Grosse chemistry for the curious. E-library
Grosse E., Weissmantel X.
Chemistry for the Curious. Fundamentals of chemistry and entertaining experiments.
Erich Grosse, Christian Weissmantel
Chemie selbst erlebt. Das kannst auch du das chemie-experimentierbuch
2nd Russian ed. - L .: Chemistry, 1985-Leipzig, 1974.
Translated from German by L. N. Isaeva, ed. R. B. Dobrotina (ch. 1-3) and A. B. Tomchin (ch. 4-8)
© Urania-Verlag Leipzig-Jena-Berlin. Verlag für popularwissenchaftliche Literatur. Leipzig, 1968
© Translation into Russian, Publishing house "Chemistry", 1978
OCR and Spellcheck Afanasiev Vladimir and [email protected]
The book presents the basics of inorganic and organic chemistry in a popular and entertaining way. The experiments described in it, which can be done in a chemistry circle and even at home, will help to actively master the material, awaken interest in chemistry. The originality of the book lies in the fact that it is available for independent study, and the choice of experiments is determined not so much by their external effect, but by cognition.
The purpose of the book is to captivate the young reader with chemistry, to prepare him for practical work in the laboratory or in the factory.
FROM THE PUBLISHING HOUSE
When we published the first Russian edition of this book in 1978, we experienced some anxiety - after all, the book is intended for German schoolchildren, it often mentions industrial enterprises GDR, examples from life and life are given that are close to a young citizen of this country ... Will these details obscure the main content of the book? But the lively reader's interest, which manifested itself both in letters and in discussions, and most importantly, in the speed with which Chemistry for the Curious disappeared from the book shelves, convinced us of the opposite.
Over the years, the first readers have become adults, and the books, of course, have worn out. And now we are pleased to offer the second (mass) edition to the new generation of readers.
Not only to captivate the young reader with science, not only to instill in him the practical skills necessary for working in a laboratory or in production, but also to help him seriously, in an adult way, decide whether he wants and can connect his fate with chemistry - that is the goal of this books.
As for some details of life, organization of production, etc. specific to this country, they in themselves are of considerable cognitive value.
I WANT TO BECOME A CHEMIST
- I want to become a chemist! - this is how the high school student Justus Liebig (he was born in 1803) answered the question of the director of the Darmstadt gymnasium about choosing a future profession. This aroused the laughter of the teachers and schoolchildren present at the conversation. The fact is that at the beginning of the last century in Germany, and in most other countries, such a profession was not taken seriously. Chemistry was considered as an applied part of natural science, and although theoretical ideas about substances were developed, the experiment was most often not given due importance.
But Liebig, while still at the gymnasium, was engaged in experimental chemistry. Passion for chemical experiments helped him in the future research work. Already at the age of 21, Liebig became a professor at Giessen and organized a one-of-a-kind chemistry school that attracted young adherents of this science from different countries. It served as a prototype of modern special educational institutions. The innovation of teaching was, in fact, that students paid much attention to experiments. It was only thanks to Liebig that the center of gravity of the chemistry course was transferred from the classroom to the laboratory.
Nowadays, the desire to become a chemist does not make anyone laugh, on the contrary, the chemical industry is constantly in need of people who combine extensive knowledge and experimental skills with a love of chemistry.
This book should help young chemists to delve deeper into contemporary issues chemistry.
The experiments considered here are borrowed for the most part from practice. We will try to reproduce the complex processes of chemical technology using simple auxiliary tools.
Anyone who has ever been to a chemical plant, seen huge apparatuses, high-pressure boilers, electric and flame furnaces, a network of pipelines there - all this makes up the face of modern chemical production. But any chemical-technological process begins in the laboratory. Several test tubes, glass tubes and flasks are often the first functioning model of a modern process plant. Of course, a modern researcher also needs complex and expensive instruments: analytical balances, special ovens, thermostats, autoclaves, spectrographs, and electron microscopes. But when the experimental chemist enters into unknown territory, he cannot rely only on instruments and
apparatus, he must improvise and, using simple equipment, set up more and more new experiments. Only he who can assemble working installations, who will work with unremitting perseverance on every experiment and overcome the failures that await every experimenter, will become a good chemist.
The experiments described here do not use dangerous poisons and explosives, but this does not mean that the preparations recommended in the book are completely harmless. In chemistry, such indispensable reagents are constantly used, such as, for example, certain acids and alkalis. Before proceeding with the experiments, it is necessary to carefully study the last chapter, which comments on the use of individual preparations and devices. Of course, guided by the book, many experiments can be carried out, but it is much more important to thoroughly prepare, carefully assemble the equipment and carefully observe the progress of the process.
Preliminary preparations, a sketch of the equipment, all observations and results of the experiment - all this must be recorded in the protocol.
I would like to object in advance to those parents who believe that chemical experiments are a frivolous game with health. To avoid danger, you must follow all these precautions and do not experiment with hazardous substances at your own risk. Frivolity is unacceptable in any case - whether it refers to chemical experiments, behavior on the street or sports.
We hope that our reader will first of all thoroughly study the school course in chemistry, and also read special literature (a list of recommendations is given at the end of the book). The purpose of this book is to complement the basic systematized representations. Experiments are necessary for practical consolidation and creative development theoretical knowledge.
The proposed experiments cover various areas of chemistry. Therefore, our book is useful not only for future chemists, but also for those who will become builders, metallurgists, agronomists, textile workers ... The role of chemistry in various areas technology and Agriculture increases all the time - this is the chemicalization of the national economy. Without numerous chemicals and materials it would be impossible to increase the power of mechanisms and Vehicle, expand the production of consumer goods and increase labor productivity. The chemical and pharmaceutical industry produces a variety of medicines that improve health and prolong human life.
Right now in chemical industry GDR at such plants as, for example, Leuna, Schwedt,
Schkopau, Bitterfeld, Wolfen, Guben and others, more than three hundred thousand people are employed.
For the further development of the chemical industry, integration within the framework of the socialist community is very useful (for example, oil from the USSR comes via an oil pipeline to the GDR, Poland and Czechoslovakia). In accordance with the comprehensive program of socialist economic integration, many gigantic chemical enterprises have already been built, for example, a huge pulp mill in Eastern
Siberia, installation for the production of high-density polyethylene, etc.
Skilled workers, engineers and scientists are needed to improve the well-being and better meet the needs of the working people. And surely many of our young readers will take part in the implementation of this program.
1. WATER AND AIR ARE THE CHEAPEST RAW MATERIAL
WATER SUBSTANCE #1
Water is found almost everywhere on Earth, 70% of the earth's surface is occupied by the oceans; more than 1.5 trillion tons of water are contained in this giant reservoir. Under the influence of solar heat, part of the sea water constantly evaporates, and the resulting water vapor rises into the air. If the air containing water vapor is cooled, tiny water droplets will be released. Clouds are made up of such droplets, which are carried by wind currents from the sea to the continent. Under certain conditions, small droplets merge into larger ones, and rain, snow or hail falls on the Earth. The soil absorbs this precipitation and collects it in groundwater. Excess water breaks out of the soil in the form of springs, streams flow from them, merging into small and large rivers. And the rivers carry water back to the sea, and this is how the water cycle in nature ends.
Without the water cycle, the Earth would look very different. The modern structure of mountains and valleys, sea coasts and areas remote from the sea - all this arose under the influence of the mechanical and chemical effects of water.
Without water, there would be no life on Earth. All living things need water, which is at the same time the most important integral part plants and animals. Our body is approximately 65% water; in some jellyfish, its content even reaches 99%. If water suddenly disappeared from the surface of the Earth, it would turn into a dead desert.
