"Exploring Combustion and Fire Extinguishing" PPT courseware on combustion knowledge

Description

"Exploring Combustion and Fire Extinguishing" PPT courseware on combustion knowledge

Combustion: a violent chemical reaction that emits light and heat

Note:

1 Combustion is an exothermic reaction

2 chemical reactions

Exothermic reaction

endothermic reaction

Exothermic reaction: a chemical reaction that releases heat during the reaction. All combustion is an exothermic reaction.

Application: Chemical reactions in the human body release heat to maintain body temperature, burning for heating, cooking food, refining metal, etc.

Endothermic reaction: Chemical reactions that require heat absorption during the reaction process, such as heating potassium permanganate to produce oxygen, decomposition of basic copper carbonate, etc. are all endothermic reactions.

Combustion is a luminous and heat-generating oxidation reaction between combustibles and oxygen.

Notice:

1. Combustion is a chemical change

2. Changes in luminescence and heating phenomena are not necessarily combustion, such as the luminescence and heating of electric lamps.

3. Combustion generally refers to the oxidation reaction between combustibles and oxygen, but it is not absolute. Sodium burns in chlorine

Slow oxidation and spontaneous combustion

Some oxidation reactions proceed so slowly that they are not even easily detected. This slowly progressing oxidation is called slow oxidation (respiration of animals and plants, decay of food, brewing of wine and vinegar, rust of steel, decomposition of farmyard manure)

Spontaneous combustion caused by slow oxidation is called autoignition. Therefore, combustion does not require ignition or heating

1. Combustion conditions

Experiment 1: Use matches to light wood and stones respectively

Experiment 2: Light a small candle and cover it with a beaker

Experiment 3: Light a piece of paper and a piece of wood with a match. Compare the difficulty of igniting them.

Material combustion needs to meet three conditions at the same time:

1. The substance must be flammable

2. Combustible materials must be in contact with air or oxygen

3. To reach the ignition point of flammable materials

Broaden your horizons: Why does a burning candle go out as soon as you blow it out, but a coal fire becomes brighter when you fan it?

analyze:

A candle burns and releases less heat. Blowing it with your mouth will cause the heat generated to be lost with the flow of air, and the temperature will drop below the ignition point, so the candle will go out.

There is a lot of fuel in the coal stove, and a lot of heat is released when the fuel burns. The fan will not reduce the temperature of the coal stove below the ignition point, and the fan will circulate the air and supplement the oxygen, so the fan will become more prosperous.

Class exercises

1. Which of the following statements about combustion is correct ( )

A Combustion is a physical change that must involve oxygen or air

B Combustion is a violent chemical reaction that produces light and heat.

C changes that produce light and heat must be combustion

DEvery burning substance must produce a flame

2. Substance combustion must

Conditions: (1) The substance must have _______; (2) The combustible substance must have _______; (3) The combustible substance must reach the _______ required for combustion. This temperature is called the _______ of the combustible substance.

3. Xiaohong added an appropriate amount of water to the paper boat and heated it directly with an alcohol lamp. The paper boat was safe and sound. The main reason why the paper boat did not burn is ( )

A paper is not flammable

B is not in contact with oxygen

C has not reached the ignition point

D. Water can reduce the ignition point of paper boats and thus extinguish fires.

4. In an experiment to explore combustion conditions, Xiao Ming found that cotton is more easily ignited than coal. He thinks this is mainly because ()

A. Cotton has a larger contact area with air than coal

B. Cotton has a higher ignition point than coal

C. Cotton has a lower ignition point than coal

D.Cotton is denser than coal

Analysis of factors affecting the combustion phenomenon of combustibles:

1. Why do carbon, sulfur and phosphorus burn differently in the air?

Because the properties of substances are different, the combustion conditions will also be different.

2. Why do wood shavings and small pieces of wood burn better than large pieces of wood? The same wood has the same ignition point, so what’s the reason?

Because thin and small combustibles have a large contact area with oxygen, they burn more vigorously.

3. Why does sulfur burn in the air and emit a weak light blue flame, but burn in oxygen and emit a bright blue-purple flame?

Because the phenomenon of substance burning is related to the concentration of oxygen.

3. Safety knowledge of flammable and explosive materials

Explosion principle:

Combustible materials burn rapidly in a limited space, accumulating a large amount of heat in a short period of time, causing the volume of the gas to expand rapidly and causing an explosion.

For example, the setting off of firecrackers, the explosion of bombs, etc. . .

Type of explosion:

1. Combustible materials burn rapidly in a limited space, accumulating a large amount of heat in a short period of time, causing the volume of the gas to expand rapidly and causing an explosion.

2. The contact surface between combustibles (such as gas and dust) and oxygen is very large, and a large amount of heat is quickly released. The surrounding air expands rapidly and violently, and may also explode.

Note: Any flammable gas or combustible dust may explode when exposed to an open flame after being fully mixed with air. Therefore, fires should be eliminated in corresponding places.

Attention when producing, transporting, using and storing flammable and explosive materials:

1. Strictly abide by relevant regulations and never operate in violation of regulations.

2. A sound fire protection system must be established, equipped with complete fire protection facilities and ventilation equipment, and fireworks must be strictly prohibited;

3. The warehouse should be dry and cool, and fire and explosion-proof inspections should be carried out frequently.

4. Handle with care when transporting to avoid collisions and prevent accidents.

Use your knowledge of chemistry to briefly analyze the following phenomena.

⑴ Warehouse managers handling flammable and explosive materials are strictly prohibited from wearing chemical fiber clothing.

⑵ On a summer afternoon, a haystack suddenly caught fire, but there was no trace at the scene.

⑶ Combustibles burn more vigorously in oxygen than in air.

(4) White phosphorus is stored in water

Explosion limits of flammable gases and dusts (lower limit):

Refers to the mixture of flammable gas (or dust) and air, the concentration range of flammable gas (or dust) that can explode in case of fire

Note:

1The explosion limit of flammable gas is expressed by its volume fraction in air

2. The lower explosion limit of flammable dust is expressed by the mass of dust in a certain volume of air.

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For more information about the PPT courseware "The Knowledge of Combustion Exploring Combustion and Fire Extinguishing", please click the "The Knowledge of Combustion ppt Exploring Combustion and Fire Extinguishing" ppt tag.

"Exploring Combustion and Fire Extinguishing" PPT Courseware on Combustion 3:

"Exploring Combustion and Fire Extinguishing" Combustion Knowledge PPT Courseware 3 Learning Objectives 1. Knowledge and Skills: Use chemical science knowledge to explain some phenomena and causes of combustion and fire extinguishing in daily life. 2. Processes and Methods: Through understanding of combustion conditions and fire extinguishing Exploration activities on principles, etc..

"Exploring Combustion and Fire Extinguishing" PPT Courseware on Combustion 2:

"Exploring Combustion and Fire Extinguishing" PPT Courseware on Combustion 2 Preview 1. The definition of combustion. 2. Three conditions required for combustion. 3. Principles and methods of fire extinguishing. 1. Combustion definition: A violent oxidation reaction that produces light and heat between combustibles and oxygen. ..

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Update Time: 2024-07-02

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

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