From crude oil extracted from the depths of the earth, various petroleum and waxy products are obtained by distillation. In cosmetics, primarily liquid flowing paraffin (or white) oil, viscous dense petroleum jelly, hard, waxy mountain wax (or ozokerite) and purer paraffin are used.
Paraffin oil is a transparent, odorless, tasteless oily substance that can be of varying densities.
Vaseline is a white, viscous, sticky, oily substance that is odorless. In this form, it is used as an ointment for massage, and also as a base for the preparation of various medicinal ointments.
Ozokerite and paraffin are solid white substances of variable density.
All these petroleum-derived raw materials are widely used in the cosmetics industry due to their low price and good storage stability. They cannot be easily absorbed into the skin, but are an excellent source material for the production of, for example, gel and cosmetic milk, as well as for decorative cosmetics.
Natural oils, due to the presence of unsaturated bonds in them, are less viscous and more fluid than fats. Both oils and fats are esters of fatty acids and glycerol; in nature they are always found in the form of various mixtures. Natural fats quickly deteriorate due to their chemical unsaturation. Therefore, they are often hydrogenated by adding hydrogen atoms at unsaturated bonds. In this form, the fat becomes hard and is better preserved, but at the same time it becomes less suitable for use in cosmetics Villamo H. Cosmetic chemistry. - M.: Mir, 1990..
Fats of plant and animal origin are still used for the production of cosmetic substances, although for the above reasons they are increasingly giving way to synthetic substances, fatty acids, fatty alcohols, etc. The most important plant and animal oils and fats are the following (Table 1) Chemistry in everyday life and in production. / Ed. Selivanova M.I. - M.: Chemistry, 2000..
Table 1 Vegetable and animal oils and fats
In addition to the above, some other natural oils are also used, since they contain certain additional substances. The following are examples.
Raw turtle oil yellow color and has very bad smell(it is obtained by extraction from the genitals and muscles of one of the turtle species). It contains, in particular, vitamins A, O, K and H, as well as linoleic and linolenic acids. After purification, it becomes a usable cosmetic raw material.
Mink oil, like the previous one, is an animal oil rich in vitamins (it is obtained from mink muscles).
In addition to oils, oil from sprouted wheat seeds always contains 2-12% fatty acids. It is well preserved and rich, in particular, in vitamin E, carotene, linoleic and linolenic acids, ergosterol, and also contains large quantities vitamin K.
The most important natural wax used in the manufacture of gels is beeswax. It is a hard yellow or (when bleached) white viscous substance. Beeswax contains 72% of various natural waxes (wax esters), about 14% of free high-molecular fatty acids, free fatty alcohols, etc.
Carnauba wax is obtained from the leaves of the carnauba palm tree. This is the hardest of natural waxes. It mixes well with many fats, oils, waxes, etc., increasing their melting point and increasing the hardness of the composition.
Wool fat is a fat-like substance obtained from sheep's wool as a result of washing it. When 25% water is added to wool fat, a substance called lanolin is obtained. Raw lanolin is yellow-brown in color, but when purified it is almost white. It contains a large amount of cholesterol (largely esterified with various fatty acids), various waxes, as well as free high-molecular fatty acids and fatty alcohols.
Thus, purified lanolin is quite suitable as a starting material. In addition, various products are made from it for various purposes, such as lanolin oil and various fractions of lanolin.
All natural fats and oils are triglycerides, i.e. esters of the tribasic alcohol glycerol. There are no fats or oils in nature in which glycerol is esterified with only one fatty acid; Natural fats are always esters of two or more fatty acids.
Animal fats (such as lard) and vegetable fats can be hydrolyzed with water at high temperature and pressure into fatty acids and glycerol. As a result, mainly stearic acid, palmitic acid and myristic acid are obtained. All three acids are solid, waxy substances, colorless and odorless. In this form, they are excellent raw materials for the preparation of creams, gels and various emulsions.