EXPERIMENTS WITH WATER
Anyone who has ever studied at least a few hours of chemistry knows that water is
THIS IS X
chemical compound. And her chemical formula- H
2
Oh, well known to everyone. Water
consists of two elements - hydrogen and oxygen. But we still want to experiment! Let's try to decompose the "water" compound into its component parts and then create it again. We warn you: this problem is not easy to solve, water is a very stable compound. To separate a hydrogen atom from an oxygen atom, very strong auxiliaries are needed, and, on the contrary, hydrogen combines with oxygen easily and extremely violently. In this case, the adage (usually incorrect) is justified: chemistry is where something sparkles and rumbles.
Let's decompose the water
Pour iron powder into a test tube made of refractory glass (metal powder is commercially available, you can also take very thin metal filings) with a layer of 2-3 cm. Then add 0.5 ml of water drop by drop. Iron powder absorbs water. Pour about a three-centimeter layer of dry iron powder onto the wet mixture. We close the test tube with a rubber stopper, through which we pass a curved glass tube with an internal section of 3-6 mm. We protect the inside of the cork from strong heating with a piece of asbestos sheet, asbestos or glass wool. Then, at an angle, fix the test tube on a tripod or in a test tube holder, as shown in the figure. We immerse the gas outlet tube in water and fix an inverted test tube filled with water over its end. Such a device for trapping gases is called a pneumatic bath.
For the success of the experiment, it is necessary that the iron powder, starting from the dry end of the column, be heated as much as possible. This requires a strong Bunsen burner. If the gas pressure is not too low, let's increase the air supply as much as possible, so that the flame is divided into an inner cone and a "non-luminous" outer part. However, the flame should not be allowed to flash through (a weak whistle testifies to it), since in this case combustion begins already inside the burner and it heats up very much. It is necessary to immediately extinguish the burner by closing the gas supply, and then re-ignite it, having previously limited the air supply.
Let us place the burner under the test tube in such a way that the hottest outer edge of the non-luminous flame flows around the test tube. First, we will heat the area slightly above the dry column of iron powder until the test tube noticeably glows. Then slowly bring the flame under the zone of dry iron powder.
The wet layer heats up, the water evaporates, and the water vapor interacts with the hot iron powder. In this case, iron captures the oxygen of water, and hydrogen is released. It passes through a glass tube, and bubbles are formed in the catching device, which are collected in a test tube filled with water. This happens so quickly that we have time to fill the second test tube. Each filling test tube directly under water must be closed with a stopper and only then removed from the pneumatic bath.
If the gas bubbles stop forming, stop heating and set fire to the formed hydrogen. To do this, turn the test tube upside down, open it and bring the flame from below into the hole. The gas will burn quickly. We will see blue flames and hear a whistling sound, and maybe a big bang. If it popped, it means that the test tube is not pure hydrogen, but mixed with air. Air can get in when it is expelled from the equipment at the beginning of the experiment, or when using low-quality test tubes. Just in case, in order not to injure yourself with fragments during a possible explosion, before setting fire to the gas, we wrap the test tube with a wet handkerchief.
Iron easily combines with oxygen, so it can displace hydrogen from water. At room temperature, this process proceeds very slowly, on the contrary, at a temperature of red heat
- stormy. Hydrogen burns when ignited. It combines with the oxygen in the air to form water again. If hydrogen is not mixed with oxygen or air from the very beginning, combustion proceeds smoothly. A mixture of hydrogen with air or pure oxygen explodes. Such a mixture is called explosive gas, and the test in a test tube described above is a test for explosive gas. If we are working with hydrogen, then before the experiment it is necessary to make sure with the help of this sample that the hydrogen does not contain air.
Based on our first experience, we can give a general recipe for the decomposition of a chemical compound: in order to free the component A from the compound AB, you need to react with it a substance C, which combines with B more easily than A. Iron is more likely to form a compound with oxygen, than hydrogen, and therefore displaces it from the water. Other metals are also capable of this, such as zinc, aluminium, magnesium or sodium. Such metals are called active, while inactive metals: copper, silver,
gold and platinum cannot decompose water (All of the above applies to certain conditions.
Indeed, at ordinary temperatures, iron does not combine with water, at least as quickly as it happens in the experiment described. At the same time, even liquid water interacts with sodium without heating.
The specified series of metals can be quite rigorously compiled if the conditions are sufficiently clearly defined.
It is in this way that the stress series is constructed, which will be discussed below. - Approx. ed. According to their ability to combine with oxygen, metals can be put in a row that starts with the most noble metal - gold, and ends with the most reactive alkali metals - sodium, potassium, etc. The tendency to combine with an element is called affinity in chemistry. Gold has a weak and sodium a very strong affinity for oxygen. Hydrogen can be displaced from water by those metals whose affinity for oxygen is greater than the affinity for hydrogen.
Magnesium is active, but under protection
Base metals such as sodium or potassium react violently with water to form bases. Magnesium can also decompose water at room temperature:
2Mg + 2H
2
O → 2Mg(OH)
2
+ H
2
However, the resulting magnesium hydroxide is very poorly soluble in water. It remains on the metal in the form of a thin film, which delays further dissolution. Due to this inhibition of the reaction, many metals do not dissolve in water. However, if a little magnesium powder is boiled in a flask for several minutes with 5 ml of water and a few drops of an alcohol solution of phenolphthalein, the liquid will turn red. A very small amount of magnesium hydroxide (less than 0.1 mg / l) is enough for the indicator to show the main reaction. This little experience gives an idea of the high sensitivity of many chemical reactions.
Now you need to detect hydrogen, which was obtained as a result of the decomposition of water by magnesium. Since decomposition practically stops in pure water due to the formation of a protective film, care must be taken that the hydroxide layers are continuously destroyed. For this we use additives. We will achieve the desired effect with very small amounts of acid or salts such as iron (III) chloride or magnesium chloride. Place in wide test tubes a few pieces of magnesium or a little magnesium powder, or a piece of a magnesium strip. We fill one of these tubes with tap water, the other with water to which very small amounts of acid or vinegar have already been added, the third with a dilute solution of iron (III) chloride or common salt. In acidified water and in salt solutions, gas bubbles form, and magnesium dissolves vigorously. If you fill a narrow tube with water and turn it upside down and immerse it in a wide test tube, you can collect the escaping gas. From acidified water we will get so much of it that we will be able to test for detonating gas.
The formation of a surface inert film is called passivation. If not for this phenomenon, chromium, aluminum and many other metals would be destroyed in a very short time by atmospheric oxygen or water vapor.
Electrolytic decomposition of water
For the decomposition of water by electric current, the Hoffmann apparatus is most often used. Anyone who does not have such an apparatus can easily build such a device himself. Take a piece of a very wide glass tube (for example, a beaker or a wide-mouthed flask without a bottom. How to remove the bottom is described in Chapter 8, and the sharp edges must be melted on the flame of a Bunsen burner). We close the opening of the tube or the neck of the bottle with a very tightly fitted rubber stopper. We drill two holes in the cork at a not too close distance from each other, into which we insert two carbon rods as electrodes. Such rods can be bought or taken from a battery for an electric flashlight. Before use, clean the carbon rods by long-term boiling in water. We will attach current leads made of insulated copper wire to the lower ends of the carbon rods. It is best to get suitable terminals from an electrician and solder the stripped ends of the wires to them. In extreme cases, wrap the rod with wire. The insulating varnish from the wire must be carefully cleaned off, and the number of turns must be sufficiently large. We connect the wires to a flashlight battery or, better, to a lead battery. If there is a variable resistance of several ohms, we will include it in the circuit. Then the electrolysis rate will be well controlled.
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Name: Chemistry for the Curious - Fundamentals of chemistry and entertaining experiments. 1985.
