Practical work obtaining ethylene, the study of its properties. Lesson summary on the topic "obtaining ethylene and experiments with it"

Tasks. 1. Get ethylene from ethyl alcohol.

2. Carry out characteristic reactions for ethylene as a representative of saturated hydrocarbons.

Equipment. Ethylene apparatus, test tube rack, glass tubes with drawn end, splint, china plate or cup, sand cup, laboratory rack, burner, matches, spirally coiled beaker copper wire, which must be inserted into the gas outlet tube.

Substances. Ethanol, sulphuric acid(conc.), solution bromine water and a pink solution of acidified potassium permanganate, washed and calcined river sand.

Completing of the work

1. Obtaining ethylene. Assemble the device for obtaining ethylene (Fig. 22.6) and check it for leaks.

To obtain ethylene, place 1.5 ml of ethyl alcohol in a test tube, then carefully add 4 ml of concentrated sulfuric acid and add a little calcined sand to the mixture. Close the test tube with a stopper with a gas outlet tube and fix the device in a tripod.

2. Pour 2 ml of solutions of bromine water and potassium permanganate into two test tubes. Heat the mixture in the device for obtaining ethylene to a boil and, without ceasing to heat, but without overheating, lower the end of the gas outlet tube first into

test tube with bromine water and then into a test tube with a solution of potassium permanganate.

What are you observing? Write Equations chemical reactions: a) obtaining ethylene from ethyl alcohol; b) interaction of ethylene with bromine water.

Point the end of the gas outlet tube of the device up and set fire to the escaping ethylene with a torch. Note the nature of the flame. Place a porcelain plate or bowl into the ethylene flame for a few seconds. What are you observing?

Blow air through a glass tube with a retracted end into the middle part of the ethylene flame. How does the brightness of the flame change? Why? Write an equation for the combustion reaction of ethylene.

Getting ethylene.

Concentrated sulfuric acid has the ability to take water from other substances. This property is used to obtain ethylene.

Water partially condenses on the walls of the test tube and rolls back into the solution. Ethylene escapes through a gaseous tube. properties of ethylene.

Lesson topic: Qualitative determination of carbon in organic substances. Obtaining ethylene and studying its properties.

Lesson goals.

Educational:

Ensure the consolidation of knowledge about the chemical properties of saturated and unsaturated hydrocarbons;

Experimentally confirm theoretical knowledge about laboratory methods for producing ethylene and its interaction with substances;

Observation of chemical phenomena.

Developing:

Formation of practical skills and skills in handling laboratory equipment;

Develop research skills to observe, analyze, draw conclusions.

Educational:

Development cognitive interest to the study of chemistry;

Fostering a culture of experimentation and compliance with safety regulations.

Class type: a lesson in the formation and improvement of skills and abilities.

Type of occupation: laboratory work;

Methodological support: instructional map for execution laboratory work No. 7, Power Point presentation.

Equipment: multimedia projector, computer, set of reagents for performing laboratory work No. 7.

The lesson is accompanied by a presentation. Attachment 1

I. Organizational moment

Greeting, checking absentees, checking students' readiness for class.

II. Reporting the topic of the lesson, setting the goals of the lesson

Today we are starting to carry out Laboratory work No. 7, on the topic: "Qualitative determination of carbon in organic substances. Obtaining ethylene and studying its properties."

The purpose of our lesson: to reveal the properties of saturated and unsaturated hydrocarbons using characteristic chemical reactions. To master the skills of obtaining ethylene in the laboratory.

Listen carefully to the parable and draw your own conclusions:

In very ancient times, there lived an old gardener at the court of the Chinese emperor. Flowers and fruits from the imperial gardens were famous throughout China. A pear tree grew in the garden, which bore fruit once every ten years, and only then did the pears ripen when it was a warm summer. One spring, the emperor called his gardener and ordered that he bring him ripe pears in the fall. And he promised to reward him with gold: "I will give you as much gold as the pears that you bring me will weigh. And if you do not fulfill it, I will order you to be executed."

The summer turned out to be cold, there was no hope that the pears would ripen. But the gardener removed the unripe pears, laid them out in his room, and began to fumigate them with incense. The pears were full, turned amber yellow and smelled of honey. But the gardener did not carry the pears to the emperor, but distributed them to the children and then disappeared. The secret to ripening pears disappeared with him.

Many centuries passed before the composition of incense smoke was tested. It turned out that in its smoke there is a colorless light gas - ethylene. It is currently used for fruit ripening. What are other uses for ethylene?

(Suggested answer: Ethylene is used in the manufacture of rubber, solvents, ethyl alcohol; in the polymerization of ethylene, polyethylene is obtained - a synthetic high molecular weight substance.)

