs when a liquid _________ at the same time.

2. The temperature of water is ______ when it boils. When liquid boils, it has a certain temperature. This temperature is called ______. At 1 standard atmosphere, the boiling point of water is ______℃.

3. The conditions for boiling are:

(1) The temperature reaches the boiling point

(2) Continue to absorb heat

Self-study guide 2

Self-study textbook, pages 60-61, answer the following questions after 4 minutes:

1. What is evaporation? What does evaporation do?

A slow vaporization phenomenon that occurs only at the surface of a liquid at any temperature.

Evaporation absorbs heat and has the effect of cooling and cooling.

2. How many methods are there to speed up evaporation?

(1) Increase the temperature of the liquid.

(2) Increase the surface area of ​​the liquid.

(3) Speed ​​up the air flow on the liquid surface.

3. What are the similarities and differences between boiling and evaporation?

Factors that affect the speed of liquid evaporation:

(1) The temperature of the liquid.

(2) The size of the liquid surface area.

(3) How fast the air flows on the liquid surface.

On-the-job training:

1. Fill in the blanks:

1. The phenomenon of matter changing from ( ) state to ( ) state is called vaporization; the phenomenon of matter changing from ( ) state to ( ) state is called liquefaction. Evaporation and ( ) are two ways of vaporization.

2. The conditions for liquid boiling are: ( ) and ( ).

3. When swimming in a swimming pool in summer, you will shiver with cold when you first come out of the water. This is because ( ).

4. When a patient has a high fever, you may use alcohol to rub the patient's body, which can lower the temperature. The reason is that alcohol ( ) comes from the human body ( ), so the patient's body temperature decreases.

2. Choice:

1. If you continue to heat the water in the kettle after it boils, the temperature of the water in the kettle will be ( )

A. Continue to rise B. constant

C. Slowly decrease D. high and low

2． Sprinkling some water in the classroom in summer will make you feel cooler. The main reason is ( )

A. Cold water has low temperature

B. Water spilled on the ground absorbs heat when it evaporates, lowering the air temperature.

C. There is less water vapor in the air

D． It’s human psychology

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Update Time: 2024-11-24

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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