Etilen: Định nghĩa, công thức cấu tạo, tính chất, cách điều chế và ứng dụng

Etilen: Định nghĩa, công thức cấu tạo, tính chất, cách điều chế và ứng dụng
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Ethylene (chemical formula C2H4) is known to be one of the first biogas discovered by man in 1917. They are a common gas used in daily life, appearing right in the family. Friend. So what is ethylene? Let’s learn the definition, structural formula, properties, preparation and application of this compound.

What is ethylene?

Ethylene (also known as Ethylene) is a gas found in hydrocarbons. At the same time, Ethylene is also the simplest alkene (alkene) with the chemical formula C2H4 (or CH2=CH2).

Referring to Etilen, people will immediately think of the use of making bananas ripen quickly. The first known use of ethylene was its ability to stimulate fruit ripening. Soon after, many scientists studied this gas and proved that ethylene is produced from plant components, especially fruits.

Currently, Ethylene C2H4 is used in the plastics industry as a raw material for the preparation of polyethylene. This is an important compound that is widely used in manufacturing.

Structural formula C2H4 - Short: CH2=CH2.  (Photo: Internet Collection)

  • In the structural formula C2H4, there is a double bond between two carbon atoms.
  • In a double bond there is a weak bond. This bond is easily broken in chemical reactions.
  • Open-chain hydrocarbons, whose molecules have a double bond such as ethylene, are called alkenes, and have the general formula CnH2n with n ≥ 2.

What physical properties does ethylene have?

Looking at the structural formula of ethylene, it can be seen that this is a gas, colorless, odorless, lighter than air (d = 28/29), slightly soluble in water. Ethylene is also highly flammable and has a slightly sweet, musky odor.

Learn the properties of ethylene.  (Photo: Internet Collection)

Ethylene is sparingly soluble in water but highly soluble in ether and some organic solvents.

To identify ethylene gas, people use the following methods:

  • Pass ethylene gas through the bromine solution (the solution is orange), observe that the bromine solution loses color.

  • Pass ethylene gas through the potassium permanganate solution, observe that the potassium permanganate solution is discolored.

Chemical properties of ethylene

Ethylene (C2H4) is an unsaturated hydrocarbon in the homologous series of alkenes. Ethylene can react with many substances in many different forms such as: Oxygen, bromine solution, polymerization of ethylene C2H4, … This is a gas that can participate in reactions in many different forms.

Flammability (Reacts with oxygen)

  • Similar to methane, when ethylene burns completely, it produces carbon dioxide (CO2), water vapor (H2O) and the reaction is exothermic.

  • Reaction Equation:

C2H4 + 3O2 → 2CO2 + 2H2O (temperature)

Reaction with Bromine solution

Experiment: Pass ethylene gas through orange bromine solution in a test tube.

Reaction with bromine solution.  (Screenshots)

Phenomena:

  • Initially the bromine solution has a pale skin color
  • After introducing ethylene gas, the bromine solution was discolored.

Comment: Ethylene reacted with bromine in solution. We have the equation for the reaction:

CH2= CH2 (k) + Br2 (dd) → Br – CH2 – CH2 – Br (l)

Conclude:

  • Thus, the weak bond in the double bond is broken and each molecule of ethylene has incorporated an additional molecule of bromine. The above reaction is called addition reaction.
  • In addition to bromine, under the right conditions, ethylene also reacts with some other substances, such as hydrogen and chlorine. In general, substances with double bonds (similar to ethylene) readily participate in addition reactions.

Reaction with chlorine

CH2 = CH2 + Cl2 → CH2=CH2Cl – HCl

Hydrogen addition reaction

C2H4 +H2 → C2H6

Acid addition reaction

CH2= CH2 + HCl (gas) → CH3CH2Cl

C2H4 + HBr → C2H5Br

Water addition reaction (with temperature conditions and acid catalysis)

C2H4 + H2O → C2H5OH

Coincidence

Under the right conditions (temperature, pressure, catalysis), the weak bond in the ethylene molecule is broken, leading to the phenomenon that the ethylene molecules combine to form a molecule of the same size and mass. very large amount, called polyethylene (abbreviated PE).

PE is a solid, non-toxic, insoluble in water, an important raw material in the plastics industry.

…+ CH2 = CH2 + CH2 = CH2 + CH2 = CH2 + … → … – CH2 – CH2 – CH2 – CH2 – CH2 – CH2 –… (catalyzed conditions of pressure, temperature)

This is called a polymerization reaction.

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How to prepare ethylene?

Ethylene is most commonly prepared and applied in two common environments: the laboratory and in industry.

