Grade 9 Chemistry Equation Water in Nature The air around us Step into the knowledge tree of the wor

Introduction Chemistry makes the world more colorful.

Unit 1 Entering the world of chemistry.

Topic 1: Changes and properties of matter.

Topic 2 Chemistry is an experiment-based science.

Topic 3 Walk into the chemistry laboratory.

Unit 2 The air around us.

Issue 1: Air.

Issue 2 Oxygen.

Issue 3: Oxygen production.

Unit 3 Water in Nature.

Topic 1: Composition of water.

Topic 2: Molecules and atoms.

Issue 3: Water purification.

Issue 4: Caring for water resources.

Expansive Topics The lightest gas.

Unit 4 The Mystery of the Composition of Matter.

Issue 1: Composition of atoms.

Topic 2 Elements.

Issue 3: Ions.

Topic 4 Chemical formulas and valencies.

Unit 5 Chemical Equations.

Topic 1: The Law of Conservation of Mass.

Topic 2: How to write chemical equations correctly.

Topic 3: Simple calculations using chemical equations.

Unit 6 Carbon and Carbon Oxides.

Topic 1 Diamond, graphite and C60

Issue 2: Research on carbon dioxide production.

Issue 3 Carbon dioxide and carbon monoxide.

Unit 7 Fuel and its utilization.

Issue 1: Combustion and extinguishing of fires.

Issue 2 Fuel and heat.

Issue 3: Environmental impact of fuel use.

Expansive Topics: Comprehensive utilization of oil and coal.

Attached are the rules for the use of commonly used instruments and drugs in junior high school chemistry experiments.

Appendix A comparison table between Chinese and English for some nouns.

Postscript to the periodic table.

The third unit is the knowledge points of "Water in Nature".

1. Water 1. Composition of water:

1) Experiments on electrolysis of water.

a.Installation: Water electrolyzer.

b.The type of power supply --- direct current.

c.The purpose of adding sulfuric acid or sodium hydroxide --- to enhance the conductivity of water.

d.Chemical reaction: 2H2O === 2H2 + O2

The position of the negative electrode is generated, and the positive electrode is generated.

Volume ratio 2:1

The mass ratio is 1:8

f.Inspection: O2 --- gas outlet with a spark on the spark --- rekindle the strip.

H2 --- a burning wooden strip is placed at the outlet to --- the gas burns, producing a pale blue flame.

2) Conclusion: Water is composed of hydrogen and oxygen. A water molecule is made up of 2 hydrogen atoms and 1 oxygen atom.

In chemical change, molecules are divisible but atoms are inseparable.

Example: According to the chemical formula H2O of water, you can read the information.

The meaning of the chemical formula H2O

Indicates a substance like water.

Indicates the composition of this substance Water is made up of the elements hydrogen and oxygen.

Represents a molecule of this substance, a molecule of water.

Represents the composition of a molecule of this substance A water molecule is made up of two hydrogen atoms and one oxygen atom.

2. Chemical properties of water.

1) Energized decomposition 2H2O=== 2H2 +O2

2) Water can react with alkaline oxides to form alkaline alkali (soluble base), for example: H2O + CaO==Ca(OH)2

3) Water can react with acidic oxides to form acids, for example: H2O + CO2==H2CO3

3. Water pollution

1) Water resources.

a Seventy-one per cent of the Earth's surface is covered by water, but less than 1 per cent of fresh water is available for human use

b The oceans are the largest reservoirs on Earth. Seawater contains more than 80 elements. The most abundant substance in seawater is H2O, the most metallic element is Na, and the most abundant element is O.

c The distribution of water resources in China is uneven, and the per capita amount is small.

2) Water pollution.

a. Water pollutants: industrial "three wastes" (waste residue, waste liquid, waste gas); Unreasonable application of pesticides and fertilizers.

Arbitrary discharge of domestic sewage.

b. Prevent water pollution: the three industrial wastes should be treated and discharged up to the standard, and zero discharge should be advocated; Domestic sewage should be treated centrally and discharged up to standard, and zero discharge should be advocated; rational application of pesticides and chemical fertilizers, and the use of farm fertilizers is advocated; Strengthen water quality monitoring.

3) Take care of water resources: save water and prevent water pollution.

4. Water purification.

1) The purification effect of water from low to high is static, adsorption, filtration, and distillation (all physical methods), among which the operation with the best purification effect is distillation; The water purifier that has both filtration and adsorption is activated carbon.

2) Hard water vs. soft water definition.

Knowledge Points:

1. Physical properties of water: pure water is a liquid with no color, no smell and no taste, at 101kpa, the freezing point of water is 0, the boiling point is 100, and the density is the largest at 4, which is 1g per cubic centimeter (1g ml), and the volume expands when water freezes, so the density of ice is smaller than that of water, and it can float on the water surface.

2. Composition of water: Through the electrolysis of water, it can be seen that water is composed of hydrogen and oxygen.

3. Properties of hydrogen:

Under normal circumstances, hydrogen is a colorless and odorless gas, difficult to dissolve in water, and can become a colorless liquid and snowflake-like solid when cooled, and the density of hydrogen under standard conditions is the lightest gas in nature.

Chemical properties) hydrogen is chemically stable at room temperature, but can react with a variety of substances under heating or ignition conditions.

Flammability: Pure hydrogen burns quietly in oxygen, emitting a pale blue flame that ignites a mixture of hydrogen and oxygen (or hydrogen impurity) can occur**.

Reducibility: Hydrogen can seize the oxygen in some oxygen-containing compounds, so that the oxygen-containing compounds undergo a reduction reaction, and hydrogen is used as a reducing agent.

4. Elemental, compound, oxide.

Elemental: A pure substance composed of the same element is called elemental.

Compounds: Pure substances composed of different elements are called compounds.

Oxide: A compound composed of two elements, one of which is oxygen, is called an oxide.

Actually, what do you want to ask?

15 questions, (3) 5mg2+ (4) H2O oxygen is minus 2 (5) H2O2

6）fe2o3

7）na2co3

16 questions 17 are a mixture: 4 and 5

Belongs to the purity and 6

It belongs to the compound and 6

Elemental: 2

Belongs to oxides: 1 and 6

18. (1) ab (2) c (3) adsorption of impurities suspended in water (or adsorption sedimentation) (4) mixture.

19. (1) A glass rod B filter paper C funnel D beaker.

2) The filter paper is punctured, the filtrate is higher than the edge of the filter paper, and the small beaker is not clean.

18. (1), A and B raw water is colloidal, and suspended solids such as sediment can be turned into precipitate after adding alum. Then filter.

2) c, chlorine is dissolved in water and reacts with water to form hypochlorous acid, which can kill bacteria.

3) There are suspended solids such as sediment in the raw water, which is colloidal, and the alum is an electrolyte after adding alum, which can make the colloid precipitate.

4) Tap water is still a mixture, because it also dissolves minerals or chemicals and products added when purifying water.

Grade 9 Chemistry Book 1 People Teach Oak Reputation The Water Beam Limb in Nature Review Fictional Draft.