Chemical phenomena examples 8. "Physical and chemical phenomena (chemical reactions)
For the last 200 years of humanity studied the properties of substances better than in the entire history of the development of chemistry. Naturally, the number of substances is also growing rapidly, this is primarily due to the development of various methods of obtaining substances.
V Everyday life we are faced with many substances. Among them are water, iron, aluminum, plastic, soda, salt and many others. Substances that exist in nature, for example, oxygen and nitrogen contained in the air, substances dissolved in water and of natural origin, are called natural substances. Aluminum, zinc, acetone, lime, soap, aspirin, polyethylene and many other substances do not exist in nature.
They are obtained in the laboratory and produced by industry. Artificial substances do not occur in nature, they are created from natural substances. Some naturally occurring substances can also be obtained in a chemical laboratory.
So, when potassium permanganate is heated, oxygen is released, and when chalk is heated - carbon dioxide. Scientists have learned how to turn graphite into diamond, grow crystals of ruby, sapphire and malachite. So, along with substances of natural origin, there is a huge variety of artificially created substances that are not found in nature.
Non-naturally occurring substances are produced in various enterprises: factories, factories, combines, etc.
Under conditions of exhaustion natural resources of our planet, now chemists are faced with an important task: to develop and implement methods with the help of which it is possible, artificially, in a laboratory or industrial production, to obtain substances that are analogs of natural substances. For example, the reserves of fossil fuels in nature are running out.
The moment may come when oil and natural gas run out. Already, new fuels are being developed that would be just as efficient but would not pollute environment... To date, mankind has learned to artificially obtain various precious stones, for example, diamonds, emeralds, beryls.
State of matter
Substances can exist in several states of aggregation, three of which are known to you: solid, liquid, gaseous. For example, water in nature exists in all three states of aggregation: solid (in the form of ice and snow), liquid (liquid water) and gaseous (water vapor). There are known substances that cannot exist under normal conditions in all three states of aggregation. For example, carbon dioxide is such a substance. At room temperature, it is an odorless and colorless gas. At a temperature of -79 ° C this substance "freezes" and turns into a solid state of aggregation... The common (trivial) name for such a substance is "dry ice". This name is given to this substance due to the fact that "dry ice" turns into carbon dioxide without melting, that is, without a transition to a liquid state of aggregation, which is present, for example, near water.
Thus, an important conclusion can be drawn. A substance during the transition from one state of aggregation to another does not transform into other substances. The very process of a certain change, transformation, is called a phenomenon.
Physical phenomena. Physical properties of substances.
Phenomena in which substances change their state of aggregation, but at the same time do not turn into other substances, are called physical. Each individual substance has certain properties. The properties of substances can be different or similar to each other. Each substance is described using a set of physical and chemical properties. Let's take water as an example. Water freezes and turns into ice at a temperature of 0 ° C, and boils and turns into steam at a temperature of + 100 ° C. These phenomena are physical, since water has not turned into other substances, only a change in the state of aggregation occurs. Freezing and boiling points are physical properties specific to water.
The properties of substances, which are determined by measurements or visually in the absence of the transformation of some substances into others, are called physical
Alcohol evaporation, like water evaporation- physical phenomena, substances at the same time change the state of aggregation. After the experiment, you can make sure that alcohol evaporates faster than water - these are the physical properties of these substances.
The main physical properties of substances include the following: state of aggregation, color, odor, solubility in water, density, boiling point, melting point, thermal conductivity, electrical conductivity. Physical properties such as color, smell, taste, crystal shape can be determined visually, using the senses, and density, electrical conductivity, melting and boiling points are determined by measurement. Information about physical properties ah of many substances are collected in specialized literature, for example, in reference books. The physical properties of a substance depend on its state of aggregation. For example, the density of ice, water and water vapor is different.
