"Understanding Organic Compounds" Organic Compounds PPT (Properties of Alkanes in Lesson 2)

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"Understanding Organic Compounds" Organic Compounds PPT (Properties of Alkanes in Lesson 2)

Part 1: Essential knowledge and foundation of literacy

1. Properties of Alkanes

1. Physical properties (as the number of carbon atoms in the molecule increases)

(1) Melting and boiling points: gradually _____;

(2) State: from gaseous state → liquid state → solid state, among which alkanes with carbon atoms less than or equal to 4 under normal temperature and pressure are in gaseous state;

(3) Density: Gradually _____ and are all ___ denser than water and _____ denser than water.

2. Chemical properties

Normally, alkanes are relatively stable and do not react with strong oxidants such as strong acids, strong bases or potassium permanganate. However, it can burn under certain conditions, decompose at higher temperatures, and undergo substitution reactions with chlorine, etc.

(1) The general combustion formula of alkanes is CnH2n+2+______O2 _____________.

[Micro Thoughts] The air contains methane: 5% ~ 15%, and the oxygen contains methane: 5.4% ~ 59.2%. It will explode when encountering sparks. Most gas explosions in coal mines are caused by methane gas explosions. If you were a coal miner, what measures would you take to prevent a gas explosion when you were mining in the mine?

Tips: Ventilate in time and avoid open flames.

(2) Taking methane as an example to explore the substitution reaction of alkanes

Experimental phenomena

Device A: The color of the gas in the test tube gradually _____; there is _________ on the inner wall of the test tube, a small amount of white mist in the test tube, and the liquid level in the test tube is _____, and there is solid precipitation in the water tank.

B device:___________

Experimental results

The chemical reaction between CH4 and Cl2 requires _____. The relevant chemical equation:

CH4+Cl2 CH3Cl+HCl (monochloride),

CH3Cl+Cl2 CH2Cl2+HCl (dichloride),

CH2Cl2+Cl2 CHCl3+HCl (trichloride),

CHCl3+Cl2 CCl4+HCl (tetrachloride).

【Micro thinking】

If a hydrogen atom in a methane molecule is replaced by a chlorine atom, will the resulting CH3Cl still have a tetrahedral structure?

Tip: 3 H and 1 Cl in CH3Cl are still located at the 4 vertices of the tetrahedron, and it is still a tetrahedral structure.

2. Properties of organic matter

1. Physical properties: Most organic substances have relatively low melting points, are difficult to dissolve in water, and are easily soluble in organic solvents such as gasoline, ethanol, and benzene.

2. Chemical properties: Most organic substances are easy to burn and will decompose when heated; the chemical reactions of organic substances are relatively complex and often accompanied by side reactions. Many reactions need to be carried out under the conditions of heating, light or catalysts.

【Situation·Thinking】

"Shui Tiao Ge Tou: When Will the Bright Moon Come" was written by Su Shi, a great writer in the Song Dynasty, when he was in Mizhou during the Mid-Autumn Festival in 1076 AD. This poem is based on the rise of the moon and the relationship between Su Che and his brother Su Che who have not seen each other for seven years. It revolves around the Mid-Autumn Moon and unfolds imagination and thinking. It incorporates the joys and sorrows of the world into the philosophical pursuit of the universe and life, reflecting the author's The complex and contradictory thoughts and feelings also show the author's love for life and positive and optimistic spirit.

(1) Organic matter is everywhere in production and life. Looking at the picture above, which items contain organic matter?

Tip: Flowers, plants, trees, clothing, and alcohol (ethanol) all contain organic matter.

(2) Based on the analysis of the physical and chemical properties of common organic compounds in life, what are the general characteristics?

Tips: The melting and boiling point is low, easy to burn, etc.

Understanding organic compounds PPT, part 2: key abilities and literacy formation

Knowledge point 1: Representation method of organic matter

[Key points to clarify doubts]

【Think·Discussion】

(1) The ball-and-stick model of a hydrocarbon is ______. Try to write down its molecular formula and simplified structural formula.

Tip: The molecular formula is C4H10, and the simplified structural formula is CH3CH2CH2CH3.

(2) Combined with the chemical bond theory to analyze the molecular structure of organic matter, is it true that atoms are connected to each other through "sticks" like the ball-and-stick model? What does the "stick" in the ball-and-stick model represent?

Tip: Atoms in organic molecules are bonded to each other through chemical bonds. The "stick" in the ball-and-stick model represents chemical bonds.

【Case Demonstration】

[Typical example] n-hexane is an excellent organic solvent. Its ball-and-stick model is _________. Which of the following statements is correct ()

A. The molecular formula of n-hexane is C6H12

B. There are three types of monochlorinated products of n-hexane

C. n-hexane can undergo a substitution reaction with bromine to cause bromine water to fade.

D. There is only one isomer of n-hexane containing 4 carbon atoms in the main chain.

[Problem-solving guide] To answer this question, you need to pay attention to the following two points:

(1) Determine the molecular formula and simplified structural formula of organic matter based on the ball-and-stick model.