Natural oils, in addition to the above acids, also contain unsaturated fatty acids, such as oleic acid with one double bond, linoleic acid with two double bonds and linolenic acid with three double bonds. Unsaturated fatty acids and their esters are liquid at room temperature. Due to the presence of double bonds in them, they are very sensitive to decomposition reactions, for example, to the action of microbes, and easily break down into smaller molecules, which often have an unpleasant odor. Thus, they spoil quickly. Therefore, they are usually hydrogenated at double bonds, and from all three of the above unsaturated fatty acids, stearic acid is formed; at the same time they all become hard, which is why this method is called fat hardening.
Wax is formed from an ester of a low molecular weight carboxylic acid, such as acetic acid, and a macromolecular so-called fatty alcohol; fatty alcohols are obtained, in particular, by the decomposition of natural waxes. For the preparation of gels, the most important raw materials are stearic alcohol and cetyl alcohol.
These relatively high molecular weight compounds, obtained by processing natural fats and waxes, are widely used in cosmetics. They are waxy or fat-like substances that adhere well to the skin. They easily mix with sebum and create an excellent addition to the base of creams, gels and other products, improving their properties.
As noted earlier, natural fats, oils and waxes are always mixtures containing a large number of different organic compounds. Therefore, depending on the place of origin and other environmental factors, they differ in their composition and properties. Modern industry, however, strives to produce cosmetic products of constant quality, so sustainable synthetic substances have noticeably replaced natural products.
By processing natural fats and waxes, as described above, fatty acids, fatty alcohols and, of course, glycerin necessary for industrial production are obtained. By combining them again synthetically, pure and stable fats and waxes are obtained. According to their origin and manufacturing method, they are called semi-synthetic products.
Synthetic waxes include esters of stearic, palmitic and myristic acids, obtained in large quantities from natural substances. The second component in them is most often isopropyl alcohol.
Silicones represent a very important group of synthetic fatty and waxy raw materials. These substances are based on a chain of alternating silicon and oxygen atoms, to which side organic groups are attached. An example of silicones is silicone oil, which is a relatively low molecular weight derivative of methylsiloxane.
Speaking about the properties of silicones, it should be noted that they are shelf stable and, in addition, are well tolerated by the body. They do not soften with increasing temperature (this is very important for using them as a liquid component of dense cosmetics), mix well with sebum and form a water-repellent film when used generously.
A polyalcohol (polyol) is an organic compound whose molecule contains more than one hydroxyl group OH. Ethylene glycol and glycerol, having two and three OH groups, respectively, are the simplest polyalcohols. This group also includes all sugars and various glycol derivatives, such as polyethylene glycols, which have already been discussed above. In gels, polyalcohols are used as humectants; in this sense, the most important are glycerin, propylene glycol, sorbitol and fructose.
Colloids include a variety of substances of plant and animal origin that form colloidal solutions with water; many of them are polysaccharides. Of the colloids having a polysaccharide base, the following can be mentioned (Table 2).
Table 2 Colloids having a polysaccharide base
Adhesives are usually products of plant origin. Only a small part of plant adhesives is listed here. Agar-agar, which belongs to the group of alginates, is well known; it is obtained from seaweed and is used to produce gummy-type sweets.
Dextran is produced using certain microorganisms from cane sugar. It is a polymer whose molecular weight ranges between 75,000 and 1,000,000. In addition to being used as a blood plasma substitute, it can be used, for example, to regulate the viscosity of solutions.
Celluloses are a widely used and quite diverse group of substances, of which only three examples are given above. Among the various forms of application for cosmetic purposes, their functions as a viscosity regulator for solutions and as a stabilizer for emulsions are important.
Colloids that have a protein base are, in particular, gelatin, obtained from bones and skins, soy and corn proteins, casein - the protein substance of milk, and albumin, which is obtained from egg whites.
It is characteristic of colloids that they are suitable for forming gels and increasing the viscosity of solutions and emulsions.
Modern emulsion technology uses various types of cellulose, mainly as stabilizers. They are also used as the main component of face masks, as well as in various hair care products.
In addition, protein colloids are used in skin care preparations because they are constructed from amino acid chains of varying lengths and, depending on the processing method, may also contain free amino acids; thus, they can be compared with protein hydrolysates Chemistry for cosmetic products. / Ed. Ovanesyan P.Yu. - Krasnoyarsk: March, 2001. .