The book presents the basics of inorganic and organic chemistry in a popular and entertaining way. The experiments described in it, which can be done in a chemistry circle and even at home, will help to actively master the material, awaken interest in chemistry. The originality of the book lies in the fact that it is available for independent study, and the choice of experiments is determined not so much by their external effect, but by cognition.
The purpose of the book is to captivate the young reader with chemistry, to prepare him for practical work in the laboratory or at the enterprise.
Content
Chapter 1. WATER AND AIR - THE CHEAPEST RAW MATERIAL
WATER IS THE NUMBER ONE SUBSTANCE
EXPERIMENTS WITH WATER
Let's decompose the water
Magnesium - active, but under protection
Electrolytic decomposition of water
Experiment with gases
WATER IN CRYSTALS
Finding crystallization water
adsorbed water
AIR IS AN INEXHAUSTABLE RAW MATERIAL
INTERESTING MIX
EXPERIMENTS WITH OXYGEN
Obtaining oxygen in simple ways
Let's burn the iron
Atomic oxygen
LEINA WOULD SUFFER WITHOUT NITROGEN
EXPERIMENTS WITH AMMONIA AND NITRIC ACID
ammonia fountain
Get nitric acid
NOT ALL ICE FROM WATER
Get carbon dioxide
Experiments with carbon dioxide
Chapter 2 SALT = BASE + ACID
ALKALI METAL CHLORIDES - RAW MATERIALS FOR OBTAINING BASES AND ACIDS
HOW ALKALI AND ACIDS ARE PRODUCED IN Bitterfeld
ELECTROCHEMICAL PLANT ON THE LABORATORY BENCH Mercury method
Diaphragm from a rotten egg
BASICS OF TITRATING
EXPERIMENTS WITH CHLORINE
Let's get chlorine
Simple experiments with chlorine
Synthesis of hydrogen chloride
HOW SODA IS MADE
Getting soda
BLOOD CHEMISTRY
SULFUR AND ITS COMPOUNDS
Dissolving sulfur
Carefully! I!
We get sulfides
Burning hydrogen sulfide
TWO METHODS FOR ONE PRODUCT
Experiments with "sulphurous acid"
chamber method
contact way
Gypsum acid
Get Xylolite
VALUABLE SILICATES
Isolation of silicic acid from liquid glass
Cement with filler gives concrete
Chapter 3 METALS ARE THE BASIS OF TECHNOLOGY
METALS AND THEIR COMPOUNDS
CLASSIFICATION OF METALS
ALKALI METALS (MAIN SUB-GROUP OF GROUP I)
Potassium and sodium detection
METALS OF SIDE GROUP I GROUP
Oxidation and reduction of copper
Detection of copper in alloys
Experiments with silver
Basic photography process
assay art
ALKALINE EARTH METALS (MAIN SUB-GROUP OF GROUP II)
Properties and detection of magnesium
Calcium detection
METALS OF SIDE GROUP II GROUP
Experiments with zinc
METALS OF THE MAIN SUB-GROUP OF GROUP III
Aluminum is the most important light metal
CARBON GROUP (MAIN SUB-GROUP OF GROUP IV)
Tin is a necessary but rare element.
NITROGEN GROUP (MAIN SUB-GROUP OF GROUP V)
METALS OF SIDE GROUP VI GROUP
Colored precipitates with chromium
Detection of molybdenum and tungsten
METALS OF THE SUB-GROUP OF GROUP VII
GROUP VIII TRANSITION METALS
Iron is the most commonly used metal
Cobalt is a magnet component
Nickel meets the most stringent requirements
ANALYTICS - A TOUCHSTONE FOR A YOUNG CHEMIST
GET METALS
WASHING AND ROASTING OF ORES
Ore enrichment
Roasting ore
STEELING COPPER AND LEAD IN A LABORATORY CRUCIBLE
Recovery of copper oxide
Lead from lead litharge
PYROLUSITE METAL
Let's get manganese
PRODUCTION OF MAGNESIUM BY ELECTROLYSIS OF THE MELT
Magnesium from carnallite
IRON AND NICKEL IN AN UNUSUAL FORM
Get Iron Dust
Nickel according to the same recipe
FROM METALLURGICAL RECIPES
lead alloys
Steel hardening
A SMALL COURSE OF ELECTROCHEMISTRY OF METALS
VOLTAGE RANGE OF METALS
Metal coatings, "trees" and "ice patterns" without current
LET'S LOOK BEYOND THE SCENE
Essence of a galvanic cell
PLATED COATINGS
Metal is deposited by current
Chapter 4. CHEMISTRY OF CARBON
LET'S LOOK INTO THE PAST
MARSH GAS
Let's get swamp gas
BASIC CONCEPTS OF ORGANIC CHEMISTRY
ETHENE - UNSATURATED HYDROCARBON
DETECTION OF ELEMENTS IN ORGANIC SUBSTANCES
Nitrogen detection
Halogen detection
Sulfur detection
COAL - COKE - RESIN - GAS
WE'LL CONSTRUCT A SEMI-COXING INSTALLATION
Dry distillation of wood
Semi-coking of brown coal
CARBIDE STILL NEEDED
Obtaining calcium carbide
Ethine research
SOME OF THE 800,000 COMPOUNDS
WINE ALCOHOL AND ITS RELATIVES
Methanol Research
Experiments with methanal
Exploring Methanic Acid
Experiments with ethanol
Obtaining ethane
Experiments with ethane
SOLVENTS IN HOUSEHOLD AND APPLIANCES
Carbon tetrachloride - non-flammable solvent
Propanone dissolves fat
And finally, ether
Benzene derivatives
Nitrobenzene from benzene
Aniline - the ancestor of dyes
Other representatives of the aromatic series
Get furfural from bran
Chapter 5 MATERIALS FOR EVERY TASTE: PLASTICS YESTERDAY, TODAY AND TOMORROW
SUBSTITUTE
GIANTS AMONG MOLECULES
RESEARCHING PLASTICS
Density determination
Melting test
Softening temperature
Pour point
combustion test
Examination of decomposition products
Chemical resistance
HOW NATURAL MATERIALS IMPROVE
IF YOU TAKE CELLULOSE, ACID AND CAMPHOR
Preparation of cellulose nitrates
Further processing of cellulose dinitrate
Experiments with cellulose trinitrate
WOOD AND PLASTICS
Making parchment paper
FROM SWITCH TO VEHICLE BODY
35,000 tons of phenolics per year
Let's make a transparent phenol-formaldehyde resin
Phenol-formaldehyde varnishes and adhesives
WITH FILLER YOU GET BIGGER AND... BETTER
Press material production
Laminate manufacturing
13 TIMES LIGHTER than corks
thermal insulation
Styrofoam manufacturing
Making urea-formaldehyde resin
Prepare carbamide glue
PLATES FOR BEGINNER JUGLERS
THERMOPLAST FAMILY
WE COLLECT AND DISASSEMBLE POLYSTYRENE MOLECULES
Depolymerization of polystyrene
Getting polystyrene
POLYVINYL CHLORIDE IS THE MOST IMPORTANT PLASTIC
Experiments with polyvinyl chloride
ORGANIC GLASS
CHEMISTRY CLOTHES US BETTER AND BETTER
FIBER UNDER A Magnifying Glass
Exploring fibers
SILK AND WOOL FROM WOOD
Lignin detection
Making silk Chardonnay
Production of acetate silk
Production of copper-ammonia silk
Viscose production
CHEMISTRY OPENS NEW WAYS
Chapter 6 A BRIEF ABOUT DYE CHEMISTRY
DYES FROM WOLFEN
MYSTERY OF COLOR
WE SYNTHESIZE DYES FROM ANILINE
Mauveine in vitro
Synthesizing Aniline Yellow
Aniline black - dye for cotton
GET PHTALEIN DYES
Phthalic anhydride from phthalic acid
Obtaining an indicator of phenolphthalein
What color bath water
Beautiful as the dawn
CHEMISTRY IN THE FIGHT AGAINST DISEASES
SIMPLE DISINFECTANT
Let's make a medicine
AROUND SALICYLIC ACID
Experiments with salicylic acid
FRAGRANTS, COSMETICS AND DETERGENTS
PERFUMING RETORT
Get essential oils
SCENTED ETHERS
Get esters
Preparative preparation of an ester
Fragrant alkanals from soap
Fruit essence and isovaleric acid from isoamyl alcohol
Aroma of lilac from... turpentine!
