"Melting and Solidification" Temperature and Physical State Changes PPT Courseware

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"Melting and Solidification" Temperature and Physical State Changes PPT Courseware

Thinking: How does the state of matter change in the picture below?

Magma freshly erupted from the volcano cools into volcanic rock

Physics middle class

The process of a substance changing from solid to liquid is called melting.

The process of matter changing from liquid to solid is called solidification

Name the following changes in states of matter

1. Popsicles turn into water: melt

2. Molten steel is cast into train wheels: solidification

3. Recycle waste plastic into plastic products: melt first and then solidify

Think: What conditions are needed for substances to melt and solidify?

Are the laws of melting and solidification of different substances the same?

Activity 1: Explore the melting characteristics of ice and candle wax

[Ask a question]: At what temperature do ice and candle wax begin to melt? How does the temperature change during the melting process?

[Conjectures and Assumptions]:

1. Ice and candle wax have (with/without) a certain temperature when melting

2. How do the temperatures of ice and candle wax change when they melt (increase/decrease/no change)

[Experimental steps]:

1. Insert a thermometer into the ice cube and record the reading of the thermometer.

2. After heating with an alcohol lamp, record the temperature every 0.5 minutes. At the same time, pay attention to the changes in the state of the ice in the cup until 5 minutes after all the ice melts.

3. Heat the candle, record the temperature indication every 0.5 minutes, and observe the state changes of the candle until 5 minutes after the candle is completely melted.

think about it

1. What are the characteristics of temperature changes during the melting process of the above two substances?

2. During the period of time corresponding to the AB segment curve, what are the states of ice and candles? How does the temperature change?

3. In segment BC, what are the states of ice and candles? Does the temperature change?

4. In the CD segment, what are the states of ice and candles? How does the temperature change?

Summarize the melting laws of candles and ice:

1. When the temperature is lower than 0 ℃, the ice will melt when the ice is heated. When the temperature reaches 0 ℃, the ice will be _______ when the ice is heated. The temperature of ice during melting is _______.

After the candle is heated, it is found that the candle _______ melts, and the temperature __________ during the melting process.

2. Solids require _______ heat when melting

Solid classification

According to the rules shown when solids melt, solids are divided into:

Crystal: Objects have a fixed melting temperature when melted. Such objects are called crystals.

Amorphous: Objects have no fixed melting temperature when melting. Such objects are called amorphous.

Discussion: What is the difference between crystals and amorphous?

Crystal: During the melting process, it continuously absorbs heat, but the temperature remains unchanged.

Amorphous: During the melting process, it continuously absorbs heat and the temperature continues to rise.

Note: The temperature at which a crystal melts is called the melting point; amorphous crystals have no definite melting point.

What conditions are required for crystal melting?

1. The temperature must reach the melting point

2. Continue to absorb heat

Note: Two conditions cannot be missing.

practise:

1. Can aluminum be melted in a tin pot?

2. Check the table to determine the states of the following substances at the following temperatures?

Ocean waves at 47ºC _______. Mercury at -38ºC_______.

-15ºC water ________. Pure iron at 1536ºC_______.

Ocean waves at 48ºC____________________.

Practice in class

1. To heat the ice-water mixture, then ( )

A. The temperature of ice increases, but the temperature of water remains unchanged.

B. The temperature of the ice remains unchanged and the temperature of the water increases.

C. The temperature of the ice water increases together

D. When ice melts into water, the temperatures of both ice and water remain unchanged.

2. 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 _______, and the melting time is _______ minutes. 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 _________

3. Haibo’s confession:

"My name is Hai Bo. My melting point and freezing point are both 48°C. Now my body temperature is exactly 48°C. Please tell me, should I melt or solidify? As long as you are right, I will do as you say. Do it."

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

"Melting and Solidification" Temperature and Physical State Changes PPT Courseware 3:

"Melting and Solidification" Temperature and Physical State Changes PPT Courseware 3 Project Main Contents Melting and Solidification The process of melting substances from ______ to ______ The process of solidifying substances from ______ to ______ Crystalline and non-crystalline solids Classified crystals have fixed _____..

"Melting and Solidification" Temperature and Physical State Changes PPT Courseware 2:

"Melt and Solidification" Temperature and Physical State Changes PPT Courseware 2 1. Three states and changes of matter 1. There are three states of matter: solid, liquid, and gas. 2. The change of matter from one state to another is called change of state of matter 3. Melting and solidification 2. Explore solid melting..

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Update Time: 2024-07-31

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