"The Composition of Water" PPT courseware

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"The Composition of Water" PPT courseware

Part One: Want to discuss

Use the knowledge you have learned and combine it with life reality to summarize the important physical properties of water.

Thinking: Water changes during its circulation in nature. Is it a physical change or a chemical change?

Have you ever seen chemical changes in water in your life? Is there any way you can chemically change water?

Does water conduct electricity?

Pure water is almost non-conductive. Water in daily life contains many impurities and is not pure water, so water in daily life will conduct electricity.

The composition of water PPT, part 2 content: careful observation

Observe carefully: the color and state of the water are ________, ________ appears on the two electrodes, the liquid levels in the two glass tubes are ________, and the volume ratio of the gas produced is approximately ________.

Hold a lit match close to the tip of the glass tube where the liquid level has dropped significantly, slowly open the piston, and observe ________;

Use a wooden stick with sparks to approach the tip of the glass tube where the liquid level drops less, slowly open the piston, and observe ________.

Take a look and think about it

From a molecular perspective, what is the difference between the evaporation of water and the decomposition of water?

When water turns into water vapor, the water molecules themselves do not change, but the distance between the molecules becomes larger.

During water electrolysis, water molecules are broken down into hydrogen atoms and oxygen atoms, and the water molecules are destroyed.

The composition of water PPT, the third part of the content: practicing writing

1. Electrolysis of water generates hydrogen and oxygen. Explain ( )

A. Water is composed of hydrogen and oxygen

B. Water is a mixture of hydrogen and oxygen molecules

C. Water is composed of hydrogen and oxygen elements

D. Any substance can decompose when electricity is applied

2. Decide whether the following statements are correct:

(1) Hydrogen and oxygen can be obtained by electrolysis of water, so water contains hydrogen and oxygen. ( )

(2) Water can evaporate into hydrogen and oxygen. ( )

(3) Water molecules are destroyed during water electrolysis. ( )

3. Answer the following questions based on the picture on the right:

①. A small amount of sodium hydroxide or sulfuric acid is often added to electrolyzed water for the purpose of ______________.

②. According to the figure: A is the ____ pole of the power supply, and B is the ____ pole of the power supply.

③. According to the picture, it can be seen that the gas collected in test tube A is _____, and the gas collected in test tube B is ______. It can be tested with ________.

④. According to the above experimental facts, it can be concluded that water is composed of ________.

4. There are two bottles of colorless gases in the laboratory. One is air and the other is oxygen. Can you identify them? Please tell me your method.

Method 1: Put the wooden stick with sparks into the bottle. The oxygen that makes the wooden stick re-ignite is the air that makes no obvious change.

Method 2: Put the burning wood stick into the bottle. The oxygen that makes the wood stick burn more vigorously, and the air that makes no obvious change.

Keywords: Zhejiang Education Edition eighth grade science PPT courseware free download, composition of water PPT download, .PPT format;

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Update Time: 2024-11-18

This template belongs to science courseware Zhejiang Education Edition Eighth Grade Science Volume 1 industry PPT template

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