"Changes of Water" The most common liquid - water PPT courseware

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"Changes of Water" The most common liquid - water PPT courseware

1. Three state changes of water

Why does the water in the ocean never overflow and the water in the river never stop flowing? How does water in nature cycle and transform day and night? (water cycle)

Water in rivers, lakes, seas, and on the ground is heated by the sun and constantly evaporates, turning into water vapor and flying into the air. The water vapor is cooled in the air and turns into clouds, and the clouds turn into rain, snow, etc. and fall to the ground; the ground Some of the rainwater and melted snow water seep into the ground; the groundwater will collect and flow out of the ground to form spring water and flow into rivers, rivers, lakes, and seas. As a result, water circulates endlessly among the ocean, sky, and land.

water cycle in nature

Water has three states: solid, gas, and liquid

The three states of water can be converted into each other, the condition is the conversion of temperature

2. Electrolysis of Water

1. Experimental study on the changes of water under the action of direct current

Research objectives:

(1) Through experiments, verify the products of electrolyzed water.

(2) Through the electrolysis of water experiment, we can further understand what chemical changes are from the perspective of molecules and atoms.

(3) Cultivate the spirit of scientific inquiry.

Ask a question:

(1) What will happen if direct current is passed through the water?

(2) Are the electricity flowing through water and the three-state changes of water the same kind of change? …

Experimental steps:

(1) Fill the glass tube of the water electrolyzer with water and connect the DC power supply. Observe the changes in the liquid level in the two electrodes and the two glass tubes?

(2) Use a lit match to approach the tip of the glass tube where the liquid level has dropped more, slowly open the piston, and observe what happens.

(3) Use a wooden stick with sparks, close to the tip of the glass tube where the liquid level drops less, slowly open the piston, and observe what happens.

Schematic diagram of the decomposition of water molecules:

According to the schematic diagram of the decomposition of water molecules, please describe the information you obtained from both macro and micro aspects (3 to 4 items)

micro aspects

(1) Water is composed of water molecules;

(2) Water molecules are composed of hydrogen atoms and oxygen atoms;

(3) Oxygen molecules are composed of oxygen atoms; hydrogen molecules are composed of hydrogen atoms;

(4) In chemical changes, molecules can be divided into atoms, but atoms cannot be divided further;

(5) Atoms are the smallest particles in chemical changes.

macro aspect

(1) Water is composed of hydrogen and oxygen elements;

(2) Oxygen is composed of oxygen element;

(3) Hydrogen gas is composed of hydrogen element...

3. Hydrogen:

Hydrogen is a colorless, odorless, poorly soluble gas that produces a light blue flame when burned in the air...

Hydrogen mixed with a certain amount of air or oxygen will explode when exposed to an open flame. Therefore, the purity of hydrogen must be checked before igniting it.

combustion of hydrogen

Hydrogen can be ignited. This is a chemical reaction between hydrogen and oxygen in the air. Does the reaction produce water?

Phenomenon: Pure hydrogen burns in the air, producing a light blue flame, and water droplets condense on the wall of the beaker. If you touch the beaker with your hand and it feels hot, it means that the hydrogen gas reacted with the oxygen in the air to form water and release heat.

Literal expression for reaction:

hydrogen + oxygen → water

H2 O2 H2O

Hydrogen energy

(1) Hydrogen energy is an extremely ideal energy source with broad development prospects. It has the following advantages:

①Raw materials are not restricted (wide sources)

② Combustion releases a lot of heat (high calorific value)

③The product does not pollute the environment (no pollution) (the biggest advantage)

Why hydrogen energy is not widely used

① Flammable and explosive

②Difficult to liquefy

③ Storage and transportation are unsafe and inconvenient

④ Preparing hydrogen consumes a lot of electricity and costs a lot.

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For more information about the PPT courseware "Changes in Water: The Most Common Liquid Water", please click on the "Changes in Water ppt: The Most Common Liquid Water" ppt tag.

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Update Time: 2024-11-21

This template belongs to Chemistry courseware Beijing Curriculum Reform Edition Ninth Grade Chemistry Volume 1 industry PPT template

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