Oxygen gas is colorless and liquid oxygen is blue Knowledge of the physical properties helps to "recognize" a lot of substances. For example, copper- the only metal of red color. Only table salt has a salty taste. Iodine Is an almost black solid which, when heated, turns into a violet vapor. In most cases, to determine a substance, several of its properties must be considered. As an example, we characterize the physical properties of water:
- color - colorless (in a small volume)
- smell - odorless
- state of aggregation - liquid under normal conditions
- density - 1 g / ml,
- boiling point - + 100 ° С
- melting point - 0 ° С
- thermal conductivity - low
- electrical conductivity - pure water does not conduct electricity
Crystalline and amorphous substances
When describing the physical properties of solids, it is customary to describe the structure of a substance. If you look at a sample of table salt under a magnifying glass, you will notice that salt is composed of many tiny crystals. Very large crystals can be found in salt deposits. Crystals - solids shaped like regular polyhedra Crystals can be of various shapes and sizes. Crystals of certain substances, such as cooking salt – fragile, easy to destroy... There are crystals that are quite hard. For example, diamond is considered one of the hardest minerals. If you look at the crystals of table salt under a microscope, you will notice that they all have a similar structure. If we consider, for example, glass particles, then they will all have a different structure - such substances are called amorphous. Amorphous substances include glass, starch, amber, beeswax. Amorphous substances- substances that do not have a crystalline structure
Chemical phenomena. Chemical reaction.
If, in physical phenomena, substances, as a rule, only change the state of aggregation, then in chemical phenomena, some substances are transformed into other substances. Here are some simple examples: burning of a match is accompanied by charring of wood and the release of gaseous substances, that is, irreversible transformation of wood into other substances occurs. Another example: over time, bronze sculptures are covered with a bloom of green. The fact is that copper is part of the bronze. This metal slowly interacts with oxygen, carbon dioxide and moisture in the air, as a result, new green substances are formed on the surface of the sculpture. Chemical phenomena- the phenomenon of transformation of some substances into others The process of interaction of substances with the formation of new substances is called a chemical reaction. Chemical reactions are happening all around us. Chemical reactions take place in ourselves. In our body, transformations of many substances are continuously occurring, substances react with each other, forming reaction products. Thus, in a chemical reaction there are always reactive substances, and substances formed as a result of the reaction.
- Chemical reaction- the process of interaction of substances, as a result of which new substances with new properties are formed
- Reagents- substances that enter into a chemical reaction
- Products- substances formed as a result of a chemical reaction
The chemical reaction is depicted in general view reaction scheme REAGENTS -> PRODUCTS
- reagents- starting materials taken for the reaction;
- products- new substances formed as a result of the reaction.
Any chemical phenomena (reactions) are accompanied by certain signs, with the help of which chemical phenomena can be distinguished from physical ones. These signs include a change in the color of substances, gas evolution, sediment formation, heat evolution, light emission.
Many chemical reactions accompanied by the release of energy in the form of heat and light. As a rule, such phenomena are accompanied by combustion reactions. In combustion reactions in air, substances react with oxygen in the air. So, for example, the metal magnesium flares up and burns in the air with a bright blinding flame. That is why the flash of magnesium was used in photographs in the first half of the 20th century. In some cases, it is possible to release energy in the form of light, but without the release of heat. One of the species of Pacific plankton is capable of emitting bright blue light, clearly visible in the dark. The release of energy in the form of light is the result of a chemical reaction that occurs in the organisms of this type of plankton.
Summary of the article:
- There are two large groups of substances: substances of natural and artificial origin.
- Under normal conditions, substances can be in three states of aggregation
- The properties of substances, which are determined by measurements or visually in the absence of the transformation of some substances into others, are called physical
- Crystals are solids in the form of regular polyhedrons
- Amorphous substances - substances that do not have a crystalline structure
- Chemical phenomena - the phenomenon of transformation of some substances into others
- Reagents - Substances that undergo a chemical reaction
- Products - substances formed as a result of a chemical reaction
- Chemical reactions can be accompanied by the evolution of gas, sediment, heat, light; discoloration of substances
- Combustion is a complex physicochemical process of converting initial substances into combustion products in the course of a chemical reaction, accompanied by an intense release of heat and light (flame)
Physical changes are not related to chemical reactions and the creation of new products, such as melting ice. As a rule, such transformations are reversible. In addition to examples of physical phenomena, there are also chemical transformations in nature and in everyday life, during which new products are formed. Such chemical phenomena (examples will be discussed in the article) are irreversible.
Chemical changes
Chemical change can be thought of as any phenomenon that allows scientists to measure Chemical properties... Many reactions are also examples of chemical phenomena. While it is not always easy to tell that it was a chemical change that occurred, there are some telltale signs. What are chemical phenomena? Here are some examples. This can be a change in the color of a substance, temperature, the formation of bubbles or (in liquids) precipitation. The following examples of chemical phenomena in life can be cited:
- Rust on the iron.