(2) Determine the categories and typical properties of organic matter based on their structure.

【Migration·Application】

1. Each of the following figures can represent the molecular structure of methane. Which one better reflects its true existence ()

[Analysis] Choose D. These forms can all represent methane molecules. Among them, the schematic diagram of the molecular structure, the ball-and-stick model and the space-filling model can all reflect the spatial configuration of methane molecules, but the space-filling model can more vividly express the positions of H and C in the methane molecule. and proportion. The electronic formula only reflects the bonding situation of the outermost electrons of the atom.

2. (2019·Xingtai Senior High School Test) There are 4 kinds of hydrocarbons with carbon skeletons as shown in the figure. The following statement is correct ()

A.a and b are isomers of each other

B.b and c are homologues of each other

C.b and c are isomers of each other

D. Only b and c can undergo substitution reaction

[Analysis] Choose B. The molecular formula of a is C4H8, and the molecular formula of b is C4H10, which are not isomers of each other. A is wrong; the molecular formula of b is C4H10, and the molecular formula of c is C5H12. They are both alkanes with similar structures, but they differ by one CH2 atomic group. Homologues, B is correct, C is wrong; d is that cyclobutane can also undergo substitution reaction, D is wrong.

Knowledge Point 2: Understand the characteristics of alkane substitution reactions

[Key points to clarify doubts]

1. Summary of the substitution reaction between methane and chlorine

【Think·Discussion】

(1) When methane and chlorine react, how many products are obtained? What is the type of reaction?

Tip: There are 5 kinds of products, namely CH3Cl, CH2Cl2, CHCl3, CCl4, HCl; substitution reaction.

(2) Can pure CH3Cl be produced by mixing CH4 and Cl2 at a volume ratio of 1:1?

Tip: The reaction of CH4 and Cl2 is a chain reaction. It is impossible for only the first step of the substitution reaction to occur. The product is a mixture, that is, a mixture of four organic substances, CH3Cl, CH2Cl2, CHCl3 and CCl4, and hydrogen chloride. The yield of CH3Cl is low, so Pure CH3Cl cannot be produced by mixing CH4 and Cl2 in a volume ratio of 1:1.

【Case Demonstration】

[Typical example] An extracurricular activity group used the device as shown in the picture to explore the reaction between methane and chlorine. According to the meaning of the question, answer the following questions:

(1) The conditions for the reaction of CH4 and Cl2 are ________; if exposed to direct sunlight, it may cause ____________________.

(2) Experimental phenomena that can be observed in the experiment include: oily droplets appear on the inner wall of the measuring cylinder, a small amount of solids precipitate in saturated brine, ________, ________, etc.

(3) The chemical formula of the oily droplets generated in the experiment is ___________, where _________ is an important solvent in industry.

(4) The reason why saturated salt water is used instead of water is __________________.

[Problem-solving guide] To answer this question, you need to pay attention to the following two points:

(1) Pay attention to the conditions of organic reactions. The same substance may react differently or not react under different conditions.

(2) Pay attention to the reaction method. Similar organic substances react in the same way under the same conditions.

[Analysis] CH4 and Cl2 can react with light to produce CH3Cl, CH2Cl2,

CHCl3, CCl4, HCl, as the reaction proceeds, Cl2 is continuously consumed, and the yellow-green color gradually disappears. And because the generated CH2Cl2, CHCl3, and CCl4 are colorless oily liquids at room temperature, there are oil droplets on the inner wall of the measuring cylinder. Because the generated HCl is easily soluble in water, the pressure in the measuring cylinder decreases and the liquid level in the measuring cylinder rises. After HCl is dissolved in water, the Cl- concentration in the solution increases, causing NaCl solid to precipitate.

Understanding organic compounds PPT, part 3: knowledge association·literacy application

【Core Integration】

【Literacy transfer】

1. In the current home appliance market, fluorine-free refrigerators are called green refrigerators. Its major improvement is that it does not use Freon-12 but uses a new refrigerant (R-134a) as the refrigerant. The correct statement about Freon-12 (CCl2F2) is ()

A. There are two isomers

B. It is a planar molecule

C. There is only one structure

D. There are four isomers

[Analysis] Choose C. CCl2F2 can be regarded as the replacement of two hydrogen atoms of CH2Cl2 by two fluorine atoms, so C is chosen.

2. (2019·Nanping High School Grade 1 Test) Which of the following relationships among the following substances is incorrect ()

A.CH3CH2CH2CH2CH3 and are isomers of each other

B. Dry ice and ice are the same substance

C.CH3CH3 and CH3CH2CH3 are homologues of each other

D.12C and 14C are isotopes of each other

3. (2019·Baoding High School Detection) Propane (C3H8) is commonly used as a fuel for barbecues, portable stoves and motor vehicles. It is often used to drive buses and taxis, and is also used as fuel for heating and cooking in RVs and camping. Sports torches also generally use propane as fuel.

(1) What are the advantages of using propane as fuel?

(2) How many monochlorine substitution products are there for propane?

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Update Time: 2024-10-02

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