"Oxygen" The air around us PPT courseware 9

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"Oxygen" The air around us PPT courseware 9

Oxygen test

Insert two wooden sticks with sparks into the two bottles respectively.

Oxygen can rekindle sparks in wood.

Insert two burning sticks into the two bottles.

The more vigorously the wood sticks burn, the more oxygen there is.

1. Physical properties of oxygen

1. Colorless, odorless gas

2. Density (1.429 g/L) is greater than air

3. Boiling point - 183 ℃ Melting point - 218 ℃

Oxygen ← Liquid Oxygen ← Solid Oxygen

(colorless) (light blue) (light blue)

2. Chemical Properties of Oxygen

please think about it

1. There is some water in the bottom of the gas collecting bottle. Why?

2. Why should the burning spoon be immersed in water at the end of the experiment?

Both steps are to absorb sulfur dioxide gas and reduce harmful gas emissions.

Many experiments have proven that substances burn more vigorously in oxygen than in air. Why is this?

The combustion of substances in the air mainly reacts with oxygen in the air. Since the oxygen content in the air is relatively small, combustion in the air is not as vigorous as in oxygen.

Precautions:

1. Thin wire coiled into a spiral shape

2. Tie a match to the lower end of the thin wire. When the match burns out, insert it into a gas bottle containing oxygen.

3. Put some water at the bottom of the gas collecting bottle first

Please think about it?

1. Why is the thin wire coiled in a spiral shape?

Increase the contact area with oxygen

2. Why is a match tied to the lower end of the thin wire?

The purpose is to ignite the wire

3. Why do you put a small amount of water (or spread a layer of fine sand) in the gas collecting bottle before burning the wire?

To prevent splashing melt from exploding the bottom of the bottle

Class exercises

1. Which of the following descriptions of experimental phenomena is correct ( )

A.Charcoal burns in oxygen and emits a bright flame

B. Thin iron wire can burn violently in the air, sending sparks everywhere

C. Phosphorus produces a large amount of white mist when it burns in oxygen.

D. Sulfur burns in oxygen and emits a bright blue-violet flame.

2. Among the following statements about the physical properties of oxygen, which one is correct ( )

A. Liquid oxygen is colorless

B. Oxygen is poorly soluble in water

C. The density of oxygen is slightly less than that of air

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

3. When the following substances burn in oxygen, the bottom of the gas collecting bottle does not need to be padded with a small amount of fine sand or water ( )

A.Charcoal B.Sulfur powder

C. Iron wire D. Red phosphorus

3. Combination reaction (one of the four basic reaction types)

Common characteristics: They are composed of two substances reacting to produce another substance

Concept: a reaction in which two or more substances produce another substance

Expression: A + B ---- C

Emphasis: there is only one product

4. Oxidation reaction

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

Oxygen can provide oxygen in the reaction and is a common oxidizing agent with oxidizing properties.

Tips:

Oxidizing property: The property of providing oxygen.

Oxidant: A substance that provides oxygen.

Slow oxidation

The oxidation reaction proceeds very slowly, without obvious luminescence or heat release, and is even difficult to detect.

Note: Slow oxidation does not necessarily emit light, but it does release heat.

practise

1. Which of the following statements is correct ( )

A. The reaction that produces one substance from two substances is called a chemical reaction.

B. Oxidation reaction refers to the chemical reaction between a substance and oxygen

C. Reactions involving oxygen are not necessarily oxidation reactions

D. Reactions involving oxygen are not necessarily chemical reactions

2. The following reactions are oxidation reactions, but the ones that are not combination reactions are ( )

A. Copper + oxygen ---- copper oxide

B. Acetylene + oxygen ---- carbon dioxide + water

C. Hydrogen + oxygen ---- water

D. Ammonium bicarbonate ---- carbon dioxide + water + ammonia

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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: 2024-10-01

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

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