At that moment, equilibrium was established, that is, the speed of the forward reaction (A + 2B = B) became equal to the speed of the reverse reaction (B = A + 2B). It is known that the equilibrium concentration of substance A is 0.12 mol/liter, element B is 0.24 mol/liter, and substance C is 0.432 mol/liter. It is required to determine the initial concentrations of A and B.
Study the chemical interaction diagram. It follows from it that one mole (of element B) was formed from one mole of substance A and two moles of substance B. If 0.432 moles of element B were formed in one reaction (according to the conditions of the problem), then, accordingly, 0.432 moles of substance A and 0.864 mole of element B.
Do you know the equilibrium concentrations? starting materials: [A] = 0.12 mol/liter, [B] = 0.24 mol/liter. By adding to these values those that were consumed during the reaction, you will obtain the values of the initial concentrations: [A]0 = 0.12 + 0.432 = 0.552 mol/liter; [B]0 = 0.24 + 0.864 = 1.104 mol/liter.
You can also determine the initial concentrations of substances using the equilibrium constant (Kp) - the ratio of the equilibrium concentrations of the reaction to the product of the equilibrium concentrations of the starting substances. The equilibrium constant is calculated by the formula: Кр = [C]n [D]m /([A]0x[B]0y), where [C] and [D] are the equilibrium concentrations of reaction products C and D; n, m – their coefficients. Accordingly, [A]0, [B]0 are the equilibrium concentrations of elements entering into; x,y – their coefficients.
Knowing the exact scheme of the ongoing reaction, the equilibrium concentration at least one product and initial substance, as well as the value of the equilibrium constant, we can write the conditions of this problem in the form of a system of two equations with two unknowns.
Tip 2: How to determine the equilibrium price and equilibrium quantity
We all know what a market is. Each of us makes purchases every day. From minor ones - buying a ticket on a bus, to large-scale ones - buying houses, apartments, renting land. Whatever the structure of the market: commodity, stock - all its internal mechanisms are essentially the same, but nevertheless require special attention, since a person cannot do without market relations.
Instructions
To find the equilibrium price and equilibrium volume, a number of factors must be determined. Such as the quantity of demand and the quantity of supply. It is these market mechanisms that influence equilibrium. There are also various market structures: monopoly, oligopoly and competition. In monopoly and oligopoly markets, calculate the equilibrium price and the volume does not follow. In fact, there is no balance there. The monopolist company sets itself price and volume of production. In an oligopoly, several firms join together to form a cartel in the same way as monopolists control these factors. But in competition, everything happens according to the rule of the “Invisible Hand” (through supply and demand).
Demand is the buyer's need for a product or service. It is inversely proportional to price and therefore the demand curve on the graph has a negative slope. In other words, the buyer always strives to buy more products at a lower price.
The number of goods and services sellers are ready to supply to the market is supply. Unlike demand, it is directly proportional to price and has a positive slope on the graph. In other words, sellers are trying to sell larger number goods at a higher price.
It is the point of intersection of supply and demand on the graph that is interpreted as equilibrium. Both demand and supply in problems are described by functions in which two variables are present. One is price, the other is production volume. For example: P=16+9Q (P – price, Q – volume). To find the equilibrium price two functions should be equated - supply and demand. Having found the equilibrium price, you need to substitute it into any of the formulas and calculate Q, that is, the equilibrium volume. This principle also works in the opposite direction: first the volume is calculated, then the price.
Example: It is necessary to determine the equilibrium price and the equilibrium volume, if it is known that the quantities of demand and supply are described by the functions: 3P=10+2Q and P=8Q-1, respectively.
Solution:
1) 10+2Q=8Q-1
2) 2Q-8Q=-1-10
3) -6Q=-9
4) Q=1.5 (this is the equilibrium volume)
5) 3P=10+2*1.5
6) 3P=13
7) P=4.333
Ready.
During reactions, some substances are transformed into others, changing their composition. Thus, the "original concentrations" - This concentrations substances before a chemical reaction begins, that is, they are converted into other substances. Of course, such a transformation is accompanied by a decrease in their number. Accordingly, they decrease concentrations starting substances, down to zero values - if the reaction proceeded to completion, irreversibly, and the components were taken in equivalent quantities.
