Katasonov Nikita, Savostyanova Evgeniya, Zadorina Elizaveta, Dmitriev Ilya, Ermakov Pavel

The research project "Chemical reactions in everyday life" was prepared by a group of students in grades 8-9 for the school conference of research works. Goals and objectives:

1. Identification of the most commonly used chemical reactions in everyday life.

2. Literature analysis to establish the essencereactions.

3. Define the degree of safety (danger) of reaction products for humans.

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Chemical reactions in our daily life Project participants: 1. Savostyanova Evgeniya Konstantinovna 9th grade 2.Zadorina Elizaveta Vadimovna 8th grade 3.Ermakov Pavel Igorevich 9th grade 4.Dmitriev Ilya Alekseevich 9th grade 5. Katasonov Nikita Sergeevich 9th grade Supervisor: Lazareva Elena Aleksandrovna 2014 Municipal budgetary educational institution "Secondary school number 17"

Relevance of the chosen topic Nowadays, millions of different substances are known. Many of them are used not only in industry and agriculture, but also in everyday life. Unfortunately, not all people have basic chemical knowledge about substances and their transformations. We believe that it is necessary to instill chemical literacy even from school. Therefore, the topic "Chemical reactions in our daily life" will be relevant.

Goals and objectives: 1. Identification of the most commonly used chemical reactions in everyday life. 2. Analysis of the literature to establish the essence of the reactions. 3. Determine the degree of safety (danger) of reaction products for humans.

Combustion of natural gas Russia is a leader in natural gas reserves and production. Therefore, in our homes we use the natural gas combustion reaction to generate heat energy. Natural gas is a mixture of gases formed in the bowels of the Earth during the anaerobic decomposition of organic substances. Chemical composition: ethane (C 2 H 6), propane (C 3 H 8) butane (C 4 H 10). And also other non-hydrocarbon substances: hydrogen (H 2), hydrogen sulfide (H 2 S), carbon dioxide (CO 2), nitrogen (N 2), helium (He). The main part of natural gas is methane (CH 4) - from 92 to 98%. It is a colorless, light, odorless, flammable gas, almost insoluble in water. A mixture of methane in air is explosive. The reaction of combustion of methane CH 4 + 2O 2 \u003d CO 2 + 2H 2 O + Q. Methane burns with a bluish or almost colorless flame, releasing a large amount of heat (879 kJ / mol). When using gas equipment in the house, it is necessary to: check the chimney, ventilate the room, monitor the condition of the gas pipelines, do not leave the working gas equipment unattended.

Match burning With a large selection of different lighters, matches are very popular. What processes take place when a match is lit? Here it was struck on the boxes. There was a flame and a sharp smell of "sulfur". The process started by friction. First, red phosphorus caught fire, which was on the matchbox 4P + 5O 2 \u003d 2P 2 O 5 Phosphorus, which gives high temperature during friction, set fire to a mixture of sulfur and berthollet salt in the match head S + O 2 \u003d SO 2 (SO 2 is a sulfur dioxide, source of pungent odor). The head set fire to wood С 6 Н 10 О 5 + 6О 2 \u003d 6СО 2 + 5Н 2 О Almost all combustion products are harmful to the body. Only when one match burns, an insignificant amount is released, which does not have a significant effect on a person. But when using matches, a chemically educated person should remember that "MATCHES ARE NOT A BIG!"

Soap hydrolysis In production and everyday life, soaps are technical mixtures of water-soluble salts of higher fatty acids, often with the addition of some other substances that have a detergent effect. The mixtures are usually based on sodium (less often potassium and ammonium) salts of saturated and unsaturated fatty acids with the number of carbon atoms in the molecule from 12 to 18 (stearic, palmitic, myristic, lauric and oleic). Salts of naphthenic and resin acids are also often referred to soaps, and sometimes other compounds that have detergency in solutions. Soaps are formed by a strong base and a weak acid, therefore they easily undergo hydrolysis: C 17 H 35 COONa + H 2 O \u003d C 17 H 35 COOH + NaOH The environment during hydrolysis is alkaline, therefore soaps are quite aggressive towards the skin and their frequent use leads to degreasing ... There are a great many varieties and brands of soaps, and before choosing the most suitable one, you need to determine the type of your skin. Oily skin is often shiny due to heavy sweat and grease separation and usually has large pores. Within 2 hours after washing, oily skin leaves spots on the napkin applied to the face. This skin requires a mildly drying soap. Dry skin is thin and very sensitive to wind and weather, and the pores on it are small and thin; it cracks easily, as it is not elastic enough. Such skin needs to create maximum comfort and gentle treatment, it is better to use expensive soaps. Normal skin is soft, smooth and has medium pores.

