"Oxygen" The air around us PPT courseware 4

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"Oxygen" The air around us PPT courseware 4

observe, think

Observe the oxygen in the gas cylinder and describe its color and state.

Think about it, does oxygen smell?

Can oxygen dissolve in water?

Question: How do fish breathe in water? Where does the oxygen it breathes come from?

What can be inferred from this about the solubility of oxygen?

1. Physical properties of oxygen

(1) Colorless, odorless gas

(2) Density 1.429g/L, larger than air

(3) Not easily soluble in water (1L of water dissolves 30mL of oxygen)

(4) Three-state transformation: under 101kPa

2. Chemical Properties of Oxygen

Generally refers to the flammability, combustion-supporting property, oxidizing property, reducing property, corrosiveness, toxicity, etc. of the substance.

Oxygen can rekindle wooden sticks with sparks, indicating that oxygen can support combustion.

Note: Oxygen cannot be burned.

Test oxygen: Insert the wooden stick with sparks into the gas collecting bottle. If the wooden stick re-ignites, it proves that the bottle contains oxygen.

do you know?

Things to note for a successful experiment:

①The function of matches: to ignite the iron wire

② Wrap the wire into a spiral: increase the contact area with oxygen

③When the match is about to burn out, put the iron wire into the oxygen bottle: to prevent the match from consuming too much oxygen and preventing the iron wire from burning smoothly.

④Put a small amount of water in the gas collecting bottle in advance or spread a thin layer of fine sand at the bottom of the bottle to prevent high-temperature melt from splashing down and exploding the bottom of the bottle.

⑤Use sandpaper to remove the rust on the wire surface

Determination of oxygen content in air

When doing this experiment, would it be okay to choose sulfur, carbon, candle, iron or magnesium as the drug?

① Sulfur, carbon, and candles cannot be selected: because they burn in the air, consume oxygen and generate new gases, they cannot form a pressure difference, and water cannot be sucked back.

② Iron or aluminum cannot be selected: because they cannot burn in air.

③ Magnesium cannot be selected: because it burns in the air and consumes oxygen, and it can also react with nitrogen and carbon dioxide in the air, which will cause far more than one-fifth of the water to enter.

Drug selection: It can burn in the air, and only reacts with oxygen, and the product is gas-free (red phosphorus is the most suitable).

Targeted exercises

1. Which of the following descriptions about the properties of oxygen is incorrect ( )

A. Under normal circumstances, oxygen is a colorless and odorless gas

B. Oxygen can become liquid or solid at low temperature and high pressure

C. Oxygen is easily soluble in water

D. Oxygen is a gas with relatively active chemical properties.

2. Which of the following statements is correct ( )

A. Charcoal produces black solids after burning

B. The wire is inserted into a gas bottle containing oxygen and burns violently

C. Red phosphorus cannot burn in air

D. Sulfur generates pungent smelling gas after burning.

3. Among the following properties of substances, which ones are chemical properties ( )

A. Color, state B. Density, hardness

C. Oxidizing, flammable D. Melting point, boiling point

4. The phenomenon that must occur when a substance burns in air is ( )

A. Generate solid substances B. Generate gas substances

C. Release heat D. Emit white light

5. Among the following substances, which one does not contain oxygen ( )

A.Carbon dioxide B.Natural water

C. Clean air D. Liquid oxygen

5. Slow oxidation:

An oxidation reaction that proceeds very slowly or even imperceptibly is called slow oxidation.

For example: the respiration of animals and plants, the decay of food, the brewing of wine and vinegar, the decay of farmyard manure, the rust of iron and copper

6. Spontaneous combustion:

Spontaneous combustion caused by slow oxidation.

For example: white phosphorus spontaneous combustion, straw spontaneous combustion, etc.

Not all slow oxidation will trigger spontaneous combustion.

General conclusion: 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.

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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: 2024-11-23

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

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