- Burning wood.
- Food metabolism in the body.
- Mixing acid and alkali.
- Cooking an egg.
- Digestion of sugar by amylase in saliva.
- Blending baking soda and vinegar to produce carbon dioxide gas.
- Baking a cake.
- Metal galvanization.
- Batteries.
- Explosion of fireworks.
- Rotting bananas.
- Formation of lactic acid products.
And this is not the whole list. You can consider some of these points in more detail.
Outdoor fire using wood
Fire - this is also an example of a chemical phenomenon. This is the rapid oxidation of the material in an exothermic chemical combustion process, the release of heat, light and various reaction products. The fire is hot because the weak double bond in molecular oxygen O 2 is converted to stronger bonds in the combustion products of carbon dioxide and water. High energy is released (418 kJ for 32 g O 2); the bonding energies of the fuel play only a minor role here. At a certain point in the combustion reaction, called the flash point, a flame is formed.
It is the visible part of the fire and is composed primarily of carbon dioxide, water vapor, oxygen and nitrogen. If the temperature is high enough, gases can become ionized to produce plasma. Depending on which substances are ignited and which impurities are supplied from the outside, the color of the flame and the intensity of the fire will be different. Fire, in its most common form, can lead to a fire that can cause physical damage if burned. Fire is an important process that affects ecological systems around the world. The beneficial effects of fire include stimulating growth and maintaining various ecological systems.
Rust
Just like fire, the rusting process is also an oxidative process. Just not so fast. Rust is an iron oxide, usually a red oxide, formed by the redox reaction of iron and oxygen in the presence of water or air. Several forms of rust are distinguished both visually and spectroscopically and are formed under different circumstances. Given enough time, oxygen and water, any mass of iron will eventually turn completely into rust and decompose. The surface is flaky and loose and does not protect the underlying iron, unlike the patina of copper surfaces.
An example of a chemical phenomenon such as rusting is general term for corrosion of iron and its alloys such as steel. Many other metals corrode similarly, but the resulting oxides are not commonly referred to as rust. There are other forms of this reaction as a result of the reaction between iron and chloride in an oxygen-deprived environment. An example is the reinforcement used in underwater concrete pillars, which generates green rust.
Crystallization
Crystalline growth is another example of a chemical phenomenon. It is a process in which a pre-existing crystal grows larger as the number of molecules or ions increases at their positions in the crystal lattice. A crystal is defined as atoms, molecules or ions arranged in an ordered repeating pattern, a crystal lattice that extends in all three spatial dimensions. Thus, crystal growth differs from liquid droplet growth in that during growth, molecules or ions must fall into the correct lattice positions for an ordered crystal to grow.
When molecules or ions are placed in a position other than those in an ideal crystal lattice, crystal defects are formed. Typically, molecules or ions in a crystal lattice are trapped in the sense that they cannot move from their positions, and therefore crystal growth is often irreversible, since when the molecules or ions are in place in the growing lattice, they are fixed in it. Crystallization is a common process in both industry and natural world, and crystallization is usually understood as consisting of two processes. If a crystal did not previously exist, then a new crystal must be nucleated, and then it must undergo growth.
The chemical origin of life
The chemical origin of life refers to the conditions that could have existed and, therefore, contributed to the emergence of the first duplicated life forms.
The prime example of chemical phenomena in nature is life itself. It is believed that the combination of physical and chemical reactions was able to lead to the appearance of the first molecules, which, reproducing, led to the emergence of life on the planet.
The world around us, with all its richness and diversity, lives according to laws that are quite easy to explain with the help of sciences such as physics and chemistry. And even at the heart of the vital activity of such a complex organism as a person, there is nothing else but chemical phenomena and processes.