Hydrogen peroxide Hydrogen peroxide is the simplest representative of peroxides. Colorless liquid with a "metallic" taste, soluble in water, alcohol and ether. Ego is often used in everyday life as a bleach and antiseptic. When hydrogen peroxide decomposes (when we treat a wound), water and oxygen gas are released. 2Н 2 О 2 \u003d О 2 + 2Н 2 О At low doses, a small amount of oxygen is released, respectively. In a small volume, pure oxygen is not dangerous, but in a large volume? And in large quantities, pure oxygen is toxic and can cause pulmonary oxygen poisoning and a harmful effect on the central nervous system. The first exposure is accompanied by the following symptoms: irritation of the lung tissue. It can begin with mild irritation of the throat and subsequent coughing. In severe cases, there may be a prolonged burning sensation in the chest and an uncontrolled cough. Pulmonary oxygen toxicity can also cause decreased lung capacity and reduced gas exchange, although these complications are extremely rare. And the symptoms of the second exposure (toxic damage to the central nervous system) include: visual impairment (tunnel vision, inability to focus), hearing impairment (ringing in the ears, the appearance of extraneous sounds), nausea, convulsive contractions (especially of the muscles of the face), increased sensitivity to external stimuli and dizziness ... But all this is possible only when using large volumes of hydrogen peroxide, and the usual 3% peroxide is not capable of this.

Vinegar Quenching The vinegar quenching process is used when kneading bun and pancake dough. Baking soda, when exposed to high temperatures or acidic environments, gives an enhanced reaction to release carbon dioxide, which in turn leads to splendor and porosity. CH 3 COOH + NaHCO 3 \u003d CH 3 COONa + H 2 O + CO 2 The question "to extinguish or not to extinguish soda with vinegar when baking" is as eternal as the question "which came before - a chicken or an egg." However, after digging in the literature, breaking a bunch of sites, including foreign ones, I came to the conclusion that this issue is at most 70-80 years old. Break a great many recipes of old Russian cuisine did not find a single one where soda was mentioned. Previously, baking in our country was mainly yeast, or without the addition of any accelerators of lifting and opening at all. So, baking soda was invented by the French chemist Leblanc at the end of the 18th century. This invention reached Russia much later, after receiving a new method of its manufacture. As soon as Russian housewives had such a product as soda, they began to use and use it in cooking. Why was it decided to extinguish the soda? Yes, simply because our tradition is all "hot, hot" in this case - only harmful. Quick baking soda in hot baked goods has a very unpleasant "soapy" taste. What was "corrected" by quenching it, namely, adding boiling water or fermented milk products to the soda. For pancakes, this method still gives very good results. However, you can imagine what happens to the shortcrust pastry if you pour a glass of boiling water into it? The answer is obvious. Therefore, it was thought up to replace boiling water or fermented milk products with diluted 9% vinegar or lemon juice.

Conclusion We can observe many chemical reactions not only in chemistry lessons, but also in everyday life. These reactions are not only safe (as long as the safety rules are followed), but some of them are also useless. For example: extinguishing baking soda with vinegar, any skilled chef would say it is a waste of time. But without such reactions as hydrolysis and combustion, we simply have no idea of \u200b\u200bfurther existence. Gases are released during these chemical reactions. They are safe (in a certain amount). When using chemicals in the home, you must comply with safety regulations.

Sources of information 1. Kritsman, V.A., Stanzo, V.V. Encyclopedic Dictionary of a Young Chemist [Text] - M.: Pedagogy, 1990. 2. Lavrova, S.А. Entertaining chemistry [Text] -M. : White City, 2009. 3. Ryumin, V. Entertaining Chemistry [Text] - M .: Tsentrpoligraf, 2012. 4. Kurdyumov, G.M. 1234 questions in Chemistry [Text] - M.: Mir, Binom, 2007. 5. Guzei, LS, Kuznetsov, V.N. New reference book on chemistry [Text] -M. : Big Dipper, 1999 6. Wikipedia [Electronic resource] - Access mode: ru.wikipedia.org 7. Egorova, AS. Chemistry Tutor [Text] -M. : Phoenix, 2007 8. Chemistry and Life [Electronic resource] - Access mode: http: //www.hij.ru 9. Chemistry around us [Electronic resource] - Access mode: http://interestingchem.narod.ru/chemaround.htm

I bet you’ve seen something like Mom’s silver ring darken over time. Or how a nail rusts. Or how wooden logs burn into ash. Well, if mom doesn't like silver, and you have never gone on hikes, and you saw for sure how a tea bag is brewed in a cup.

What do all these examples have in common? And the fact that they all belong to chemical phenomena.

Chemical phenomena in everyday life

These include those that can be observed in the daily life of a modern person. Some of them are quite simple and obvious, anyone can observe them in their kitchen: for example, brewing tea. Tea leaves heated with boiling water change their properties, as a result, the composition of the water changes: it acquires a different color, taste and properties. That is, a new substance is obtained.

