"Air" The air around us PPT courseware 5

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"Air" The air around us PPT courseware 5

Think about it 1: Since air is so important, can you use a simple experiment or give an example to show that air does exist?

Answer: 1) An empty gas bottle is pressed down in a tank filled with water - the water in the gas bottle cannot rise to the top.

2) Shake the flat, dense bag after opening it, and then seal it - squeeze it with both hands to feel pressure.

3) The fan is blowing towards the face, the leaves are moving - there is wind

4) Pump up the tire - make it rise

1. What is air made of?

In order to understand the composition of air, many scientists have devoted themselves to research in this area, such as Swedish chemist Scheele and British chemist Priestley. The most famous of them is the experiment done by French chemist Lavoisier.

Idea:

①Mercury (silver white, liquid) + air heat the red powder (the air in the closed container is reduced by 1/5V) + remaining gas 4/5V (volume of nitrogen).

②Red powder heated air analysis of mercury +1/5V concluded that air is composed of oxygen and nitrogen, of which oxygen accounts for about 1/5V of the total volume of air

Experimental steps

Check the air tightness of the device;

Put a small amount of water into the gas collecting bottle, then divide the remaining volume into five equal parts and mark them;

Light the red phosphorus, immediately reach into the bottle and tighten the stopper;

Wait for the red phosphorus to stop burning and the temperature to drop, then open the spring clip.

What phenomena did you see during the experiment?

Phenomenon:

1. Red phosphorus burns, releases heat, emits yellow-white flame, and produces thick white smoke (small solid particles).

2. The water level in the container rises by about 1/5.

Why does water enter the gas collecting bottle?

Explanation of experimental principles:

After a sufficient amount of red phosphorus is burned, the oxygen in the gas collecting bottle is exhausted and solid phosphorus pentoxide is generated. After the burning stops and the temperature decreases, the pressure inside the bottle decreases. When the spring clamp is opened, the water in the beaker acts on the atmosphere. down, flowing into the gas collecting bottle, increasing the volume of oxygen in the air

Activity world

1. By volume, the most abundant gas in the air is _____, and its approximate percentage of air volume is _____; the second most abundant gas is _____, and its approximate percentage of air volume is _____.

2. Among the following substances, which one is pure?

A. Distilled water b. Sprite drink

C. River water D. fresh air

3. The picture below is an experimental device for measuring the oxygen content in the air. Please answer the questions based on the experiment:

(1) What are the main observable experimental phenomena? Write a literal expression of the reaction.

(2) After combustion, the remaining gas in the bell jar is mainly nitrogen. Based on this experiment, please speculate whether nitrogen can support combustion? Why?

3. Protect the air

What are the sources of man-made pollution? Do you know what substances pollute the air?

1) Industrial pollution.

2) Living pollution.

3) Traffic pollution.

4) Agricultural pollution.

Carbon monoxide, sulfur dioxide

Hydrogen sulfide, nitrogen dioxide

1. Main pollutants: sulfur dioxide, carbon oxides, nitrogen oxides, hydrocarbons, flying dust, coal dust, radioactive substances, etc.

air pollution sources

Nature: volcanic eruptions, earthquakes, forest fires

2. Three major environmental issues

(1) Acid rain: sulfur dioxide (SO2)

(2) Greenhouse effect: carbon dioxide (CO2)

(3) Ozone hole: chlorofluorocarbons

Governance:

1. Reduce the use of fossil fuels such as coal, oil, and natural gas (or perform de-S treatment during combustion)

2. Improve the fuel structure and install purification devices to reduce harmful gas emissions.

3. Reduce industrial waste gas emissions, recycle, purify and reuse waste gas.

4. Vigorously plant trees and strictly prohibit indiscriminate logging

5. Develop new energy (solar energy, hydrogen energy, wind energy, geothermal energy, etc.)

6. Government departments should make reasonable plans, set standards, and strengthen monitoring.

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Update Time: 2024-10-03

This template belongs to Chemistry courseware People's Education Press Ninth Grade Chemistry Volume 1 industry PPT template

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