III. Checking the theoretical knowledge of students

Frontal survey of students:

1. Which of these substances are isomeric with each other?

(Answer: a, c.)

2. Which word is superfluous in the series: methane, pentane, butene, hexane, octane, decane.

(Answer: butene.)

3. Correct the mistake in the structure of the molecule and name the alkene:

3-methyl-4,7-diethylnonene-4)

4. Name the alkene of the following structure:

(Answer: 6-methylheptene-3.)

5. How is ethylene obtained in the laboratory, write down the reaction equation on the board?

(Suggested answer: Dehydration of alcohols by heating and using H 2 SO 4 as a catalyst.

Reaction equation: )

6. Why unsaturated hydrocarbons chemically more active than the limit?

(Suggested answer: Unsaturated hydrocarbons are chemically more active due to the presence of multiple bonds. "Pi" - the bond is less strong than the "sigma" bond, so it is easily destroyed by various reagents)

7. Add a reaction:

What substances can be identified using this reaction

The reaction with bromine water is a qualitative reaction for all unsaturated hydrocarbons.)

8. What reaction products are formed during the complete oxidation of hydrocarbons?

(Answer: With the complete oxidation of hydrocarbons in excess oxygen, carbon dioxide CO 2 and water H 2 O.)

9. Insert missing words:

When substances of the HX type, where X \u003d gplogen, - OH group, are attached to asymmetric alkenes, the hydrogen atom is attached to the atom ... y ... of the bond associated with ... the number of atoms ....

(Answer: carbon; multiple (double); largest; hydrogen)

10. Complete the sentence:

Polymerization is the process of combining identical molecules (monomers), which proceeds due to the breaking of multiple bonds, with the formation of ....

(Answer: high molecular weight compound (polymer).)

Some students receive written assignments: (Appendix 2)

IV. Current briefing - presentation of safety regulations using a presentation.

Before you start working on your own, you need to familiarize yourself with the safety rules:

1. Be careful when working with heating devices.

2. Light the spirit lamp, not tilting it to another spirit lamp, but bringing the lit match to the wick of the spirit lamp.

3. Extinguish the spirit lamp by covering it with a cap.

4. When working with reagents, be careful not to allow contact with clothing and skin.

In this lab, for the first time, you are exposed to liquids of organic origin, which easily enter the body in the form of vapors through the skin. Vapors tend to irritate the upper respiratory tract, mucous membranes of the eyes and nose.

5. In order to avoid burns of the mucous membranes, do not bring the reagents to the face, taste them.

v. Independent work students

Each of you received an instruction card for doing lab #7. (Appendix 3). Your task is to study the instruction card in detail: to understand what goals you face when doing this work; what skills and abilities you need to acquire in the course of the work. Check whether the set of reagents corresponds to the one stated in the list of instruments and reagents. Once again, pay attention to the safety regulations. Carefully study the methodology for conducting experiments, and do the experiments. Complete all entries in the notebook in accordance with the requirements in the instruction card.

VI. Final reports of students on the work done

Pay attention to the paragraph of the instructional card "summing up". After you have done all the experiments and filled out the table with the data, proceed to the final task.

Summarizing.

1. Explain why, when burning flour, a black charred mass is formed, because organic substances decompose into water and carbon dioxide when burned?

(Suggested answer: a black mass indicates the formation of carbon, this indicates that an incomplete oxidation reaction has occurred, that is, with a lack of oxygen.)

2. What role does concentrated sulfuric acid play in the production of ethylene from ethyl alcohol.

(Suggested answer: Concentrated sulfuric acid acts as a catalyst for this process.)

3. Write the equation for the reaction of ethylene with iodine water in structural form.

4. Explain why ethylene discolors potassium permanganate solution.

(Suggested answer: A solution of potassium permanganate becomes colorless when exposed to ethylene because dihydric alcohols (diols) are formed during the reaction - colorless substances.)

Everyone must provide a report on the work done in the form of: a competently designed notebook, a completed table with data on the experiments done, and the completed final task from the instruction card.

(Additional questions are asked at the instructor's discretion.)

VII. Summing up the lesson

If anyone has any questions please feel free to ask. Do you understand everything? Lesson grades.

VIII. Homework

Review the textbook material from pages 189-221.

Make a chain of transformations using the studied material on the topics: "Alkanes", "Alkenes", "Alkadienes", "Alkynes".

Practical work No. 1 "Obtaining ethylene and studying its properties"

Objective: obtain ethylene and study its chemical properties.