If sugar is poured into the same tea, a chemical reaction will result in a solution that will again possess a set of new characteristics. First of all, new, sweet, taste.

Using the example of strong (concentrated) tea brewing, you can independently carry out one more experiment: clarify the tea with the help of a lemon wedge. Through the acid contained in lemon juice, the liquid will once again change its composition.

Can you observe other phenomena in everyday life? For example, chemical phenomena include the process of combustion of fuel in the engine.

Simply put, the combustion reaction in an engine can be described as oxygen + fuel \u003d water + carbon dioxide.

In general, several reactions take place in the chamber of an internal combustion engine, involving fuel (hydrocarbons), air and an ignition spark. More precisely, not just fuel - a fuel-air mixture of hydrocarbons, oxygen, nitrogen. The mixture is compressed and heated before ignition.

The combustion of the mixture occurs in a split second, as a result, the bond between the hydrogen and carbon atoms is destroyed. Thanks to this, a large amount of energy is released, which drives the piston, and that - the crankshaft.

Subsequently, hydrogen and carbon atoms combine with oxygen atoms, water and carbon dioxide are formed.

Ideally, the reaction of complete fuel combustion should look like this: CnH2n + 2 + (1.5n + 0.5) O2 \u003d nCO2 + (n + 1) H2O. In reality, internal combustion engines are not as efficient. For example, if oxygen is not enough during the reaction, CO is formed as a result of the reaction. And with a greater lack of oxygen, soot is formed (C).

Plating on metals due to oxidation (rust on iron, patina on copper, darkening of silver) - also from the category of household chemical phenomena.

Take hardware as an example. Rusting (oxidation) occurs under the influence of moisture (air humidity, direct contact with water). The result of this process is iron hydroxide Fe2O3 (more precisely, Fe2O3 * H2O). You can see it as a loose, rough, orange or red-brown coating on the surface of metal products.

Another example is a green patina on the surface of copper and bronze products. It forms over time under the influence of atmospheric oxygen and humidity: 2Cu + O2 + H2O + CO2 \u003d Cu2CO5H2 (or CuCO3 * Cu (OH) 2). The resulting basic copper carbonate also occurs naturally in the form of the mineral malachite.

And another example of a slow oxidative reaction of a metal in domestic conditions is the formation of a dark coating of silver sulfide Ag2S on the surface of silver items: jewelry, cutlery, etc.

"Responsibility" for its occurrence is borne by sulfur particles, which are present in the form of hydrogen sulphide in the air we breathe. Silver can also darken when it comes into contact with foodstuffs (eggs, for example). The reaction looks like this: 4Ag + 2H2S + O2 \u003d 2Ag2S + 2H2O.

Let's go back to the kitchen. Here are some more interesting chemical phenomena: scale formation in the kettle one of them.

In domestic conditions, there is no chemically pure water, it always contains dissolved metal salts and other substances in different concentrations. If the water is saturated with calcium and magnesium salts (bicarbonates), it is called hard. The higher the salt concentration, the harder the water is.

When such water is heated, these salts undergo decomposition into carbon dioxide and insoluble sediment (CaCO3 and MgCO3). You can observe these solid deposits by looking into the kettle (as well as by looking at the heating elements of washing machines, dishwashers, and irons).

In addition to calcium and magnesium (of which carbonate scale follows), iron is also often present in water. During the chemical reactions of hydrolysis and oxidation, hydroxides are formed from it.

By the way, when you are going to get rid of limescale in a kettle, you can observe another example of interesting chemistry in everyday life: ordinary table vinegar and citric acid do well with deposits. A kettle with a vinegar / citric acid solution and water is boiled, after which the scale disappears.

And without another chemical phenomenon, there were no mother's delicious pies and buns: we are talking about extinguishing soda with vinegar.

When mom extinguishes soda in a spoon with vinegar, the following reaction occurs: NaHCO3 + CH3COOH \u003d CH3COONa + H2O + CO2. The resulting carbon dioxide tends to leave the dough - and thereby changes its structure, makes it porous and loose.

By the way, you can tell your mom that it is not at all necessary to extinguish the soda - she will react like that when the dough goes into the oven. The reaction, however, will be slightly worse than when stewing soda. But at a temperature of 60 degrees (or better 200), soda decomposes into sodium carbonate, water and all the same carbon dioxide. True, the taste of ready-made pies and rolls may be worse.

The list of everyday chemical phenomena is no less impressive than the list of such phenomena in nature. Thanks to them, we have roads (making asphalt is a chemical phenomenon), houses (brick burning), beautiful fabrics for clothes (painting). If you think about it, it becomes clear how versatile and interesting the science of chemistry is. And how much benefit can be derived from that of its laws.

I bet you’ve seen something like Mom’s silver ring darken over time. Or how a nail rusts. Or how wooden logs burn to ash. Well, okay, if mom doesn't like silver, and you've never gone on hikes, you saw for sure how a tea bag is brewed in a cup.

