"Melting and Solidification" PPT Courseware on Changes in State of Matter 10

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"Melting and Solidification" PPT Courseware on Changes in State of Matter 10

Changes in physical state

How are these natural phenomena formed?

Snow, rime, tree hanging, ice, dew, fog, rain, white clouds

They are actually all water, different states of water.

As temperature changes, substances (such as water) will change between solid, liquid, and gas states. This phenomenon is called change of state of matter.

The change of substance from solid to liquid is called melting

The change of substance from liquid to solid is called solidification

2. Explore the rules of temperature changes during solid melting

(1) Experimental device:

(2) Precautions during the experiment: Safety in the use of alcohol lamps

(3) Hypo and paraffin melting data table

Analysis and argumentation

Hypo melting has a definite melting temperature

During the melting process, the endothermic temperature remains unchanged

There is no definite melting temperature when wax melts

During the melting process, the endothermic temperature continues to rise

(4) Melting curve analysis of sea wave and wax:

① What is the state of the sea wave during the period of time corresponding to the AB segment curve? How does the temperature change?

② At which point on the curve does the sea wave begin to melt?

③ What is the state of the sea wave during the period corresponding to segment BC? Does the temperature change? Was the sea wave heated during this time?

④ What is the state of the sea wave in the time period corresponding to the CD segment? How does the temperature change?

⑤ How does the temperature of the wax change during the entire process?

(5 Conclusion:

1. Hypo has a certain melting temperature; (up to 48°C) the melting process absorbs heat and keeps the temperature constant.

2. Paraffin wax does not have a certain melting temperature. The melting process absorbs heat and the temperature rises.

4. Solidification

Analyze the solidification curve of sea waves

(1) The DE segment indicates that the sea wave is in _____ state, _____ heat (optional "suck" or "release"), and temperature ________.

(2) The EF segment indicates that the physical state of sea waves is __________, _____ heat, and temperature ________.

(3) The FG segment indicates that the state of the sea wave is ______, _____ hot, and the temperature ________.

Group discussion: What conditions are needed to completely melt an ice cube into water?

1. Let the temperature of the ice cube reach 0℃

2. Ice cubes continue to absorb heat

Crystal melting conditions: reaching the melting point and absorbing heat

Crystal melt solidification conditions: reaching the freezing point and releasing heat

Melting endothermic Solidification exothermic

From the analysis of the experiment just now, it can be seen that the sea wave and wax must be heated with an alcohol lamp during the melting process.

This shows that the solid absorbs heat during the melting process

It takes a period of time for the molten sea wave and wax to solidify.

This shows that the liquid releases heat during the solidification process

Think about the meaning

Do you know any examples in life where melting absorbs heat or solidification releases heat?

Practice in class

1. The basis for dividing solids into crystalline and amorphous is ________.

2. Judgment: Various solids have certain melting points ( )

3. During the science review class, the teacher wrote a couplet. The first couplet is "Ice water in the cup, the temperature of the water does not drop when it freezes"; the second couplet is "There is ice in the dish, but the temperature of the ice does not rise". The material changes contained in the couplet are ________, and the reflection of a commonality is ________.

4. As shown in the figure, the temperature changes with time when the two substances are in the solid state. Please answer the following questions based on the image.

(1) Judgment from the graph that the line on the _______ graph is a crystal, the melting point of the crystal is _______, the melting time is minutes, and the substance on the other graph line may be _______.

(2) The temperature rises in the _______ section, and the temperature remains unchanged in the _______ section.

Segment AB is in _______ state, segment BC is in _______ state,

The CD segment is in the _______ state, and the heat-absorbing segment is the ______________ segment.

5. Some people say that melting snow is sometimes colder than snow. Is this true?

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

"Melting and Solidification" PPT courseware:

Contents of the first part of the PPT courseware "Melt and Solidify": Three states of matter: Take water as an example: ice rain, white gas, fog, dew, frost, snow, hail Water vapor Solid state: ice, frost, snow and hail Liquid state: rain, fog, dew, white gas Gaseous state: water Vapor (invisible to the human eye) ... ...

"Melting and Solidification" PPT:

"Melt and Solidification" PPT Part 1 Content: State Changes Solid, liquid, and gaseous states are the three common states of matter. Solid state: such as aluminum, gold, silver, copper, iron, etc. are usually solid. Liquid state: such as water, vinegar, oil, etc. are usually liquid. Gaseous state: such as oxygen, hydrogen,...

"Exploring the Characteristics of Melting and Solidification" Material Forms and Their Changes PPT Courseware 2:

"Exploring the Characteristics of Melting and Solidification" Material Form and Its Changes PPT Courseware 2 Learning Objectives 1. Know what melting and solidification are. Understand the endotherms of melting and the exotherms of solidification. Know the characteristics of crystalline and amorphous melting and solidification. Understand the physical meaning of melting curves. 2. know..

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Update Time: 2024-09-09

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