Definitions and examples
An elementary example is a kettle on fire. After a while, the water will begin to heat up, then boil. We will hear a characteristic hiss, streams of steam will fly out of the neck of the kettle. Where did it come from, because it was not originally in the dishes! Yes, but water, at a certain temperature, begins to turn into gas, changes its physical state from liquid to gaseous. Those. it remained the same water, only now in the form of steam. it
And we will see the chemical phenomena if we put a bag of tea leaves in boiling water. The water in a glass or other container will turn reddish-brown. A chemical reaction will take place: under the influence of heat, the tea leaves will begin to steam, emitting color pigments and flavoring properties inherent in this plant. We will get a new substance - a drink with specific, characteristic only qualitative characteristics. If we add a few tablespoons of sugar there, it will dissolve (physical reaction), and the tea will become sweet. Thus, physical and chemical phenomena are often related and interdependent. For example, if the same tea bag is placed in cold water, the reaction will not occur, the tea leaves and water will not interact, and the sugar will not want to dissolve either.
Thus, chemical phenomena are those in which some substances are converted into others (water into tea, water into syrup, firewood into ash, etc.). Otherwise, a chemical phenomenon is called a chemical reaction.
Physical phenomena are those in which chemical composition matter remains the same, but the size of the body, shape, etc. change. (deformed spring, water frozen into ice, tree branch broken in half).
Conditions of occurrence and flow
We can judge whether chemical and physical phenomena occur by some signs and changes that are observed in a particular body or substance. So, most chemical reactions are accompanied by the following "identification marks":
- as a result or during the course of such a precipitate is formed;
- there is a change in the color of the substance;
- gas may be released, for example carbon monoxide when burning;
- there is absorption or, conversely, the release of heat;
- light emission possible.
For chemical phenomena to be observed, i.e. reactions took place, some conditions are necessary:
- the reacting substances must be in contact, be in contact with each other (i.e. the same tea leaves must be poured into a mug with boiling water);
- it is better to grind the substances, then the reaction will proceed faster, the interaction will sooner occur (granulated sugar is more likely to dissolve, melt in hot water than lumpy);
- for many reactions to occur, it is necessary to change the temperature regime of the reacting components by cooling or heating them to a certain temperature.
You can observe the chemical phenomenon empirically. But you can describe it on paper using a chemical chemical reaction).
Some of these conditions also work for the occurrence of physical phenomena, for example, a change in temperature or direct contact of objects, bodies with each other. For example, if you hit the nail head hard enough with a hammer, it can deform, lose its normal shape. But it will remain the head of the nail. Or, when you turn on the light bulb in the network, the tungsten filament inside it will start to warm up and glow. However, the substance from which the filament is made will remain the same tungsten.
Description of physical processes and phenomena occurs through physical formulas, the solution of physical problems.
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Zaporizhzhya comprehensive schoolІ-ІІІ steps No. 90
Chemical phenomena in everyday life and everyday life
Grade 7-A student
Dmitry Baluev
Introduction
chemical reaction fuel oxidation
The world around us, with all its richness and diversity, lives according to laws that are quite easy to explain with the help of sciences such as physics and chemistry. And even at the heart of the vital activity of such a complex organism as a person, there is nothing else but chemical phenomena and processes.
Surely, you have often noticed something like how your mother's silver ring darkens over time. Or how a nail rusts. Or how wooden logs burn to ash. But even if your mother does not like silver, and you have 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.
So, the most common examples of chemical phenomena in life and everyday life:
rusting nail
combustion of fuel
precipitation
fermentation of grape juice
rotting paper
synthesis of spirits
darkening silver earring
the appearance of a green bloom on bronze
scale formation in boilers
extinguishing soda with vinegar
rotting meat
burning paper
Want more details? An elementary example is a kettle on fire. After a while, the water will begin to heat up, then boil. We will hear a characteristic hiss, streams of steam will fly out of the neck of the kettle. Where did it come from, because it was not originally in the dishes! Yes, but water, at a certain temperature, begins to turn into gas, changes its physical state from liquid to gaseous. Those. it remained the same water, only now in the form of steam. This is a physical phenomenon.
And we will see the chemical phenomena if we put a bag of tea leaves in boiling water. The water in a glass or other container will turn red-brown. A chemical reaction will take place: under the influence of heat, the tea leaves will begin to steam, emitting color pigments and flavoring properties inherent in this plant. We will get a new substance - a drink with specific, characteristic only qualitative characteristics. If we add a few tablespoons of sugar there, it will dissolve (physical reaction), and the tea will become sweet (chemical reaction). Thus, physical and chemical phenomena are often related and interdependent. For example, if the same tea bag is placed in cold water, the reaction will not occur, the tea leaves and water will not interact, and the sugar will not dissolve either.