Reagents and equipment: laboratory stand, stand with test tubes, cork with gas outlet tube, video film “Production of ethylene”, spirit lamp, matches, H solutions 2 SO 4 , KMnO 4 , bromine water.

Progress

Experience 1. Obtaining ethylene

In a test tube with 2 ml of ethanol C 2H5 OH add 6 ml concentrated sulfuric acid H 2 SO 4 . Pour 1 spoon of calcined sand into the test tube, close the cork with a gas outlet tube, fix it in a tripod and start heating.

Note the changes in the test tube with the reaction mixture. Write the reaction equation for the production of ethylene using the abbreviations structural formulas. Draw a conclusion from which substances ethylene can be obtained in the laboratory.

Experience 2. Interaction with bromine

Immerse the end of the gas outlet tube into a test tube with 2 ml of bromine water (bromine solution Br 2 in water).

How did the color of bromine water change? Write the reaction equation using the abbreviated structural formulas. Determine if there is a double bond in the ethylene molecule.

Experience 3. Interaction with potassium permanganate

Immerse the end of the gas outlet tube into a test tube with 2 ml of potassium permanganate KMnO 4 .

How did the color of the potassium permanganate solution change? Write the reaction equation using the abbreviated structural formulas. Conclude whether there is a multiple bond in the ethylene molecule.

Experience 4. Combustion of ethylene

Ignite the escaping gas.

What color does ethylene burn? Write the reaction equation using empirical formulas. Conclude what substances are formed as a result of the combustion of alkenes.

Registration of work

Fill in the table according to the results of the experiment:

Write down the general conclusion on practical work.

Conclusion: ethylene in the laboratory can be obtained by the interaction of ___________; Ethylene is a __________ hydrocarbon.

On the topic: methodological developments, presentations and notes

Practical work "Obtaining ammonia and studying its properties"

Practical work "Obtaining ammonia and studying its properties" Instructions for practical work, report format, Additional tasks to the topic....

Practical work "Obtaining ammonia and studying its properties."

During practical work, they must show the ability to compose technological map;Ø apply theoretical knowledge about the properties and laboratory method for obtaining ammonia, with ...

Gas begins to evolve in the test tube. T, H 2 SO 4 ( Zhsch) C2H5OH C2H4T+H20. Concentrated sulfuric acid takes water from alcohol and ethylene is formed as a result. 2. When C2H4 is passed through bromine water, the latter becomes colorless. C2H4+Br2(aq) => C2H4Br2.

Ethylene is oxidized by bromine water at the double bond. 3. acidified permanganate also oxidizes ethylene. 5C2H4+12KMnO4+18H2SO4=10CO2+6K2SO4+12MnSO4+28H2O. The KMP04 solution becomes colorless.

>4. Let's set fire to the escaping gas. It burns with a bright luminous flame T C2H4 + 302 => 2C02 + 2H20. Practical work №11. Experimental problems by recognition And getting substances 1. We need to identify three substances: glycerol (polyhydric alcohol), aldehyde, glucose (carbohydrate). One of characteristic reactions for these substances is interaction with Cu(OH)2. First we get copper (II) hydroxide.

To do this, add a little NaOH solution to copper sulfate. CuS04+2NaOH => Cu(OH)2-i+Na2S04. A blue precipitate of hydroxide precipitates. 1) Add a little aldehyde to the precipitate formed and heat the mixture. R-0 R-O^f +2CuOH^+H20.

H OH Aldehyde blue Yellow 2CuOH => Cu20-i+H20 Yellow red As a result, a red precipitate of Cu20 is formed. 2) Now add glycerin drop by drop to Cu(OH)2 and shake the mixture. The precipitate dissolves, a bright solution is obtained. of blue color. A stable complex of glycerol with copper is formed.

CH-OH CH2-OH^ ^-O-CH2 2CH-OH + Cu(OH)2^ CH-0- """ Cl4) H-CH + 2H20 CH ° n CH2-on-CH2 3) Glucose in its chemical properties is an aldehyde alcohol, i.e., it exhibits the properties of both aldehydes and polyhydric alcohols. As an aldehyde, it enters into reactions characteristic of this class of substances, in particular, when heated, it interacts with Cu (OH) 2 to form a red-brown precipitate Cu20.

As a polyhydric alcohol, glucose gives a bright blue solution when a fresh precipitate of Cu(OH)2 is added to it.