Instructions
Suppose you are given the following task. A certain process took place, during which the initial ones, accepted as A and B, were transformed into products, for example, conditionally B and D. That is, the reaction took place according to the following scheme: A + B = C + D. At a concentration of substance B equal to 0.05 mol /l, and substance G - 0.02 mol/l, a certain chemical equilibrium. Necessary
The chemical properties of substances are revealed in a variety of chemical reactions.
Transformations of substances accompanied by changes in their composition and (or) structure are called chemical reactions. The following definition is often found: chemical reaction is the process of converting starting substances (reagents) into final substances (products).
Chemical reactions are written using chemical equations and diagrams containing the formulas of the starting substances and reaction products. In chemical equations, unlike diagrams, the number of atoms of each element is the same on the left and right sides, which reflects the law of conservation of mass.
On the left side of the equation the formulas of the starting substances (reagents) are written, on the right side - the substances obtained as a result of the chemical reaction (reaction products, final substances). The equal sign connecting the left and right sides indicates that the total number of atoms of the substances involved in the reaction remains constant. This is achieved by placing integer stoichiometric coefficients in front of the formulas, showing the quantitative relationships between the reactants and reaction products.
Chemical equations may contain additional information about the characteristics of the reaction. If a chemical reaction occurs under the influence of external influences (temperature, pressure, radiation, etc.), this is indicated by the appropriate symbol, usually above (or “below”) the equal sign.
A huge number of chemical reactions can be grouped into several types of reactions, which have very specific characteristics.
As classification characteristics the following can be selected:
1. The number and composition of starting substances and reaction products.
2. State of aggregation reagents and reaction products.
3. The number of phases in which the reaction participants are located.
4. The nature of the transferred particles.
5. Possibility of the reaction occurring in forward and reverse directions.
6. The sign of the thermal effect divides all reactions into: exothermic reactions occurring with exo-effect - release of energy in the form of heat (Q>0, ∆H<0):
C + O 2 = CO 2 + Q
And endothermic reactions occurring with the endo effect - the absorption of energy in the form of heat (Q<0, ∆H >0):
N 2 + O 2 = 2NO - Q.
Such reactions are referred to as thermochemical.
Let's take a closer look at each type of reaction.
Classification according to the number and composition of reagents and final substances
1. Compound reactions
When a compound reacts from several reacting substances of relatively simple composition, one substance of a more complex composition is obtained:
As a rule, these reactions are accompanied by the release of heat, i.e. lead to the formation of more stable and less energy-rich compounds.
Reactions of compounds of simple substances are always redox in nature. Compound reactions occurring between complex substances can occur without a change in valency:
CaCO 3 + CO 2 + H 2 O = Ca(HCO 3) 2,
and also be classified as redox:
2FeCl 2 + Cl 2 = 2FeCl 3.
2. Decomposition reactions
Decomposition reactions lead to the formation of several compounds from one complex substance:
A = B + C + D.
The decomposition products of a complex substance can be both simple and complex substances.
Of the decomposition reactions that occur without changing the valence states, noteworthy is the decomposition of crystalline hydrates, bases, acids and salts of oxygen-containing acids:
| t o | ||
| 4HNO3 | = | 2H 2 O + 4NO 2 O + O 2 O. |
2AgNO3 = 2Ag + 2NO2 + O2,
(NH 4) 2 Cr 2 O 7 = Cr 2 O 3 + N 2 + 4H 2 O.
Redox decomposition reactions are especially characteristic for nitric acid salts.
Decomposition reactions in organic chemistry are called cracking:
C 18 H 38 = C 9 H 18 + C 9 H 20,
or dehydrogenation
C4H10 = C4H6 + 2H2.
3. Substitution reactions
In substitution reactions, usually a simple substance reacts with a complex one, forming another simple substance and another complex one:
A + BC = AB + C.
These reactions overwhelmingly belong to redox reactions:
2Al + Fe 2 O 3 = 2Fe + Al 2 O 3,
Zn + 2HCl = ZnСl 2 + H 2,
2KBr + Cl 2 = 2KCl + Br 2,
2КlO 3 + l 2 = 2KlO 3 + Сl 2.