Learn how to prepare ethylene.  (Photo: Internet Collection)

Preparation of ethylene in the laboratory

In the laboratory, ethylene is prepared by heating ethanol with concentrated sulfuric acid according to the scheme:

CH3CH2OH → CH2=CH2 + H2O (H2SO4, temperature)

Preparation of ethylene in industry

Industrially, ethylene is prepared by the separation of hydrogen from the corresponding alkane or by the cracking reaction.

See more:

What role does ethylene play? Featured applications of Etilen

Ethylene is applied and present in many different areas of life. In particular, the application of ethylene is most prominent in specific industries such as biology, industry and agriculture.

Ethylene is used to stimulate fruit ripening.  (Photo: Internet Collection)

In industry

In industry, ethylene is an important raw material that is thoroughly applied:

  • Industrial synthesis of polymers and many other organic substances.

  • It is possible to synthesize various essential organic substances from ethylene such as ethanol, ethylene glycol, etc.

  • Applications in the production of packaging, textiles, electronics.

  • Raw materials in the production of building materials, additives and adhesives.

  • Used for petrochemical industry, derivatives.

In agriculture

  • Ethylene increases the growth of plant cells.

  • Used in stimulating the germination and growth of plants and trees.

  • Helps to increase crop productivity, serving the farming and farming industries

  • In particular, ethylene is used to stimulate fruit ripening.

In biology

  • Ethylene and fruit ripening: Under the action of ethylene, fruit ripens faster. To slow down fruit ripening, ethylene synthesis is limited by gradually withdrawing this gas as the fruit ripens or lowering the temperature and reducing air permeability.

  • Ethylene and shedding: The shedding of plant parts (flowers, fruits, branches, leaves) is initiated by stem breakage. Stem breakage depends on the correlation of ethylene and auxin. Ethylene stimulates and auxin inhibits shedding.

  • Ethylene and its action: Ethylene and auxin also cause induced locomotion in plants, in which auxin acts indirectly through induction of ethylene synthesis.

  • Ethylene and the germination and rejection of some plant species: Ethylene increases the germination rate of some plant species. Sometimes, ethylene is used to promote the germination of potatoes and onions.

  • Ethylene and the induction of flowering: Ethylene is a basic ingredient in the building blocks of the flowering process. Ethylene has been used to inhibit flowering in some cases, however it has an effect on stimulation in pineapple, mango and litchi. For unisexual plants, ethylene has the ability to change the sex of the developing flower…

Distinguish ethylene from ethane, acetylene

To distinguish the simplest substances ethylene, ethane and acetylene, we need to choose a reagent that gives the phenomenon of difference between substances.

Distinguish ethylene from ethane

To distinguish two cylinders containing ethane and ethylene, the reagent is Br2 . solution

Distinguish ethylene from acetylene

To distinguish two cylinders containing ethylene and acetylene, AgNO3/NH3 . can be used as a reagent

Equation: CHO + 2AgNO3 + 2NH3 → CAg≡CAg + 2NH4NO3

Ethylene exercises in chemistry textbook 9 with solutions

From the knowledge about ethylene above, you will apply that knowledge to solve some basic exercises in the following 9 chemistry textbooks.

Apply the theory to do exercises on ethylene.  (Image: Shutterstock.com)

Solving Lesson 1, page 119, Chemistry textbook 9

Calculate the number of single and double bonds between the carbon atoms in the following molecules:

a) CH3 – CH3.

b) CH2 = CH2.

c) CH2 = CH – CH = CH2.

Suggested answer:

a) CH3-CH3 has a single C-C bond.

b) CH2 = CH2 has 1 double bond: C = C.

c) CH2 = CH – CH = CH2 has 2 double bonds: C = C; 1 single bond: C – C.

Solve lesson 3 of Chemistry textbook 9 page 119

State a chemical method for removing ethylene gas from the methane gas to obtain pure methane.

Suggested answer:

Pass the mixture through a solution of excess bromine, then ethylene reacts to form dibromethane, which is liquid that stays in solution and only methane escapes.

CH2 = CH2 + Br2 → Br – CH2 – CH2 – Br.

Solving Lesson 4, page 119, Chemistry textbook 9

To burn 4.48 liters of ethylene gas it is necessary to use:

a) How many liters of oxygen?

b) How many liters of air contain 20% by volume of oxygen? Know the volumes of the gases measured at standard conditions.

Suggested answer:

a) Equation for the combustion of ethylene:

C2H4 + 3O2 → 2CO2 + 2H2O

nC2H4 = 4.48/22.4 = 0.2 mol.