What do all these examples have in common? And the fact that they all belong to chemical phenomena.

A chemical phenomenon occurs when some substances turn into others: new substances have a different composition and new properties. If we also recall physics, then remember that chemical phenomena occur at the molecular and atomic level, but do not affect the composition of the nuclei of atoms.

From the point of view of chemistry, this is nothing more than a chemical reaction. And for each chemical reaction, it is necessary to identify characteristic signs:

• a precipitate may form during the reaction;
• the color of the substance may change;
• the result of the reaction may be gas evolution;
• heat can be released or absorbed;
• also, the reaction can be accompanied by the release of light.

Also, a list of conditions necessary for a chemical reaction has long been determined:

• contact: in order to react, substances must touch.
• grinding: for the reaction to proceed successfully, the substances entering into it should be crushed as finely as possible, ideally dissolved;
• temperature: very many reactions directly depend on the temperature of substances (most often they need to be heated, but some on the contrary - to cool to a certain temperature).

By writing down the equation of a chemical reaction in letters and numbers, you thereby describe the essence of a chemical phenomenon. And the law of conservation of mass is one of the most important rules when compiling such descriptions.

Chemical phenomena in nature

You, of course, understand that chemistry takes place not only in test tubes in a school laboratory. The most impressive chemical phenomena you can observe in nature. And their significance is so great that there would be no life on earth, if not for some of the natural chemical phenomena.

So, first of all, let's talk about photosynthesis... This is the process by which plants absorb carbon dioxide from the atmosphere and produce oxygen when exposed to sunlight. This is the oxygen we breathe.

In general, photosynthesis takes place in two phases, and only one needs lighting. Scientists have conducted various experiments and found that photosynthesis occurs even in low light. But with an increase in the amount of light, the process accelerates significantly. It has also been observed that if the plant's illumination is simultaneously increased and the temperature is raised, the rate of photosynthesis increases even more. This happens up to a certain limit, upon reaching which a further increase in illumination ceases to accelerate photosynthesis.

In the process of photosynthesis, photons, which are emitted by the sun, and special pigment molecules of plants, chlorophyll, are involved. In plant cells, it is contained in chloroplasts, thanks to which the leaves are green.

From a chemical point of view, photosynthesis is a chain of transformations, the result of which is oxygen, water and carbohydrates as a store of energy.

Oxygen was originally thought to be formed by the breakdown of carbon dioxide. However, later Cornelius Van Niel found out that oxygen is formed as a result of photolysis of water. Later research has confirmed this hypothesis.

The essence of photosynthesis can be described using the following equation: 6CO 2 + 12H 2 O + light \u003d C 6 H 12 O 6 + 6O 2 + 6H 2 O.

Breath, ours including, – this is also a chemical phenomenon. We breathe in the oxygen produced by the plants, and we breathe out the carbon dioxide.

But not only carbon dioxide is produced by breathing. The main thing in this process is that a large amount of energy is released through breathing, and this method of obtaining it is very effective.

In addition, the intermediate result of different stages of respiration is a large number of different compounds. And they, in turn, serve as the basis for the synthesis of amino acids, proteins, vitamins, fats and fatty acids.

The breathing process is complex and divided into several stages. Each of which uses a large number of enzymes that act as catalysts. The scheme of chemical reactions of respiration is practically the same in animals, plants and even bacteria.

From the point of view of chemistry, respiration is the process of oxidation of carbohydrates (as an option: proteins, fats) with the help of oxygen, as a result of the reaction, water, carbon dioxide and energy are obtained, which cells store in ATP: С 6 Н 12 О 6 + 6О 2 \u003d СО 2 + 6H 2 O + 2.87 * 10 6 J.

By the way, we said above that chemical reactions can be accompanied by the emission of light. This is also true in the case of respiration and its attendant chemical reactions. Some microorganisms can glow (luminesce). Although the energy efficiency of breathing decreases.

Combustion also occurs with the participation of oxygen. As a result, wood (and other solid fuels) turns into ash, which is a substance with a completely different composition and properties. In addition, a large amount of heat and light, as well as gas, is released during combustion.

Of course, not only solids are burning, it was just with their help it was more convenient to give an example in this case.

From a chemical point of view, combustion is an oxidative reaction that proceeds at a very high rate. And at a very, very high reaction rate, an explosion can occur.

The reaction can be schematically written as follows: substance + O 2 → oxides + energy.

We regard it as a natural chemical phenomenon and putrefaction.

In fact, this is the same process as combustion, only it proceeds much more slowly. Rotting is the interaction of complex nitrogen-containing substances with oxygen with the participation of microorganisms. The presence of moisture is one of the factors contributing to the occurrence of decay.

As a result of chemical reactions, ammonia, fatty volatile acids, carbon dioxide, hydroxyacids, alcohols, amines, skatole, indole, hydrogen sulfide, mercaptans are formed from protein. Some of the nitrogen-containing compounds formed as a result of rotting are toxic.

