"Multicomponent Air" Air and Water PPT Courseware 2

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"Multicomponent Air" Air and Water PPT Courseware 2

think

1. What would our world look like if there was no air in the world we live in?

2. The air is all around you. Can you describe its physical properties?

3. Is air a single substance? What are its main components?

1: Composition of air Red phosphorus combustion Experimental principle:

Red phosphorus is fully burned in a closed container, consuming oxygen in the air and producing phosphorus pentoxide solid. The pressure in the container decreases and the water level rises by about 1/5, thus determining the volume fraction of oxygen in the air.

Experimental phenomena:

1. Red phosphorus burns and emits a yellow-red flame.

2. Release a lot of heat

3. Produce a lot of white smoke

4. Generate white solid;

Analysis and induction

Please discuss with your classmates to answer the following questions based on the observed experimental phenomena.

The reason why all the red phosphorus is not burned in the gas cylinder is __________.

After igniting red phosphorus, why do you need to quickly insert the burning key into the gas collecting bottle and tighten the rubber stopper?

After the red phosphorus is extinguished, why do we have to wait until the gas collection bottle cools to room temperature before opening the spring clamp?

Why does the water surface rise after opening the spring clamp? The rising volume of the water surface is the volume occupied by what gas before combustion?

This means that oxygen accounts for approximately ______ of the total volume of air.

Can charcoal, sulfur, etc. be used instead of red phosphorus?

2. Mixtures and pure substances

1. Mixture: A substance like air that is composed of two or more components is called a mixture.

What mixtures do you know?

2.Pure matter:

A substance composed of one component.

Such as: oxygen, carbon dioxide, etc.

Do you also know which substances are pure substances?

Exchange and discussion

In the experiment of measuring the oxygen content in the air, the remaining gas in the gas collecting bottle was mainly nitrogen. Please discuss with your classmates: What properties does this experiment illustrate from the other side of nitrogen?

3. Properties and uses of nitrogen

1. Physical properties: Normally, nitrogen is a colorless, odorless gas that is difficult to dissolve in water.

2. Chemical properties: Nitrogen does not burn and does not support combustion (the chemical properties of nitrogen are very inactive)

3. Uses of nitrogen: 1. Protective gas for welding metals 2. Food packaging to prevent corruption 3. Preparation of nitric acid and nitrogen fertilizer 4. Refrigerant

Class exercises

1. Calculated by volume, the most abundant gas in the air is ( )

A oxygen B nitrogen

C carbon dioxide D rare gas

2. The volume of nitrogen in 100 liters of air is approximately ( )

A 78 liters B 78% C 21 liters D 21%

3. The volume ratio of oxygen to nitrogen in the air is approximately ( )

A 4:1 B 1:4 C 1:5 D 5:1

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"Multicomponent Air" Air and Water PPT Courseware 3:

"Multicomponent Air" Air and Water PPT Courseware 3 1. Composition of Air [Think about it]: 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 Priest.

"Multicomponent Air" Air and Water PPT Courseware:

"Multicomponent Air" Air and Water PPT Courseware Learning Objectives Determination of Oxygen Content in the Air Experiment 1. Red phosphorus combustion experimental phenomenon, text expression, conclusion 2. Reasons for small experimental results 3. Red phosphorus is the key to the success of the experiment The phenomenon of burning in air? ..

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Update Time: 2024-11-21

This template belongs to Chemistry courseware Hunan Education Edition Ninth Grade Chemistry Volume 1 industry PPT template

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