Examples of substitution reactions that are not accompanied by a change in the valence states of atoms are extremely few. It should be noted the reaction of silicon dioxide with salts of oxygen-containing acids, which correspond to gaseous or volatile anhydrides:
CaCO 3 + SiO 2 = CaSiO 3 + CO 2,
Ca 3 (PO 4) 2 + 3SiO 2 \u003d 3СаSiO 3 + P 2 O 5,
Sometimes these reactions are considered as exchange reactions:
CH 4 + Cl 2 = CH 3 Cl + HCl.
4. Exchange reactions
Exchange reactions are reactions between two compounds that exchange their constituents with each other:
AB + CD = AD + CB.
If redox processes occur during substitution reactions, then exchange reactions always occur without changing the valence state of the atoms. This is the most common group of reactions between complex substances - oxides, bases, acids and salts:
ZnO + H 2 SO 4 = ZnSO 4 + H 2 O,
AgNO 3 + KBr = AgBr + KNO 3,
CrCl 3 + ZNaON = Cr(OH) 3 + ZNaCl.
A special case of these exchange reactions is neutralization reactions:
HCl + KOH = KCl + H 2 O.
Typically, these reactions obey the laws of chemical equilibrium and proceed in the direction where at least one of the substances is removed from the reaction sphere in the form of a gaseous, volatile substance, precipitate or low-dissociating (for solutions) compound:
NaHCO 3 + HCl = NaCl + H 2 O + CO 2,
Ca(HCO 3) 2 + Ca(OH) 2 = 2CaCO 3 ↓ + 2H 2 O,
CH 3 COONa + H 3 PO 4 = CH 3 COOH + NaH 2 PO 4.
5. Transfer reactions.
In transfer reactions, an atom or group of atoms moves from one structural unit to another:
AB + BC = A + B 2 C,
A 2 B + 2CB 2 = DIA 2 + DIA 3.
For example:
2AgCl + SnCl 2 = 2Ag + SnCl 4,
H 2 O + 2NO 2 = HNO 2 + HNO 3.
Classification of reactions according to phase characteristics
Depending on the state of aggregation of the reacting substances, the following reactions are distinguished:
1. Gas reactions
| H2+Cl2 | 2HCl. |
2. Reactions in solutions
NaOH(solution) + HCl(p-p) = NaCl(p-p) + H 2 O(l)
3. Reactions between solids
| t o | ||
| CaO(tv) + SiO 2 (tv) | = | CaSiO 3 (sol) |
Classification of reactions according to the number of phases.
A phase is understood as a set of homogeneous parts of a system with the same physical and chemical properties and separated from each other by an interface.
The whole variety of reactions from this point of view can be divided into two classes:
1. Homogeneous (single-phase) reactions. These include reactions occurring in the gas phase and a number of reactions occurring in solutions.
2. Heterogeneous (multiphase) reactions. These include reactions in which the reactants and reaction products are in different phases. For example:
gas-liquid-phase reactions
CO 2 (g) + NaOH(p-p) = NaHCO 3 (p-p).
gas-solid-phase reactions
CO 2 (g) + CaO (tv) = CaCO 3 (tv).
liquid-solid-phase reactions
Na 2 SO 4 (solution) + BaCl 3 (solution) = BaSO 4 (tv) ↓ + 2NaCl (p-p).
liquid-gas-solid-phase reactions
Ca(HCO 3) 2 (solution) + H 2 SO 4 (solution) = CO 2 (r) + H 2 O (l) + CaSO 4 (sol)↓.
Classification of reactions according to the type of particles transferred
1. Protolytic reactions.
TO protolytic reactions include chemical processes, the essence of which is the transfer of a proton from one reacting substance to another.
This classification is based on the protolytic theory of acids and bases, according to which an acid is any substance that donates a proton, and a base is a substance that can accept a proton, for example:
Protolytic reactions include neutralization and hydrolysis reactions.
2. Redox reactions.
These include reactions in which reacting substances exchange electrons, thereby changing the oxidation states of the atoms of the elements that make up the reacting substances. For example:
Zn + 2H + → Zn 2 + + H 2,
FeS 2 + 8HNO 3 (conc) = Fe(NO 3) 3 + 5NO + 2H 2 SO 4 + 2H 2 O,
The vast majority of chemical reactions are redox reactions; they play an extremely important role.