If we turn again to our list of signs of a chemical reaction, we will find many of them in this case. In particular, there is a starting material, a reagent, and reaction products. Of the characteristic features, we note the release of heat, gases (strong smelling), color change.

For the circulation of substances in nature, decay is very important: it allows you to process the proteins of dead organisms into compounds suitable for assimilation by plants. And the circle starts over.

I'm sure you've noticed how easy it is to breathe in summer after a thunderstorm. And the air also becomes especially fresh and takes on a characteristic smell. Every time after a summer thunderstorm, you can observe another chemical phenomenon common in nature - ozone formation.

Ozone (O 3) in its pure form is a blue gas. In nature, the highest concentration of ozone is in the upper atmosphere. There he acts as a shield for our planet. Which protects it from solar radiation from space and does not allow the Earth to cool down, since it also absorbs its infrared radiation.

In nature, ozone is mostly formed due to the irradiation of the air with ultraviolet rays from the Sun (3O 2 + UV light → 2O 3). And also with electrical discharges of lightning during a thunderstorm.

In a thunderstorm, under the influence of lightning, part of the oxygen molecules breaks down into atoms, molecular and atomic oxygen combine, and O 3 is formed.

That is why we feel a special freshness after a thunderstorm, we breathe easier, the air seems more transparent. The point is that ozone is a much stronger oxidizing agent than oxygen. And in small concentration (as after a thunderstorm) it is safe. And even useful, because it decomposes harmful substances in the air. Essentially, it disinfects it.

However, in large doses, ozone is very dangerous for people, animals and even plants, for them it is poisonous.

By the way, the disinfecting properties of laboratory-obtained ozone are widely used for ozonizing water, protecting food from spoilage, in medicine and cosmetology.

Of course, this is not a complete list of amazing chemical phenomena in nature that make life on the planet so diverse and beautiful. You can learn more about them if you look around carefully and keep your ears open. The surroundings are full of amazing phenomena that are just waiting for you to become interested in them.

Chemical phenomena in everyday life

These include those that can be observed in the daily life of a modern person. Some of them are quite simple and obvious, anyone can observe them in their kitchen: for example, making tea. Tea leaves heated with boiling water change their properties, as a result, the composition of the water changes: it acquires a different color, taste and properties. That is, a new substance is obtained.

If sugar is poured into the same tea, a chemical reaction will result in a solution that will again have a set of new characteristics. First of all, new, sweet, taste.

Using the example of strong (concentrated) tea brewing, you can independently carry out one more experiment: clarify the tea with the help of a lemon wedge. Due to the acids contained in lemon juice, the liquid will once again change its composition.

What other phenomena can you observe in everyday life? For example, chemical phenomena include the process combustion of fuel in the engine.

To simplify, the combustion reaction in an engine can be described as oxygen + fuel \u003d water + carbon dioxide.

In general, several reactions take place in the chamber of an internal combustion engine, involving fuel (hydrocarbons), air and an ignition spark. More precisely, not just fuel - a fuel-air mixture of hydrocarbons, oxygen, nitrogen. The mixture is compressed and heated before ignition.

The combustion of the mixture occurs in a split second, as a result, the bond between the hydrogen and carbon atoms is destroyed. Thanks to this, a large amount of energy is released, which drives the piston, and that - the crankshaft.

Subsequently, hydrogen and carbon atoms combine with oxygen atoms, water and carbon dioxide are formed.

Ideally, the reaction of complete fuel combustion should look like this: C n H 2n + 2 + (1.5n+0,5) O 2 = nCO 2 + (n+1) H 2 O... In reality, internal combustion engines are not that efficient. Suppose if oxygen is not enough during the reaction, CO is formed as a result of the reaction. And with a greater lack of oxygen, soot is formed (C).

Plaque formation on metals as a result of oxidation (rust on iron, patina on copper, darkening of silver) - also from the category of household chemical phenomena.

Take hardware as an example. Rusting (oxidation) occurs under the influence of moisture (air humidity, direct contact with water). The result of this process is iron hydroxide Fe 2 O 3 (more precisely, Fe 2 O 3 * H 2 O). You can see it as a loose, rough, orange or reddish-brown coating on the surface of metal products.

Another example is a green coating (patina) on the surface of copper and bronze products. It forms over time under the influence of atmospheric oxygen and humidity: 2Cu + O 2 + H 2 O + CO 2 \u003d Cu 2 CO 5 H 2 (or CuCO 3 * Cu (OH) 2). The resulting basic copper carbonate is also found in nature - in the form of the mineral malachite.

And another example of a slow oxidative reaction of a metal in domestic conditions is the formation of a dark coating of silver sulfide Ag 2 S on the surface of silver items: jewelry, cutlery, etc.