PERFUME
Let's make perfume
BEAUTY - WITH THE HELP OF CHEMISTRY
Let's do cosmetics
USEFUL FOAM
Secrets of soap making
COAL SOAP
Carry out the oxidation of paraffin
Making soap from synthetic fatty acids
How detergents work
Chapter 7 CHEMISTRY OF LIFE
FOOD AS CHEMICAL COMPOUNDS
EXPERIENCES WITH SUGAR
Is sugar on fire?
What is sugar made of
We cook artificial honey
Reactions of monosaccharides
Saccharification of potatoes and wood
Get Milk Sugar
Osaharim cotton wool
FATS - FUEL FOR THE BODY
Fat detection
Fat curing - not so easy!
PROTEIN NOT ONLY IN EGGS
How to recognize a protein?
Prepare soup concentrate
WHAT TURNS INTO WHAT?
METABOLISM
Detection of hemin using the Teichmann reaction
Blood detection using benzidine
The action of bile
"artificial stomach"
Detection of cholesterol in egg yolk
CHEMICAL PLANT IN PLANTS
Separation of green leaf dye by adsorption column chromatography
Separation of dyes from plants by paper chromatography
Starch in leaves and in margarine
Detection of starch in margarine
Detection of starch in lilac leaf
AGRONOMIST AS A CHEMIST
FOLLOWING LIBICH
ANALYSIS OF MINERAL FERTILIZERS
Cation detection
Anion detection
CHEMISTRY HELPS AGRICULTURE
Let's make an insecticide
Chapter 8 ARSENAL OF YOUNG CHEMIST
WHAT DO WE NEED?
WORKPLACE
How to equip a laboratory table
What you should always have on hand
SIMPLE LABORATORY EQUIPMENT
Plain glassware
China
measuring utensils
Burners, electric stoves and accessories
Glass container
Accessories
Chemical glassware for special purposes
Instruments for experiments in electrochemistry
Experiments with an electric arc
GLASS PROCESSING
Burner
Tube cutting
Tube bending
Tube stretching
Additional Tips
BASIC CHEMICAL REAGENTS
MAIN INORGANIC ACIDS
THE MOST IMPORTANT FOUNDATIONS.
Potassium and sodium detection.
We will keep magnesia sticks in the non-luminous flame of a Bunsen burner until the initial color of the flame disappears. Then we put a little table salt on the stick and again place it in the flame, which will turn bright yellow. Since the color is very intense, and sodium is an almost indispensable impurity in salts, one should always make sure, by comparing the color of the flame obtained with the color of the flame of a pure sodium compound, whether the element is in the form of an impurity or in the form of a main component.
Potassium colors the flame red-violet. To get rid of the interfering yellow color, in which the sodium present immediately colors the flame, we use a blue filter (cobalt glass). In this way, the potassium content of some salts can be checked.
In the presence of a small amount of lithium salts, one can observe the coloring of this element of the flame in a wonderful red color.
Grosse E., Weissmantel X.
Chemistry for the Curious. Fundamentals of chemistry and entertaining experiments.
Erich Grosse, Christian Weissmantel
Chemie selbst erlebt. Das kannst auch du das chemie-experimentierbuch 2nd Russian ed. - L.: Chemistry, 1985-
Leipzig, 1974.
Translated from German by L. N. Isaeva, ed. R. B. Dobrotina (ch. 1-3) and A. B. Tomchin (ch. 4-8)
(c) Urania-Verlag Leipzig-Jena-Berlin. Verlag für popularwissenchaftliche Literatur. Leipzig, 1968
(c) Translation into Russian, Publishing house "Chemistry", 1978 OCR and Spellcheck Afanasiev Vladimir and [email protected]
IN book in a popular and fascinating way outlines the basics of inorganic and organic chemistry. The experiments described in it, which can be done in a chemistry circle and even at home, will help to actively master the material, awaken interest in chemistry. The originality of the book lies in the fact that it is available for independent study, and the choice of experiments is determined not so much by their external effect, but by cognition.
The purpose of the book is to captivate the young reader with chemistry, to prepare him for practical work in the laboratory or at the enterprise.
FROM THE PUBLISHING HOUSE When releasing the first Russian edition of this book in 1978, we experienced some anxiety -
after all, the book is intended for German schoolchildren, it often mentions the industrial enterprises of the GDR, gives examples from life and life that are close to a young citizen of this country ... Will these details obscure the main content of the book? But the lively reader's interest, which manifested itself both in letters and in discussions, and most importantly, in the speed with which "Chemistry for the Curious" disappeared from the book shelves, convinced us of the opposite.
Over the years, the first readers have become adults, and the books, of course, have worn out. And now we are pleased to offer the second (mass) edition to the new generation of readers.
Not only to captivate the young reader with science, not only to instill in him the practical skills necessary for working in a laboratory or in production, but also to help him seriously, in an adult way, decide whether he wants and can connect his fate with chemistry - that is the goal of this books.
As for the details economic geography GDR, some details of life specific to this country, the organization of production, etc., then they in themselves are of considerable cognitive value.
I WANT TO BECOME A CHEMIST - I want to become a chemist! - this is how the high school student Justus Liebig (he was born in 1803) answered the question
Director of the Darmstadt Gymnasium on the choice of a future profession. This aroused the laughter of the teachers and schoolchildren present at the conversation. The fact is that at the beginning of the last century in Germany, and in most other countries, such a profession was not taken seriously. Chemistry was considered as an applied part of natural science, and although theoretical ideas about substances were developed, the experiment was most often not given due importance.
But Liebig, while still at the gymnasium, was engaged in experimental chemistry. Passion for chemical experiments helped him in his further research work. Already at the age of 21, Liebig became a professor at Giessen and organized a one-of-a-kind chemistry school that attracted young adherents of this science from different countries. It served as a prototype of modern special educational institutions. The innovation of teaching was, in fact, that students paid much attention to experiments. It was only thanks to Liebig that the center of gravity of the chemistry course was transferred from the classroom to the laboratory.
IN In our time, the desire to become a chemist will not make anyone laugh, on the contrary, the chemical industry is constantly in need of people who combine extensive knowledge and experimental skills with a love of chemistry.
This book should help young chemists to delve deeper into modern problems of chemistry. The experiments considered here are borrowed for the most part from practice. We will try to reproduce the complex processes of chemical technology using simple auxiliary tools.
Anyone who has ever been to a chemical plant, seen huge apparatuses, high-pressure boilers, electric and flame furnaces, a network of pipelines there - all this makes up the face of modern chemical production. But any chemical-technological process begins in the laboratory. Several test tubes, glass tubes and flasks are often the first functioning model of a modern process plant. Of course, a modern researcher also needs complex and expensive instruments: analytical balances, special ovens, thermostats, autoclaves, spectrographs, and electron microscopes. But when an experimental chemist enters an unknown area, he cannot rely only on instruments and apparatus, he must improvise and, using simple equipment, set up more and more new experiments. Only he who can assemble working installations, who will work with unremitting perseverance on every experiment and overcome the failures that await every experimenter, will become a good chemist.