"W+2H20+2CuOH4 r0

2CuOH => Cu20-i+H20. A red precipitate of Cu20 precipitates. 4) To determine these three substances from each test tube, add a little Cu(OH)2. In two test tubes, a bright blue solution (glucose and glycerol) is formed. Now let's heat all three mixtures: a red precipitate (aldehyde and glucose) will fall out in two test tubes. Thus, we will find out which substance is in which test tube. 2. Engine oil consists mainly of saturated hydrocarbons, and vegetable oil consists of fats formed by unsaturated acids. Vegetable oil discolors bromine water, but machine water does not. 3. a) To receive ether Let's carry out the reaction of dehydration of ethyl alcohol. T, H 2 SO 4 (zhshts) 2C2H5OH\u003e C2H5 O C2H5 + H20. The forming ether is called diethyl. This reaction takes place only under certain conditions: heating, in the presence of H2SO4, and with an excess of alcohol. B) To obtain an aldehyde from alcohol, you need to use a weak oxidizing agent, for example, Cu2+. C2H5OH+CuO => Cu+CH3C^ +H20; CH3-C- acetaldehyde C) Further oxidation of the aldehyde produces an acid. CH3~C^ +2Cu(OH)2 => CH3COOH+Cu20-+2H20; H Acetic acid is formed. 4. Sugar is complex organic matter, containing Enough a large number of carbon. To prove this, Let's take a little sugar and add H2S04(KOHi,.) to it - Sugar under the action of concentrated sulfuric acid will give up Water and turn into carbon. H 2 SO 4 ( Zhsch)С12Н22О1112С+11Н20. Concentrated H2S04 takes water from sugar, resulting in free carbon ( black matter). 5. a) For the determination of starch, there is a good qualitative reaction with iodine.

A stable complex of bright blue color is formed. Put a few drops of iodine solution on potatoes and white bread. If a blue spot forms on the products, then they contain starch. B) To test an apple for glucose content, prepare a few drops of apple juice. Let's add a little blue precipitate of Cu(OH)2. If the test solution contains glucose, then first we will get a blue soluble glucose complex, which, when heated, will decompose to red Cu20. 6.

a) First, we define starch by adding a solution of iodine to each of the three substances. In a test tube with starch, a blue complex is formed. Glucose can be distinguished from sucrose by its aldehyde properties. Both substances have the properties of a polyhydric alcohol, but only glucose also has the properties of an aldehyde. Add Cu(OH)2 to both test tubes, a blue solution is formed. But only when heated with glucose, a red precipitate Cu20 precipitates (i.e.,

aldehyde group is oxidized). B) First, let's define starch with iodine. A blue complex is formed. Now let's check the acidity of the solutions of soap and glycerin. Glycerin is slightly acidic, while soap is alkaline.

Glycerin also forms a blue solution with Cu(OH)2 (property of polyhydric alcohols). 6. Let's heat the resulting solutions. A white precipitate appears in one of the test tubes - protein denaturation occurs. Nothing happens to glycerin when heated.

Practical work No. 1

Obtaining ethylene and studying its properties

Repeat safety precautions when doing practical work!(sign in the notebook on TB)

Objective: learn how to obtain ethylene in the laboratory and conduct qualitative reactions to unsaturated hydrocarbons of the ethylene series.

Progress:

1. Pour 2-3 ml of ethyl alcohol into a test tube and carefully add 6-9 ml of concentrated sulfuric acid. Then pour in some calcined sand (sand or small pieces of pumice stone are introduced in order to prevent the liquid from jolts during boiling). Close the test tube with a stopper with a gas outlet tube, fix it in a rack and carefully heat the contents of the test tube (Fig. 7, page 44). What are you observing?

2. Pour 2-3 ml of bromine water into another test tube, lower the gas outlet tube to the bottom of this test tube and pass the evolved gas through the bromine water. What are you observing?

3. Pour 2-3 ml of a diluted potassium permanganate solution into the third test tube, and pass gas through it. What do you observe while doing this?

4. After removing the gas outlet tube from the solution and turning it with the hole up, set fire to the gas that is released. What kind of flame does ethylene burn? Why?

5. Extinguish the spirit lamp - the release of gas will gradually stop.

Formulation of completed work:

Write down the equations of the chemical reactions performed.

Conclusion:

When ethylene reacts with bromine water, the red-brown solution of bromine water becomes colorless. This reaction is quality for a double bond.

When ethylene is oxidized aqueous solution potassium permanganate produces ethylene glycol. It is noticeable that the violet color of the solution disappears. The reaction is quality for a double bond.

Unlike methane, ethylene burns with a luminous flame, which is due to the increased carbon content.

Exercise:

A mixture of ethane and ethylene with a volume of 0.8 l (n.o.) discolored 200 g of bromine water with mass fraction 1.6%. Determine the volume fraction of each gas in the mixture.