"Oxygen" The air around us PPT courseware 7

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"Oxygen" The air around us PPT courseware 7

physical properties of oxygen

1. Color, taste and state: Under normal circumstances, it is a colorless and odorless gas.

2. Density: The density is slightly higher than that of air (under standard conditions)

3. Water solubility: not easily soluble in water

4. Three-state changes:

How to check if this is a bottle of oxygen?

Put the wooden stick with sparks into the gas bottle. The wooden stick with sparks will re-ignite, proving that it is a bottle of oxygen.

Sulfur combustion experimental phenomena:

In the air: Emits a weak light blue flame, releases heat, and generates gas with a pungent odor.

In oxygen: emits a bright blue-purple flame, releases heat, and generates gas with a pungent odor.

Sulfur burns in oxygen, why should a small amount of water be left at the bottom of the gas collecting bottle?

Sulfur + oxygen → sulfur dioxide

Dissolve and absorb the generated sulfur dioxide to prevent sulfur dioxide from escaping and polluting the environment.

Charcoal burning experimental phenomena:

In the air: emits red light and releases heat. The gas generated after combustion can turn clear lime water into turbidity.

In oxygen: it emits white light and releases heat. The gas generated after combustion can turn clear lime water into turbidity.

Wire burning experimental phenomena:

In the air: Iron wire cannot burn and red heat occurs.

In oxygen: the iron wire burns violently, sparks are emitted, heat is released, and a black solid is produced.

Textbook P35 discussion:

1. Analyze the experiment and fill in the blanks in the form.

2. What are the common characteristics among the above reactions?

(1) There are two substances participating in the reaction in the reactants.

(2) Oxygen is present in the reactants.

(3) The reaction conditions are all ignition.

(4) The products have only one substance.

(5) are all reactions between solids and gases.

(6) All reactions release heat.

Summary, summary

Oxygen is a gas with relatively active chemical properties. It provides oxygen in oxidation reactions, has oxidizing properties, and is a commonly used oxidizing agent. It can support combustion, react with many substances, and release heat at the same time. The higher the oxygen content, the more intense the combustion.

Oxygen supports combustion, but cannot burn itself! Oxygen supports combustion but is not flammable.

1. Oxygen is a common substance around us. Which of the following statements about oxygen is correct ( )

A. The reaction between a substance and oxygen is an oxidation reaction

B． Fish, shrimp, etc. can survive in water because oxygen is easily soluble in water

C. Oxygen is flammable

D． The reaction of a substance burning in oxygen must be a chemical reaction

2. The properties of substances determine the uses of substances. Which of the following causal relationships is not established ( )

A. Because phosphorus burns to produce white smoke, it can be used to make smoke bombs

B． Because tungsten metal has a high melting point, it is used to make filaments in light bulbs.

C. Because nitrogen is chemically inactive, it can be used for preservatives in food packaging bags.

D． Because oxygen supports combustion, it can be used as fuel

3. A gas collecting bottle is filled with air. Now it is necessary to remove the oxygen without adding other gas components. The available combustible materials are ( )

A. Charcoal B. Iron C. Phosphorus D. Sulfur

Identify oxygen, air, nitrogen, carbon dioxide?

1. Put the burning wood sticks into the gas collecting bottles respectively. The wood sticks burn normally with air; the wood sticks that can make the sticks burn more vigorously are oxygen; the ones that can extinguish the wooden sticks are nitrogen or carbon dioxide.

2. Add a small amount of clarified lime water to the two gas collecting bottles and shake. The thing that makes the lime water turbid is carbon dioxide, otherwise it is nitrogen.

Or: 1. Add a small amount of clarified lime water to the gas collecting bottle and shake it. Carbon dioxide can make the lime water turbid.

2. Then put the burning wood sticks into the remaining gas bottles. The wood sticks burn normally with air; the wood sticks that burn more vigorously are oxygen; the wood sticks that can extinguish the wood sticks are nitrogen.

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For more information about the PPT courseware "Oxygen in the Air Around Us", please click the Oxygen in the Air Around Us ppt tag.

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Update Time: 2024-09-08

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