The experiments described here do not use dangerous poisons and explosives, but this does not mean that the preparations recommended in the book are completely harmless. In chemistry, such irreplaceable reagents as, for example, certain acids and alkalis, are constantly used. Before proceeding with the experiments, it is necessary to carefully study the last chapter, which comments on the use of individual preparations and devices. Of course, guided by the book, many experiments can be carried out, but it is much more important to thoroughly prepare, carefully assemble the equipment and carefully observe the progress of the process. Preliminary preparations, a sketch of the equipment, all observations and results of the experiment - all this must be recorded in the protocol.
I would like to object in advance to those parents who believe that chemical experiments are a frivolous game with health. To avoid danger, you must follow all these precautions and do not experiment with hazardous substances at your own risk. Frivolity is unacceptable in any case - whether it refers to chemical experiments, behavior on the street or sports.
We hope that our reader will first of all thoroughly study the school course in chemistry, and also read special literature (a list of recommendations is given at the end of the book). The purpose of this book is to complement the basic systematized representations. Experiments are necessary for the practical consolidation and creative development of theoretical knowledge.
The proposed experiments cover various areas of chemistry. Therefore, our book is useful not only for future chemists, but also for those who will become builders, metallurgists, agronomists, textile workers...
The role of chemistry in various fields of technology and agriculture is growing all the time - this is the chemicalization of the national economy. Without numerous chemicals and materials, it would be impossible to increase the capacity of mechanisms and vehicles, expand the production of consumer goods and increase labor productivity. The chemical-pharmaceutical industry produces a variety of medicines that improve health and prolong human life.
More than 300,000 people are now employed in the chemical industry of the GDR at such combines as, for example, Leuna, Schwedt, Schkopau, Bitterfeld, Wolfen, Guben and others.
For the further development of the chemical industry, integration within the framework of the socialist community is very useful (for example, oil from the USSR comes via an oil pipeline to the GDR, Poland and Czechoslovakia). In accordance with the comprehensive program of socialist economic integration, many gigantic chemical enterprises have already been built, for example, a huge pulp mill in Eastern Siberia, a plant for the production of high-density polyethylene, etc.
Skilled workers, engineers and scientists are needed to improve the well-being and better meet the needs of the working people. And surely many of our young readers will take part in the implementation of this program.
1. WATER AND AIR - THE CHEAPEST RAW MATERIAL WATER - SUBSTANCE No. 1
Water is found almost everywhere on Earth, 70% of the earth's surface is occupied by the oceans; more than 1.5 trillion tons of water are contained in this giant reservoir. Under the influence of solar heat, part of the sea water constantly evaporates, and the resulting water vapor rises into the air. If the air containing water vapor is cooled, tiny water droplets will be released. Clouds are made up of such droplets, which are carried by wind currents from the sea to the continent. Under certain conditions, small droplets merge into larger ones, and rain, snow or hail falls on the Earth. The soil absorbs this precipitation and collects it in groundwater. Excess water seeps out
soils in the form of springs, streams flow from them, merging into small and large rivers. And the rivers carry water back to the sea, and this is how the water cycle in nature ends.
Without the water cycle, the Earth would look very different. The modern structure of mountains and valleys, sea coasts and areas remote from the sea - all this arose under the influence of the mechanical and chemical effects of water.
Without water, there would be no life on Earth. All living things need water, which is also the most important component of plants and animals. Our body is approximately 65% water; in some jellyfish, its content even reaches 99%. If water suddenly disappeared from the surface of the Earth, it would turn into a dead desert.
EXPERIMENTS WITH WATER Anyone who has ever studied at least a few hours of chemistry knows that water is a chemical
compound. And its chemical formula - H2O - is well known to everyone. Water is made up of two elements - hydrogen and oxygen. But we still want to experiment! Let's try to decompose the "water" compound into its component parts and then create it again. We warn you: this problem is not easy to solve, water is a very stable compound. To separate a hydrogen atom from an oxygen atom, very strong auxiliary means are needed, and, on the contrary, hydrogen combines with oxygen easily.
And extremely violent. In this case, the adage (usually incorrect) is justified: chemistry is where something sparkles and rumbles.
Let's decompose the water
IN pour a test tube of refractory glass with iron powder (metal powder is commercially available, you can also take very thin metal filings) in a layer 2-3 cm. Then add 0.5 ml of water drop by drop. Iron powder absorbs water. Pour about a three-centimeter layer of dry iron powder onto the wet mixture. We close the test tube with a rubber stopper, through which we pass a curved glass tube with an internal section of 3-6 mm. We protect the inside of the cork from strong heating with a piece of asbestos sheet, asbestos or glass wool. Then, at an angle, fix the test tube on a tripod or in a test tube holder, as shown in the figure. We immerse the gas outlet tube in water and fix an inverted test tube filled with water over its end. Such a device for trapping gases is called a pneumatic bath.
For the success of the experiment, it is necessary that the iron powder, starting from the dry end of the column, be heated as much as possible. This requires a strong Bunsen burner. If the gas pressure is not too low, let's increase the air supply as much as possible, so that the flame is divided into an inner cone and a "non-luminous" outer part. However, the flame should not be allowed to flash through (a weak whistle testifies to it), since in this case combustion begins already inside the burner and it heats up very much. It is necessary to immediately extinguish the burner by closing the gas supply, and then re-ignite it, having previously limited the air supply.
Let us place the burner under the test tube in such a way that the hottest outer edge of the non-luminous flame flows around the test tube. First, we will heat the area slightly above the dry column of iron powder until the test tube noticeably glows. Then slowly bring the flame under the zone of dry iron powder.
The wet layer heats up, the water evaporates, and the water vapor interacts with the hot iron powder. In this case, iron captures the oxygen of water, and hydrogen is released. It passes through a glass tube, and bubbles are formed in the catching device, which are collected in a test tube filled with water. This happens so fast that we have time to fill the second test tube. Each filling test tube directly under water must be closed with a stopper and only then removed from the pneumatic bath.
If the gas bubbles stop forming, stop heating and set fire to the formed hydrogen. To do this, turn the test tube upside down, open it and bring the flame from below into the hole. The gas will burn quickly. We will see blue flames and hear a whistling sound, and maybe a big bang. If it popped, it means that the test tube is not pure hydrogen, but mixed with air. Air can get in when it is expelled from the equipment at the beginning of the experiment, or when using low-quality test tubes. Just in case, in order not to injure yourself with fragments during a possible explosion, before setting fire to the gas, we wrap the test tube with a wet handkerchief.
Iron easily combines with oxygen, so it can displace hydrogen from water. At room temperature, this process proceeds very slowly, on the contrary, at a red-hot temperature, it proceeds rapidly. Hydrogen burns when ignited. It combines with the oxygen in the air
And water is formed again. If hydrogen is not mixed from the beginning with oxygen or air, combustion
flows smoothly. A mixture of hydrogen with air or pure oxygen explodes. Such a mixture is called explosive gas, and the test in a test tube described above is a test for explosive gas. If we are working with hydrogen, then before the experiment it is necessary to make sure with the help of this sample that the hydrogen does not contain air.