Particles of sulfur, which are present in the form of hydrogen sulfide in the air that we breathe, are "responsible" for its occurrence. Silver can also darken on contact with sulfur-containing foods (eggs, for example). The reaction looks like this: 4Ag + 2H 2 S + O 2 \u003d 2Ag 2 S + 2H 2 O.

Let's go back to the kitchen. Here you can consider a few more curious chemical phenomena: scale formation in the kettle one of them.

In domestic conditions, there is no chemically pure water, metal salts and other substances are always dissolved in it in various concentrations. If the water is saturated with calcium and magnesium salts (bicarbonates), it is called hard. The higher the salt concentration, the harder the water is.

When such water is heated, these salts undergo decomposition into carbon dioxide and insoluble precipitate (CaCO 3 andMgCO 3). You can observe these solid deposits by looking into the kettle (as well as by looking at the heating elements of washing machines, dishwashers, and irons).

In addition to calcium and magnesium (from which carbonate scale is obtained), iron is also often present in water. During chemical reactions of hydrolysis and oxidation, hydroxides are formed from it.

By the way, when you are going to get rid of scale in a teapot, you can observe another example of entertaining chemistry in everyday life: ordinary table vinegar and citric acid do well with deposits. A kettle with a vinegar / citric acid solution and water is boiled, after which the scale disappears.

And without another chemical phenomenon, there would be no delicious mom's pies and buns: we are talking about extinguishing soda with vinegar.

When mom extinguishes soda in a spoon with vinegar, the following reaction occurs: NaHCO 3 + CH 3 COOH \u003dCH 3 COONa + H 2 O + CO 2 ... The resulting carbon dioxide tends to leave the dough - and thereby changes its structure, makes it porous and friable.

By the way, you can tell your mom that it is not at all necessary to extinguish the soda - she will react anyway when the dough enters the oven. The reaction, however, will be slightly worse than when extinguishing soda. But at a temperature of 60 degrees (or better 200), soda decomposes into sodium carbonate, water and all the same carbon dioxide. True, the taste of ready-made pies and rolls may be worse.

The list of everyday chemical phenomena is no less impressive than the list of such phenomena in nature. Thanks to them, we have roads (making asphalt is a chemical phenomenon), houses (baking), beautiful fabrics for clothes (dyeing). If you think about it, it becomes clearly clear how multifaceted and interesting the science of chemistry is. And how much benefit can be derived from understanding its laws.

Among the many, many phenomena invented by nature and man, there are special ones that are difficult to describe and explain. These include burning water... How can this, you ask, because water does not burn, it is used to extinguish fire? How can it burn? Here's the thing.

Water burning is a chemical phenomenon, in which oxygen-hydrogen bonds are broken in water with an admixture of salts under the influence of radio waves. The result is oxygen and hydrogen. And, of course, it is not the water itself that burns, but hydrogen.

At the same time, it reaches a very high combustion temperature (more than one and a half thousand degrees), plus water is formed again during the reaction.

This phenomenon has long been of interest to scientists who dream of learning how to use water as fuel. For example, for cars. While this is something from the field of fantasy, but who knows what scientists will be able to invent very soon. One of the main snags is that when the water burns, more energy is released than is spent on the reaction.

By the way, something similar can be observed in nature. According to one theory, large lone waves that appear as if from nowhere are in fact the result of a hydrogen explosion. The electrolysis of water, which leads to it, is carried out due to the hit of electrical discharges (lightning) on \u200b\u200bthe surface of the salt water of the seas and oceans.

But not only in water, but also on land, one can observe amazing chemical phenomena. If you had a chance to visit a natural cave, for sure you could see there bizarre, beautiful natural "icicles" hanging from the ceiling - stalactites. Another interesting chemical phenomenon explains how and why they appear.

A chemist, looking at a stalactite, sees, of course, not an icicle, but calcium carbonate CaCO 3. The basis for its formation is wastewater, natural limestone, and the stalactite itself is built due to the precipitation of calcium carbonate (downward growth) and the cohesion force of atoms in the crystal lattice (breadth growth).

By the way, similar formations can rise from floor to ceiling - they are called stalagmites... And if stalactites and stalagmites meet and grow together into solid columns, they get the name stalagnates.

Conclusion

There are many amazing, beautiful, dangerous and frightening chemical phenomena happening in the world every day. From many people have learned to benefit: creates building materials, prepares food, makes vehicles travel long distances and much more.

Without many chemical phenomena, life on earth would not have been possible: without the ozone layer, people, animals, plants would not have survived due to ultraviolet rays. Without the photosynthesis of plants, animals and people would have nothing to breathe, and without the chemical reactions of respiration, this issue would not be relevant at all.

Fermentation allows you to cook food, and a similar chemical phenomenon of putrefaction decomposes proteins into simpler compounds and returns them to the circulation of substances in nature.

