"Vaporization and Liquefaction" PPT courseware on changes in states of matter

Description

"Vaporization and Liquefaction" PPT courseware on changes in states of matter

learning target:

1. Understand the factors that affect the speed of evaporation.

2. Understand what liquefaction is and its characteristics.

3. Know how to liquefy.

1. Factors that affect the speed of liquid evaporation:

Experimental results:

Increasing the surface area of ​​a liquid speeds up evaporation

Raising the temperature of a liquid speeds up evaporation

Increasing the speed of air movement over a liquid can speed up evaporation

Summary: Factors that affect evaporation speed:

⑴The temperature of the liquid; the higher the temperature, the faster it evaporates.

⑵The surface area of ​​the liquid; the larger the surface area of ​​the liquid, the faster it evaporates.

⑶How fast the air flows on the liquid surface; the faster the surface air flows, the faster it evaporates.

2. Liquefaction:

1. What is liquefaction? What characteristics does it have?

2. What are the methods of liquefaction?

(1) Definition: The process of a substance changing from a gaseous state to a liquid state

(2) Characteristics: Liquefaction releases heat.

Such as: the formation of dew, the formation of fog.

2. Two ways of gas liquefaction

1. Lower the temperature: All gases can liquefy when the temperature drops low enough.

2. Compressed volume: Such as liquid gas tanks and liquid lighters, which use compressed volume to liquefy gas.

Liquefaction phenomena in daily life

1. In winter, the "white breath" exhaled from the mouth.

2. In summer, the "white air" around sorbet

3. The "white gas" coming out of the pot when cooking

These "white gases" are actually small water droplets, formed by the liquefaction of water vapor when it encounters cold.

Class summary

1. Factors that affect the speed of liquid evaporation:

⑴The temperature of the liquid; the higher the temperature, the faster it evaporates.

⑵The surface area of ​​the liquid; the larger the surface area of ​​the liquid, the faster it evaporates.

⑶How fast the air flows on the liquid surface; the faster the surface air flows, the faster it evaporates.

2.Liquefaction

(1) Definition: The process of a substance changing from a gaseous state to a liquid state

(2) Characteristics: Liquefaction releases heat.

3. Two ways of gas liquefaction

1. Reduce temperature 2. Compress volume

Class exercises:

1. Which of the following measures is intended to slow down evaporation? ( )

A. Blow wet hair with an electric hair dryer

B. Wrap the fruit in plastic wrap and place it in the cold storage room of the refrigerator.

C. Dry wet clothes in a sunny and ventilated place

D. Use a broom to sweep away the water spilled on the ground.

2.________ and ________ are two methods of liquefying gases.

Liquefied petroleum gas is produced using ________.

3. Refrigerators are made based on the principle that substances generate _____ heat when they vaporize and __ heat when they liquefy. When you open the refrigerator door, you see "white gas" coming out. This "white gas" is ______, which is caused by ______ being cold______.

4. People are more severely burned by 100℃ water vapor than by 100℃ boiling water. This is because ______. When the doctor examines the patient's teeth, he takes a "small mirror with a handle", burns it on an alcohol lamp, and then puts it into the patient's mouth. The purpose for the arrangement is______.

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For more information about the PPT courseware "Changes in the State of Matter, Vaporization and Liquefaction", please click on the Changes in the State of Matter ppt, Vaporization and Liquefaction ppt tab.

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Update Time: 2024-11-22

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

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