Based on our first experience, we can give a general recipe for the decomposition of a chemical compound: in order to free the component A from the compound AB, you need to react with it a substance C, which combines with B more easily than A. Iron is more likely to form a compound with oxygen, than hydrogen, and therefore displaces it from the water. Other metals are also capable of this, such as zinc, aluminium, magnesium or sodium. Such metals are called active, while inactive metals: copper, silver, gold and platinum cannot decompose water (All of the above applies to certain conditions. Indeed, at ordinary temperatures, iron does not combine with water, at least not so quickly, as it happens in the experiment described. At the same time, even liquid water interacts with sodium without heating. The indicated series of metals can be quite strictly compiled if the conditions are sufficiently clearly defined. It is in this way that the voltage series, which will be discussed below, is constructed. - Note ed Metals by their ability to combine with oxygen can be put in a row that starts with the most noble metal - gold, and ends with the most reactive alkali metals - sodium, potassium, etc. The tendency to combine with an element is called affinity in chemistry. Gold has a weak, and sodium - a very strong affinity for oxygen.Metals whose affinity for acids can displace hydrogen from water. more than the affinity of hydrogen for it.
Magnesium is active but protected Base metals such as sodium or potassium react violently with water to form
grounds. Magnesium can also decompose water already at room temperature: 2Mg + 2H2O? 2Mg(OH)2 + H2
However, the resulting magnesium hydroxide is very poorly soluble in water. It remains on the metal in the form of a thin film, which delays further dissolution. Due to this inhibition of the reaction, many metals do not dissolve in water. However, if a little magnesium powder is boiled in a flask for several minutes with 5 ml of water and a few drops of an alcohol solution of phenolphthalein, the liquid will turn red. A very small amount of magnesium hydroxide (less than 0.1 mg / l) is enough for the indicator to show the main reaction. This little experience gives an idea of the high sensitivity of many chemical reactions.
Now you need to detect hydrogen, which was obtained as a result of the decomposition of water by magnesium. Since decomposition practically stops in pure water due to the formation of a protective film, care must be taken that the hydroxide layers are continuously destroyed. For this we use additives. We will achieve the desired effect with very small amounts of acid or salts such as iron (III) chloride or magnesium chloride. Place in wide test tubes a few pieces of magnesium or a little magnesium powder, or a piece of a magnesium strip. We fill one of these tubes with tap water, the other with water to which very small amounts of acid or vinegar have already been added, the third with a dilute solution of iron (III) chloride or common salt. In acidified water and in salt solutions, gas bubbles form, and magnesium dissolves vigorously. If you fill a narrow tube with water and turn it upside down and immerse it in a wide test tube, you can collect the escaping gas. From acidified water we will get so much of it that we will be able to test for detonating gas.
The formation of a surface inert film is called passivation. If not for this phenomenon, chromium, aluminum and many other metals would be destroyed in a very short time by atmospheric oxygen or water vapor.
Electrolytic decomposition of water For the decomposition of water by electric current, the Hoffmann apparatus is most often used. Who is not
has such an apparatus, he can easily build such a device. Take a piece of a very wide glass tube (for example, a beaker or a wide-mouthed flask without a bottom. How to remove the bottom is described in Chapter 8, and the sharp edges must be melted on the flame of a Bunsen burner). We close the opening of the tube or the neck of the bottle with a very tightly fitted rubber stopper. We drill two holes in the cork at a not too close distance from each other, into which we insert two carbon rods as electrodes. Such rods can be bought or taken from a battery for an electric flashlight. Before use, clean the carbon rods by long-term boiling in water. To the lower ends of the carbon rods we will attach current leads made of insulated
copper wire. It is best to get suitable terminals from an electrician and solder the stripped ends of the wires to them. In extreme cases, wrap the rod with wire. The insulating varnish from the wire must be carefully cleaned off, and the number of turns must be sufficiently large. We connect the wires to a flashlight battery or, better, to a lead battery. If there is a variable resistance of several ohms, we will include it in the circuit. Then the electrolysis rate will be well controlled.
Let us fill the prepared electrolysis vessel about two-thirds with water, to which we add a little dilute sulfuric acid. Pure water conducts electricity very poorly. Already a small amount of acid greatly increases the conductivity. It is best that the concentration of sulfuric acid is 2-4%. Be careful - even dilute sulfuric acid corrodes the skin. Remember forever: when diluting acid, it should be poured very slowly into water; in no case should you do the opposite - pour water into acid.
The cell is ready. Now let's close the circuit. Gas is released on both electrodes: on the positive pole (anode) it is weaker, on the negative (cathode) it is stronger. Let's collect gases for their study. To do this, we place inverted test tubes filled with water over the electrodes - only so that they do not stand on a rubber stopper, otherwise the electrical circuit will be interrupted.
IN gas will collect in both tubes. Ideally, one would expect exactly half as much gas to form at the anode as at the cathode. After all, oxygen is released at the anode, and hydrogen is released at the cathode. Since the formula of water is H2O, there are two hydrogen atoms per oxygen atom, and the decomposition of water should form twice as many hydrogen atoms as oxygen. On the other hand, we know from the school course that equal volumes of gases always contain an even number of molecules (Avogadro's law), and both a hydrogen molecule and an oxygen molecule contain two element atoms.
Despite the correctness of this theory, we will be somewhat disappointed when we compare the obtained volumes of gases. There will be little oxygen, since part of it will combine with the carbon of the electrode. For accurate studies, it is necessary to use electrodes made of a noble metal (preferably platinum).
Let's experiment with gases. If a sufficiently powerful current source (for example, a battery) is used during electrolysis, then
considerable quantities of both gases can be obtained and simple experiments can be carried out with them.
IN in a test tube filled with hydrogen, we will carry out a test for detonating gas. In general, it gives a negative result, and the resulting pure hydrogen burns quietly. True, a positive reaction can also be obtained - if hydrogen is mixed with oxygen dissolved in the water of the pneumatic bath. This can happen when the tubes are inserted carelessly or, more often, when the electrodes are close together. Oxygen is easy to detect with a smoldering torch. We light a wooden splinter, let it burn for some time in the air, then extinguish the flame by quickly blowing on it. Let us introduce the smoldering, charred end of the torch into a test tube with oxygen. We will see how the smoldering torch ignites. We will continue research as long as there is gas in the test tubes. With our electrolysis device, we can also obtain pure oxyhydrogen gas and blow it up. To do this, we place a thick-walled glass filled with water simultaneously over both electrodes. During electrolysis, it will collect a mixture of oxygen and hydrogen. As soon as the glass begins to fill, carefully bring it close, hole down, to the flame of the Bunsen burner. A strong pop will follow and the walls of the vessel will be moistened. From the individual elements, as a result of the combination reaction, we received water.
Only to conduct this experiment must be sure to wear protective glasses! In order to avoid an accident, before the experiment, you need to be instructed by knowledgeable specialist. In addition, it is possible to obtain a gas mixture only in a small amount, using, as a last resort, a glass with a capacity of not more than 250 ml. We wrap the glass with a damp dense cloth (preferably with a towel) so as not to get hurt if it breaks. And one more thing: before setting fire to the mixture, as a precaution, we will open our mouth to protect the eardrums. Note also that electrolytic production of hydrogen is often accompanied by explosions. This explosive gas ignites spontaneously under the action of an electric spark or catalytically acting impurities. For this reason, only small quantities of gas can be obtained and a sufficient distance can be kept during the experiment.
WATER IN CRYSTALS Chemicals are considered especially pure if they are homogeneous, large enough
And well-formed crystals. Polluted substances do not form crystals at all or they are small and irregular in shape. Of course, this does not mean that every non-crystalline
substance is contaminated. And just the largest and most beautiful crystals often contain water of crystallization, which is bound in the crystal and can only be removed with great difficulty; while the crystals are destroyed. Crystallization water is not classified by chemists as a contaminant of a chemical compound. In all experiments, however, if we want to obtain quantitatively correct results, we must take into account the presence of water of crystallization in solids. For example, blue crystals blue vitriol[copper (II) sulfate] contain up to 30% water, and the so-called soda ash (sodium carbonate) - even 60%. Consequently: 100 g of crystalline copper sulfate contains only 64 g of anhydrous salt, and buying 1 kg of soda ash, we get twice as much water as soda.
