"Sublimation and Sublimation" PPT Courseware on Changes in State of Matter 4

Description

"Sublimation and Sublimation" PPT Courseware on Changes in State of Matter 4

learning target

1. Understand the concepts of sublimation and sublimation

2. Know that sublimation absorbs heat and sublimation releases heat.

3. Remember that the common phenomenon of sublimation and condensation in life can explain some related phenomena.

Think about it:

Did you notice anything when you saw this light bulb?

1. Why does the light bulb turn black?

2. How is black material formed? …

sublimation

The phenomenon of matter changing from solid state directly to gaseous state is called sublimation

Solid ice turns directly into gaseous water vapor, which is the sublimation of ice

How does the white fog on the stage form?

Dry ice (solid carbon dioxide) is sprayed onto the stage, rapidly sublimating and cooling, causing the water vapor in the air to liquefy into small water droplets when cooled.

Sublime

The phenomenon of matter changing directly from gaseous state to solid state is called sublimation

Standard training

Discuss the changes in the state of matter in each of the following phenomena and explain the absorption and release of heat.

1. Iodine turns into purple gas (sublimation and heat absorption)

2. The sanitary ball has become smaller (sublimation and heat absorption)

3. Formation of frost (condensation and heat release)

4. Formation of fog and dew (heat generated by liquefaction)

5. Water freezes (freezing releases heat)

6. Clothes are dried in the sun in summer (vaporization and heat absorption)

think

Clouds, rain, snow, dew, fog, and frost are very common natural phenomena. Do you know how they are formed?

Clouds: The temperature is higher during the day, and surface water evaporates a lot, so the air contains a lot of water vapor. At this time, after the water vapor rises to the cold high altitude, it liquefies into small water droplets. A large number of small water droplets are suspended in the high altitude to form clouds. (liquefaction)

Rain: Small water droplets in clouds gather together to form large water droplets that fall down and become rain (liquefy)

Fog: If there is a lot of floating dust in the air, the water vapor will liquefy into small water droplets when cooled and attach to the floating dust, and float in the air together with the floating dust. This is fog. (liquefaction)

Dew: When the weather is hot, the water vapor in the air encounters the cooler leaves, flowers, plants, etc. before morning, and liquefies into small water droplets attached to their surfaces. This is dew. (liquefaction)

Consolidation exercises

1. Among the following descriptions about the formation of clouds, dew, fog, and frost, which one is correct ( )

A. Clouds are formed when water vapor rises to high altitudes, the temperature drops and condenses into small water droplets and sublimates into small ice crystals.

B. Fog is formed by the liquefaction of air floating on floating dust.

C. Dew is small ice crystals in clouds that melt into small water droplets

D. Frost is when water vapor in the air first liquefies into small water droplets and then solidifies into small ice crystals

2. Connect the following phenomena with the corresponding physical state changes with lines

The ice cream has melted.

The watered ground has dried and solidified

The more mothballs are placed, the smaller they become and they vaporize

Frost forms on tree branches and liquefies

Casting workpieces with molten iron for sublimation

"White gas" is generated above the steamer and condenses

Questions to think about?

11. In summer, Xiao Ming went to buy a popsicle to quench his thirst. The salesperson took out the popsicles from the freezer, and Xiao Ming found that the hard popsicles were stained with white "powder"; as soon as the wrapping paper was peeled off, "smoke" came out of the popsicles;

He put the popsicle into the teacup. After a while, the popsicle turned into a glass of water, and the outer wall of the teacup was "sweating". Can you help explain these phenomena?

[Analysis]

This question is answered based on the knowledge about changes in the state of matter. A hard popsicle has just been taken out of the freezer. The white "pink" that Xiao Ming sees is frost. It is produced by the condensation of water vapor in the freezer on the popsicle.

Once the paper is peeled off, the popsicle will emit "smoke". The smoke here is essentially a mist composed of a large number of small water droplets. It is formed by the water vapor in the air around the popsicle that liquefies when it cools;

Put the popsicle in the tea cup, and after a while, the popsicle turns into a glass of water. Made from melted ice

The outer wall of the tea cup will "sweat", which is essentially a large number of small water droplets. It is formed by the liquefaction of the water vapor around the cup when it encounters the tea cup that has been cooled by the popsicle.

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For more information about the PPT courseware "Sublimation and Sublimation Changes in the State of Matter", please click the Sublimation and Sublimation ppt Changes in the State of Matter ppt tag.

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Update Time: 2024-10-29

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

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