Thus, chemical phenomena are those in which some substances are converted into others (water into tea, water into syrup, firewood into ash, etc.). Otherwise, a chemical phenomenon is called a chemical reaction.
We can judge whether chemical phenomena occur by some signs and changes that are observed in a particular body or substance. So, most chemical reactions are accompanied by the following "identification marks":
as a result or during the course of such a precipitate is formed;
there is a change in the color of the substance;
gas may be released, for example carbon monoxide when burning;
there is absorption or, conversely, the release of heat;
light emission possible.
For chemical phenomena to be observed, i.e. reactions took place, some conditions are necessary:
the reacting substances must be in contact, be in contact with each other (i.e. the same tea leaves must be poured into a mug with boiling water);
it is better to grind the substances, then the reaction will proceed faster, the interaction will sooner occur (granulated sugar is more likely to dissolve, melt in hot water than lumpy);
for many reactions to occur, it is necessary to change the temperature regime of the reacting components by cooling or heating them to a certain temperature.
You can observe the chemical phenomenon empirically. But you can describe it on paper using a chemical equation (the equation of a chemical reaction).
Some of these conditions also work for the occurrence of physical phenomena, for example, a change in temperature or direct contact of objects, bodies with each other. For example, if you hit the nail head hard enough with a hammer, it can deform, lose its normal shape. But it will remain the head of the nail. Or, when you turn on the light bulb in the network, the tungsten filament inside it will start to warm up and glow. However, the substance from which the filament is made will remain the same tungsten.
But let's look at a few more examples. After all, we all understand that chemistry takes place not only in test tubes in a school laboratory.
1. Chemical phenomena in everyday life
These include those that can be observed in everyday life. modern man... Some of them are quite simple and obvious, anyone can observe them in their kitchen, as an example of brewing tea.
Using the strong (concentrated) tea brew as an example, you can independently carry out one more experiment: clarify the tea with 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 combustion of fuel in an engine.
To simplify, the combustion reaction of fuel in an engine can be described as follows: oxygen + fuel = water + carbon dioxide.
In general, several reactions take place in the chamber of an internal combustion engine, in which fuel (hydrocarbons), air and an ignition spark are involved. 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 number of energy that 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 = nCO2 + (n + 1) H2O. 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).
The formation of plaque on metals as a result of oxidation (rust on iron, patina on copper, darkening of silver) is also from the category of household chemical phenomena.
Let's 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 reddish-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 = Cu2CO5H2 (or CuCO3 * Cu (OH) 2). The resulting basic copper carbonate is also found in nature - in the form of the mineral malachite.
And another example of slow oxidative reaction metal in domestic conditions is the formation of a dark coating of silver sulfide Ag2S on the surface of silver items: jewelry, cutlery, etc.
Particles of sulfur, which are present in the form of hydrogen sulfide in the air 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 + 2H2S + O2 = 2Ag2S + 2H2O.
Let's go back to the kitchen. Here you can consider a few more curious chemical phenomena: the formation of scale in a teapot is one of them.
Under 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 decompose into carbon dioxide and an insoluble precipitate (CaCO3 and MgCO3). You can observe these solid deposits by looking into the kettle (as well as 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. In the course of 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 tasty 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: NaHCO3 + CH3COOH = CH3COONa + H2O + CO2. 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 mother that it is not at all necessary to extinguish the soda - she will react like that when the dough enters the oven. The reaction, however, will be slightly worse than when quenching 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 finished 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 (dyeing). If you think about it, it becomes clear how multifaceted and interesting science chemistry. And how much benefit can be derived from understanding its laws.
2. Interesting chemical phenomena
I would like to add some interesting things. Among the many, many phenomena invented by nature and man, there are special ones that are difficult to describe and explain. Combustion of water also belongs to them. How is this, you may ask, because water does not burn, it is used to extinguish fire? How can it burn? Here's the thing.
Combustion of water 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 realm 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, appearing 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 the 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. How and why they appear is explained by another interesting chemical phenomenon.
A chemist, looking at a stalactite, sees, of course, not an icicle, but calcium carbonate CaCO3. 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 are called 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 Construction Materials, prepares food, makes vehicles travel great 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 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 cycle of substances in nature.
The formation of oxide when copper is heated, accompanied by a bright glow, the burning of magnesium, melting of sugar, etc. are also considered chemical phenomena. And they find useful applications.
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