We detect crystallization water. We add some salt (on the tip of a knife) into a heat-resistant well-dried test tube and
let us heat it at first weakly, and then more strongly on the flame of a Bunsen burner. Take, for example, copper sulfate, sodium carbonate, magnesium chloride, sodium chloride (table salt) and other salts. In most cases, the crystals will crack and droplets of water will appear in the cold upper part of the tube. Of these salts, only pure salt does not contain water of crystallization. After heating copper sulfate, a white precipitate of anhydrous salt remains, the blue color disappears completely with the departure of crystallization water. Cobalt salts, adding water of crystallization, change color from blue to red. We can do this with a few crystals of cobalt (II) chloride - first heat the salt in a test tube, and then place it in humid air.
Adsorbed water In a water molecule, the bonds going from the center of the oxygen atom to both hydrogen atoms form an angle of about 104±.
As is known, atoms in compounds tend to form filled electron shells. In our case (with water), this means that both hydrogen bond electrons are attracted to oxygen, which is more electronegative. But here we are not talking about complete ionization, but about a shift in the center of gravity of the charge, when a compound of a partially ionic nature is formed. As a result, water molecules acquire the properties of an electric dipole with a negative end on the oxygen atom, and a positive end on the hydrogen atoms. This feature is of great practical importance, since many of the unusual properties of water compared to other liquids are due to the nature of the dipole. Thus, water molecules easily form a tetrahedral structure. This ordering, which increases below 4 ± C, explains why water has a minimum density at 4 ± C, and the porosity of the molecular structure of ice is about 10% greater than that of liquid water. A large external pressure does not prevent an increase in volume during freezing - drivers are convinced of this with annoyance, looking at a defrosted engine or radiator. Let's reproduce this process: fill the medicine bottle to the brim with water, close it tightly with a screw cap and put it in the cold or in the freezer.
The connection of water molecules can be imagined as an attraction of oppositely charged ends of dipoles. The hydrogen atoms are connected to two much larger oxygen atoms by a specific ionic bond called a bridging hydrogen bond. Due to their dipole nature, water molecules are especially capable of adsorption (attachment) at interfaces. Most of the solids in humid air are only covered by a monomolecular adsorption layer of water. On glasses due to the addition of water molecules by silicates alkali metals surface films are formed in which water is quite strongly bound. Let's make sure of this. In a round-bottom flask we put a few crystals of anhydrous cobalt (II) chloride and close the flask with a piece of cotton wool. When heated on a wire mesh in the flame of a Bunsen burner to a temperature above 150 0C, a significant amount of adsorbed water will be released, which, when cooled, will be partially absorbed by cobalt (II) chloride and change its color from blue to red. The effect will be even more pronounced if we put some crushed glass or glass wool into the flask. With further heating to temperatures above 300 ± C, water is again released from the glass, so the glass parts of high-vacuum equipment are annealed to a softening temperature.
AIR IS AN INEXHAUSTABLE RAW MATERIAL Today we know very well the Earth's atmosphere, the thickness of which is more than 1000 km.
Balloons with and without people, planes and rockets rose to a great height of air
open windows (due to the resulting sulfur oxides). The resulting sodium nitrite will be saved for subsequent experiments.
The process proceeds as follows: heating
2KNO3-? 2KNO2+ О2
You can get oxygen in other ways. Potassium permanganate KMnO4 (potassium salt of manganese acid) gives off oxygen when heated and turns into manganese (IV) oxide: 4KMnO4 - 4MnO2 + 2K2O + 3O2
(It would be more correct to represent this reaction as follows: 2КМnO4 ? МnO2 + К2МnО4 + O2. Approx. ed.)
From 10 g of potassium permanganate, you can get about a liter of oxygen, so two grams is enough to fill five test tubes of normal size with oxygen. Potassium permanganate can be purchased at any pharmacy if it is not available in the home first aid kit.
We heat a certain amount of potassium permanganate in a refractory test tube and catch the released oxygen in the test tubes using a pneumatic bath. The crystals are cracked and destroyed, and often a certain amount of dusty permanganate is carried along with the gas. The water in the pneumatic bath and the outlet pipe will turn red in this case. After the end of the experiment, we clean the bath and the tube with a solution of sodium thiosulfate (hyposulfite) - a photo-fixer, which we slightly acidify with dilute hydrochloric acid.
IN large quantities oxygen can also be obtained from hydrogen peroxide H2O2. We will buy a three percent disinfectant solution or a preparation for treating wounds in a pharmacy. Hydrogen peroxide is not very stable. Already when standing in air, it decomposes into oxygen and water:
2H2O2? 2H2O + O2
Decomposition can be significantly accelerated by adding a little manganese dioxide MnO2 (pyrolusite), activated carbon, metal powder, blood (coagulated or fresh), and saliva to the peroxide. These substances act as catalysts.
We can be convinced of this if we place about 1 ml of hydrogen peroxide with one of the above substances in a small test tube, and we establish the presence of evolving oxygen using a test with a splinter. If an equal amount of animal blood is added to 5 ml of a 3% hydrogen peroxide solution in a beaker, the mixture will foam strongly, the foam will harden and swell as a result of the release of oxygen bubbles.
Then we will test the catalytic effect of a 10% solution of copper sulfate (II) with the addition of potassium hydroxide (caustic potash) and without it, a solution of iron sulfate (II), a solution of iron (III) chloride (with and without the addition of iron powder), carbonate sodium, sodium chloride and organic substances (milk, sugar, crushed leaves of green plants, etc.). Now we have seen from experience that various substances catalytically accelerate the decomposition of hydrogen peroxide.
Catalysts increase the rate of a chemical reaction without being consumed. Ultimately, they reduce the activation energy needed to excite the reaction. But there are also substances that act in the opposite way. They are called negative catalysts, anti-catalysts, stabilizers or inhibitors. For example, phosphoric acid prevents the decomposition of hydrogen peroxide. Therefore, a commercial hydrogen peroxide solution is usually stabilized with phosphoric or uric acid.
Catalysts are essential for many chemical engineering processes. But even in wildlife, so-called biocatalysts (enzymes, enzymes, hormones) are involved in many processes. Since catalysts are not consumed in reactions, they can act even in small quantities. One gram of rennet is enough to coagulate 400-800 kg of milk protein.
Of particular importance for the operation of catalysts is their surface area. To increase the surface, porous, cracked substances with a developed inner surface are used, compact substances or metals are sprayed onto so-called carriers. For example, 100 g of a supported platinum catalyst contains only about 200 mg of platinum; 1 g of compact nickel has a surface area of 0.8 cm2, while 1 g of nickel powder has a surface area of 10 m2. This corresponds to a ratio of 1: 100,000; 1 g of active alumina has a surface area of 200 to 200 m2, for 1 g of active carbon this value is even 1000 m2. In some catalyst installations - several million marks. Thus, an 18 m high gasoline contact furnace in Belen contains 9-10 tons of catalyst.
Let's burn the iron Let's use the collected oxygen for experiments on oxidation. Let's bring in oxygen-filled
test tubes are small, if possible finely ground, samples of lead, copper, aluminum, zinc and
tin and loosely close the test tubes with cotton wool. When heated, metals will burn with the appearance of a bright flame; oxides will remain in the test tubes.