The formation of oxide when copper is heated, accompanied by a bright glow, combustion of magnesium, melting of sugar, etc. are also considered chemical phenomena. And they find useful applications.

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2014-06-04

Familiarization with mixtures and physical phenomena allowed you to conclude that in mixtures, when physical phenomena are performed, the composition of substances remains unchanged, and the components of mixtures retain their properties. So, during the melting of ice, boiling and freezing of water, its molecules are preserved.

Chemical phenomena. Chemical phenomena are fundamentally different from physical ones. By the beginning of a chemical phenomenon, some substances exist, after which they turn into others.

Chemical phenomena are changes as a result of which some substances turn into others. they are also called chemical reactions.

To make sure that a chemical phenomenon has occurred, it is necessary to detect the formation of new substances. The easiest way to do this is when our vision detects signs of a chemical phenomenon: gas evolution, sediment formation, color change, the appearance of light and heat. In the figures shown in Fig. 39 (see p. 64) examples of chemical phenomena present these signs.

The appearance of smell is also a sign of chemical phenomena. It is enough to keep meat products for several days and even hours in the refrigerator in the summer, as

Provide evidence that the ingredients in the mixtures retain their properties.

The fact that a chemical phenomenon has occurred is evidenced by the appearance of an unpleasant odor.

Signs of chemical phenomena are gas evolution, sediment formation, discoloration, odor, light and heat.

Decay as a natural chemical phenomenon. Have you ever thought about why in a dense forest we do not "drown" in an opal letter and where in nature do fallen tree branches, fruits, dried grass disappear? Indeed, there is something to think about and learn from nature, so as not to have the hassle of garbage.

It turns out that under favorable conditions, the dead remains of plants and animals rot. Decay is a natural chemical phenomenon during which organic substances, mainly proteins, are converted into other organic as well as inorganic substances. As a result, the soil is enriched with nutrients (humus, or humus). Moisture, bacteria, limited air access contribute to rotting. Heat is generated as a sign of this natural chemical phenomenon.

As a result of decay, simple substances are formed, they enter the soil, water, air and are again absorbed by plants and participate in the formation of new organic substances.

Due to decay, dead remains of organisms do not accumulate, and the soil is enriched with humus.

This is an important natural chemical phenomenon in the life of a line is not always desirable, since through it food products become unsuitable for consumption. Ways to prevent decay of organic matter in food are canning, cooking, salting, freezing.

Many chemical phenomena occur in nature.

So in plants from carbon dioxide and water, organic matter and oxygen necessary for life are formed. Thanks to chemical phenomena, the body of animals and humans receives all the substances necessary for growth and development.

piggy bank of knowledge

People have learned to carry out chemical phenomena in laboratories and factories. How important this is now, you are constantly convinced. First of all, we should mention the production of metals, rubber and rubber, plastics, roof and floor coverings, cement, fertilizers for plants, food additives for animals. Man mastered each of these industries at different times. By studying history, you will learn about the Bronze and Iron Ages. The names confirm the importance of the chemical phenomena mastered by the people, thanks to which it was able to replace the stone spear, the wooden harrow with metal tools.

Municipal budgetary educational institution

"Secondary school №93"

Developing a lesson in nature studies

PHYSICAL AND CHEMICAL PHENOMENA IN NATURE AND LIFE

Compiled by a geography teacher

Seityagyaeva Tatiana Alekseevna

Novokuznetsk, 2012

On the subject: "Physical and chemical phenomena in nature and everyday life"

The purpose of the lesson : a lesson in the assimilation of new knowledge by students.

Form of conducting - explanation of a new topic.

Tasks:

Educational: formation of knowledge about physical and chemical phenomena in nature; to consolidate the concepts of substances and phenomena, to acquaint with the process of combustion and oxidation.

Developing: the development of coherent speech skills, the ability to explain concepts, the ability to listen to the teacher and comrades; continue the formation of the ability to establish the relationship between living and inanimate nature; develop the interest of schoolchildren in learning (by showing the importance of the issues studied for science, for the development of creative abilities)

Educational: development of positive motivation for knowledge; the formation of ideas about the unity and beauty of living and inanimate nature.

Equipment: sulfur and iron powder, matches, magnet, candles,banks of differentvolume, paper, plastic comb, video projector, computer.

During the classes

I ... Organizing time.

II ... Updating basic knowledge and skills.

Frontal poll:

What is substance? (Substance is what the body is made of)

Give an example of substances? (glass, water, etc.)

What state will the substance be in? (In solid, liquid and gaseous)

Properties of solids (provide examples)

Properties of liquids, gases (give examples)

What changes can occur with substances? Give examples.

III ... Formation of new concepts, knowledge, skills, development of thinking.

We are surrounded by an endlessly diverse world of substances and phenomena. It is constantly changing. Any changes that occur to bodies are called phenomena. (Slideshow )

The teacher demonstrates natural phenomena while commenting on the slides. After the slide show, students record the diagram from the screen.