According to the equation: nO2 = 3 x nC2H4 = 0.2 x 3 = 0.6 mol.

VO2 = 0.6 x 22.4 = 13.44 liters.

b) Air volume = (13.44 x 100)/20 = 67.2 liters.

Ethylene exercises for students to practice on their own

In addition to the textbook exercises, here are some exercises that Kênh Văn Hay synthesizes so that the children can practice together:

Question 1: Ethylene gas is mixed with CO2 impurities, show the chemical method to obtain pure ethylene?

Question 2: What is the mass of poliethylene obtained by polymerizing 1 mole of ethylene (with an efficiency of 80 %)?

A. 35.0 grams.

B. 14.0 grams.

C. 28.0 grams.

D. 22.4 grams.

Question 3: Burn V liters of ethylene gas completely at standard conditions. Then, the reaction products were passed through the flask containing the excess of clear lime water and 10 grams of precipitate was obtained. What is the value of V?

A. 1.12 liters.

B. 1.68 liters.

C. 2.24 liters.

D. 3.36 liters.

Question 4: The chemical commonly used to distinguish methane and ethylene is

A. H2.

B. O2.

C. Br2.

D. CO2.

Question 5: Passing 5.6 liters of a gas mixture under standard conditions including: methane and ethylene through a container with excess bromine, the volume of the flask increases by 2.8 grams. The volume of methane gas (dktc) in the mixture is

A. 0.336 liters.

B. 3,360 liters.

C. 0.224 liters.

D. 2,240 liters.

Question 6: The polymerization of 14 grams of ethylene (with 100% yield) under suitable conditions, the mass of poliethylene is obtained.

A. 7 grams.

B. 14 grams.

C. 28 grams.

D. 56 grams.

Question 7: Which of the following substances can discolor bromine solution under normal conditions?

A. CO2.

B. C2H4.

C. CH4.

D. C2H5OH.

Question 8: For 11.2 liters of ethylene (dktc) react with water with sulfuric acid (H2SO4) as a catalyst, yielding 9.2 grams of ethyl alcohol. The reaction yield is:

A. 40%

B.50%

C.45%

D.55%

Question 9: Completely burn 2.24 liters of organic compound A belonging to the same ethene homologous series, then guide the combustion products through flask 1 containing concentrated H2SO4 and flask 2 containing excess Ca(OH)2 respectively. See volume 1 increased by 5.4 grams. The molecular formula of A is

A. C3H6.

B. C4H8.

C. C5H10.

D. C2H6.

Question 10: Passing 2.8 liters of a mixture of methane and ethylene (at dtc) through the excess of bromine solution, 4.7 grams of dibromethane are obtained. The volume percent of methane in the original mixture is

A. 20%.

B. 40%.

C. 80%.

D. 60%.

Question 11: Let V liters of a gas mixture consisting of CH4 and C2H4 pass through a bromine solution and see that 16 grams of bromine react. On the other hand, burning V liters of the above mixture will yield 6.72 liters of CO2 and 7.2 grams of water. Calculate V and % by volume of CH4 in the initial mixture (knowing the measured volumes at ctc)

A. 4.48 liters and 50%.

B. 6.72 liters and 75%.

C. 4.48 liters and 75%.

D. 6.72 liters and 50%.

Question 12: Burning V liters of ethylene yields 9 grams of water vapor. The sufficient volume of air needed at tc is (knowing O2 accounts for 20% of the air volume)

A. 44.8 liters.

B. 56.0 liters.

C. 16.8 liters.

D. 84.0 liters.

Question 13: For a mixture of 5.6 liters of CH4 and C2H4 to react completely with 5% bromine solution, there are 400 grams of reaction solution. The volume percentages of CH4 and C2H4 in the initial mixture are

A. 30% and 70%.

B. 40% and 60%.

C. 50% and 50%.

D. 25% and 75%.

Question 14: In the laboratory, a small amount of ethylene is prepared

A. from petroleum cracking gas

B. from ethyl alcohol

C. from ethane gas C2H6

D. from the reaction of carbon with hydrogen

Question 15: Ethylene has the following chemical properties:

A. Participate in addition reactions, polymerization reactions, drug reactions and combustion reactions.

B. Only participates in substitution reactions and reacts with potassium permanganate solution.

C. Only participates in the combustion reaction.

D. Only participate in addition reactions, polymerization reactions, do not participate in combustion reactions.

The above article has provided full information about the definition, structural formula, properties, preparation and application of ethylene. Hopefully this information will help you gain more useful knowledge and apply them in learning as well as in practice.

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