IN pure oxygen will also burn a thin iron wire. Give it a spiral shape
And we will strengthen on one of the ends of a piece of wood soaked in paraffin, which we will set on fire. We will introduce the wire as soon as possible into a wide beaker filled with oxygen. To prevent the glass from cracking due to falling hot particles, it is necessary to submerge the bottom of the glass in a layer of sand or water. The wire will burn with the appearance of bright flying sparks, resulting in the formation of iron oxide (II, III), the so-called scale:
3Fe + 2O2? Fe3O4
Oxygen is a colorless, odorless and tasteless gas, partially soluble in water; 1 liter of oxygen at 0 ± C and 760 mm Hg. Art. weighs 1.429 g. Therefore, oxygen is heavier than air (1 liter of air under the same conditions weighs 1.293 g). With almost all metals and non-metals, oxygen forms oxides.
Atomic oxygen
IN Oxygen occurs naturally in the form of diatomic molecules. Atomic oxygen O has an extremely strong oxidizing power. It is obtained by the decomposition of ozone, the molecule of which contains three oxygen atoms:
If poured into a porcelain cup concentrated sulfuric acid pour a little finely atomized potassium permanganate, ozone is formed. (Put on goggles! Explosive!) We will hold over the cup: a) a piece of starch paper moistened with potassium iodide, b) a strip of litmus paper. Iodine will be released from potassium iodide, which will color the starch paper blue (starch iodine reaction); litmus paper will discolor. Finally, immerse on a glass rod in a mixture of sulfuric acid and permanganate a little cotton wool soaked in alcohol or turpentine. Cotton wool with an explosion will burn.
In high (30-45 km) layers of air, in the so-called ozonosphere, ozone occurs under the influence of ultraviolet rays or during a thunderstorm, and in technology it is most often obtained as a result of a quiet electric discharge in an ozonator. It is used for disinfection and ozonation of air in rooms (hospitals, cold stores), as well as for the disinfection of drinking water.
LEINA WOULD SUFFER WITHOUT NITROGEN If, at the beginning of our century, a geography teacher in a German gymnasium had asked his student about
Leine, he would hardly have received a satisfactory answer. At that time, Leuna was a village in the state district of Merseburg and had about three hundred inhabitants. The geographic book of 1899 says that there are deposits of brown coal, which can be used to obtain pressed peat, mountain wax (paraffin) and oil - "solar oil".
The current student will easily answer the same question of the teacher that Leuna lies on the section of the Merseburg-Grosskorbet railway track and there is the largest chemical plant republics. Leina has become famous in recent years. The history of Leina's enterprise is also part of German history. It began during the First World War and seemed destined to end during the Second.
IN 1908 head of the institute physical chemistry and electrochemistry at the technical university in Karlsruhe, Dr. Haber invited Karl Bosch as an employee, who later headed the nitrogen production department at the Baden aniline and soda factory. Together with Dr. Mittash
And engineer Lappe, from 1909 to 1912, they conducted more than 10,000 experiments in a specially equipped laboratory in order to combine air nitrogen with hydrogen in the presence of a catalyst. As a result of this reaction, ammonia is formed - the starting product for many types of explosives and artificial fertilizers. This is how the Haber-Bosch method was developed.
One of the first ammonia productions was organized at the Leuna plants by the reaction: N2 + 3H2 = 2NH3. This reaction is reversible, shifting towards the formation of NH3 only at high pressures. The implementation of the technological method for the synthesis of ammonia was the final stage of many years of work by many scientists to solve the problem of bound nitrogen. In the process of studying this reaction, in addition to a practically important result, it was possible to find out many of the most important issues related to the theory of chemical reactions (equilibrium shift under the influence of temperature and pressure, the action of a catalyst, etc.), - Note. ed.
Carl Bosch chose the site for a large ammonia synthesis plant. On May 28, 1916, the construction of an ammonia plant began in Merseburg. At this time, battles raged with unabated force on the western front. Eleven months after the first hit with a shovel, 27
April 1917, the company shipped the first tankers of ammonia, a new raw material for a deadly war.
The workers of Leuna, organizing mass strikes, waged a determined struggle against the war.
The Lane plant was continuously expanded. Ammonia was no longer the only product. Two years after the start-up, the production of ammonium sulfate began, in 1923 to receive methanol, and since 1927 - gasoline. In 1945, it seemed that the huge enterprise was dead forever - 10,000 bombs dropped during 23 raids destroyed it by 80%. Thanks to Soviet assistance, it revived again, first as an enterprise of the Soviet state joint-stock company upon receipt mineral fertilizers. In 1954, it became the property of the whole people, and since then its capacity, thanks to the rationalization and expansion of production, has steadily increased.
The plants of the plant cover an area of 4 km2. Two located 1.7 km apart railway stations More than 32,000 workers arrive daily at the Lsina North Plant and the Lönna South Plant. 13 giant chimneys, cooling towers and distillation columns, long hangars and bunkers define the silhouette of the plant.
Along with such an important raw material as brown coal, the role of oil is increasing. This important raw material is supplied to the chemical centers of the republic through the Druzhba oil pipeline, which stretches from Soviet Union through Poland in the GDR.
Thousands of tons of more than 400 basic and intermediate chemicals, from fuels to raw materials for plastics, are produced from oil, air and water. Oil refining also releases many inorganic chemicals. Ammonia and nitric acid are used to produce fertilizers and other products.
FROM On February 1, 1966, Leuna took on a special meaning. The installations of the first stage of Leina II, the first petrochemical base of the GDR, began to produce products. Approximately 2,000 operating plants have been built on an area of 200 hectares, serving 2,100 workers. Ethene, high-pressure polyethylene, caprolactam, phenol are produced here. This is where the cracking of gasoline takes place. The Lüip II plant is operating at high productivity. Each worker in this plant produces 6 times more products than his counterpart in the Leuna 1 plant.
The company has contributed tremendously to the achievement of the GDR world-class in the field of petrochemistry. EXPERIMENTS WITH AMMONIA AND NITRIC ACID According to the Haber-Bosch method from air, water vapor and brown coal (or brown coal coke) or
using the gasification of oil residues, a mixture of nitrogen and hydrogen is obtained. After purification (removal of sulfur, oxide and carbon dioxide) on a mixed catalyst at a pressure of 240 kgf/cm2 and a temperature of 420-610 ± C, the mixture is converted into ammonia:
N2+ 3H2 = 2NH3 + Q
largest economic effect gives use for the synthesis of waste from oil refining processes.
Ammonia Fountain Ammonia is a colorless gas. It irritates the respiratory tract and is toxic in high concentrations.
Ammonia is lighter than air, 1 liter of gas weighs 0.7709 g. It dissolves extremely well in water, and we will now verify this from experience.
From a commercial 25% ammonia solution (ammonium hydroxide, NH4OH, ammonia), we isolate ammonia when heated, which we collect in a dry round-bottom flask. (Never use a flat-bottomed or Erlenmeyer flask! These vessels cannot withstand a vacuum
And explode. For this experiment, it is also convenient to use the lower parts of the flasks for washing gases.) Then we close the flask with a rubber stopper, into the hole of which a glass tube is inserted at the end. Fill a large beaker with water with a few drops of phenolphthalein. Repeatedly immersing the neck of the flask in this solution, we will try to introduce a few drops of water into the flask through the tube. Due to the high solubility of ammonia (702 volumes of ammonia dissolve in 1 volume of water at 20 0C), most of the gas will dissolve. A vacuum will occur in the flask, and the external air pressure will eject with great strength water from the beaker into the flask. The red color of the indicator in the flask indicates the presence of the main medium there.
Get nitric acid
FROM using catalytic oxidation (Ostwald method), ammonia can be converted into nitric acid. At the Bitterfeld chemical plant, a mixture of ammonia and air is passed at high speed over platinum-cobalt catalyst. The resulting colorless monoxide