Phenomena

Physical Chemical

Physical phenomenon- a change in the state of a substance or its form. Physical properties: color, density, boiling and freezing point, melting point, hardness, plasticity, etc. (Slideshow )

Then the definition is recorded in a notebook.

The task ... Using the pictures, it is necessary to justify why all the depicted phenomena are physical.

Demonstration of experiments in the lesson:

Demonstration of experience number 1. Take a sheet of paper and tear it in half.

What happened to the paper? (students justify the answer) Paper, in spite of the change in shape, remains paper.

Demonstration of experience number 2

If the paper is burned, it turns out that one substance turns into another substance, ash and smoke.

Physical phenomena are extremely diverse. Among them there aremechanical, thermal, electrical, light . ( The slide show is accompanied by an explanation of the new material in the form of a conversation)

Mechanical - phenomena associated with a change in the position of a body in relation to other bodies.

Thermal - phenomena associated with heating and cooling bodies.(Watching a movie of a physical phenomenon - wax melting)

Considerelectrical phenomena. Recall that when you quickly take off your wool sweater, you hear a slight crackling sound. If you do this in the dark, you will also see sparks. This is the simplest electrical phenomenon.

To get acquainted with one more electrical phenomenon, let's do the following experiment.

Demonstration of experience number 3.

Pick up small pieces of paper and place them on the table top. Comb through clean, dry hair with a plastic comb and bring it up to the pieces of paper. What happened? (Student response : small pieces of paper are attracted to the comb).

Bodies that, after rubbing, are capable of attracting small and light objects are calledelectrified. (Slideshow)

The phenomena that are associated with light are calledlight ... Light is emitted by the Sun, stars, a lamp, and some insects such as the firefly beetle.

Chemical phenomenon - a process by which others are formed from some substances. (Demonstration of films of chemical reactions)

Let's consider the main signs of chemical reactions. During chemical reactions, the original substances are converted into other substances with different properties. This can be judged by a number of external signs. The main signs of chemical reactions include:

The release of heat (sometimes light).

Color change.

The appearance of a smell.

Sludge formation.

Gas evolution.

Chemical phenomena occur when substances are heated, when exposed to electric current, strong pressure, etc. Properties of chemical phenomena: combustion and oxidation.Demonstration of experience No. 4.

Light 3 candles, cover 2 of them with jars of different sizes, and do not close 3 candles. Note the burning times in all three cases. What happens to candles?

( Students answer the question, conclude)

Work in notebooks: sign the structure of the candle flame.

Combustion - a chemical reaction in which substances are oxidized, heat and light are released. The combustion process can only take place in the presence of oxygen, heating to the ignition temperature.

During the conversation, the importance of combustion is discussed, how to extinguish small areas of combustion.

Oxidation - it is the interaction of substances with oxygen. (Slide show and in the course of the conversation is conducted with the students, conclusions are drawn)

Oxidation takes place slowly, without the release of light, sometimes with the release of heat.

IV ... Securing new material

1. Consolidation of the material can be carried out on the questions after the paragraph.

2 ... Read an excerpt from The Ugly Duckling by Hans Christian Andersen.

“She called the cat son: he knew how to arch his back, purr and even emit sparks if he was stroked against the grain.”

Answer the questions.

What physical phenomenon is mentioned in the tale? Why did the cat “emit sparks” when stroking it?

3. The work of students in printed notebooks on pages 29-31 task 45,46,47,48,49

V ... Lesson summary

Writing homework in the diaries.

Grading a lesson.

VI ... Setting the task at home

Homework:

Draw examples of physical and chemical phenomena of nature on an album sheet

§13-14 pp. 57-62

Workbook p. 29-31 tasks 49-53.

Bibliography:

Main literature:

1. Pakulova V.M., Ivanova N.V., Nature. Inanimate and alive. (Textbook) .- M .: Bustard, 2002

2. Pakulova V.M., Ivanova N.V., Nature. Inanimate and alive. (Workbook) .- M .: Bustard, 2002

3. Pakulova V.M., Ivanova N.V., Nature. Inanimate and alive. (Workbook for the teacher) .- M .: Bustard, 2002

4. Parfirova L.D. Thematic and lesson planning in nature studies. To the textbook Pakulova V.M., Ivanova N.V. "Nature. Inanimate and alive. Grade 5 "M .: Publishing House" Exam ", 2005

Additional literature:

1. Berdichevskaya L.A., Sonin N.I. Natural science. Grade 5 Collection of tasks for thematic control of students' knowledge. -M .: Bustard, 2003

2. Elkina A.M., Startsev P.E. Natural science. Biological maps.

M .: Bustard, 2005

1. Elkina A.M., Startsev P.E. Natural science. Biological labyrinths. M .: Bustard, 2005

2.