3. Ligand exchange reactions.
These include reactions during which the transfer of an electron pair occurs with the formation of a covalent bond via a donor-acceptor mechanism. For example:
Cu(NO 3) 2 + 4NH 3 = (NO 3) 2,
Fe + 5CO = ,
Al(OH) 3 + NaOH = .
A characteristic feature of ligand exchange reactions is that the formation of new compounds, called complexes, occurs without changing the oxidation state.
4. Reactions of atomic-molecular exchange.
This type of reaction includes many of the substitution reactions studied in organic chemistry that occur via a radical, electrophilic or nucleophilic mechanism.
Reversible and irreversible chemical reactions
Reversible chemical processes are those whose products are capable of reacting with each other under the same conditions under which they were obtained to form the starting substances.
For reversible reactions, the equation is usually written as follows:
Two oppositely directed arrows indicate that, under the same conditions, both forward and reverse reactions occur simultaneously, for example:
CH 3 COOH + C 2 H 5 OH CH 3 COOC 2 H 5 + H 2 O.
Irreversible chemical processes are those whose products are not able to react with each other to form the starting substances. Examples of irreversible reactions include the decomposition of Berthollet salt when heated:
2КlО 3 → 2Кl + ЗО 2,
or oxidation of glucose by atmospheric oxygen:
C 6 H 12 O 6 + 6 O 2 → 6 CO 2 + 6 H 2 O.
Let us treat ourselves at school as chemistry as one of the most difficult and therefore “unloved” subjects, but there is no point in arguing with the fact that chemistry is important and significant, because the argument is doomed to failure. Chemistry, like physics, surrounds us: it molecules, atoms, of which they consist substances, metals, non-metals, connections etc. Therefore chemistry- one of the most important and extensive areas of natural science.
Chemistry–is the science of substances, their properties and transformations.
Chemistry subject are forms of existence of objects of the material world. Depending on what objects (substances) chemistry studies, chemistry is usually divided into inorganic And organic. Examples of inorganic substances are oxygen, water, silica, ammonia and soda, examples of organic substances - methane, acetylene, ethanol, acetic acid and sucrose.
All substances, like buildings, are built from bricks - particles and are characterized a certain set of chemical properties– the ability of substances to take part in chemical reactions.
Chemical reactions – These are the processes of formation of substances of complex composition from simpler ones, the transition of some complex substances to others, the decomposition of complex substances into several substances of simpler composition. In other words, chemical reactions- These are the transformations of one substance into another.
Currently known many millions of substances, new substances are constantly being added to them - both discovered in nature and synthesized by man, i.e. obtained artificially. The number of chemical reactions is unlimited, i.e. immeasurably great.
Let's remember the basic concepts of chemistry - substance, chemical reactions and etc.
The central concept of chemistry is the concept substance. Each substance has unique set of features– physical properties that determine the individuality of each specific substance, for example, density, color, viscosity, volatility, melting and boiling points.
All substances can be in three states of aggregation – hard (ice), liquid (water) and gaseous (steams) depending on external physical conditions. As we see, water H2O presented in all stated conditions.
The chemical properties of a substance do not depend on the state of aggregation, but the physical properties, on the contrary, do. Yes, in any state of aggregation sulfur S upon combustion forms sulfur dioxide SO 2, i.e. exhibits the same chemical property, but physical properties sulfur very different in different states of aggregation: for example, the density of liquid sulfur is equal to 1.8 g/cm 3 solid sulfur 2.1 g/cm 3 and gaseous sulfur 0.004 g/cm3.
The chemical properties of substances are revealed and characterized by chemical reactions. Reactions can occur both in mixtures of different substances and within a single substance. When chemical reactions occur, new substances are always formed.
Chemical reactions are depicted in general terms reaction equation: Reagents → Products, Where reagents are the starting materials taken to carry out the reaction, and products - These are new substances that are formed as a result of a reaction.
Chemical reactions are always accompanied physical effects- it could be absorption or release of heat, changes in the state of aggregation and color of substances; the progress of reactions is often judged by the presence of these effects. Yes, decomposition green mineral malachite accompanied by absorption of heat(this is why the reaction occurs when heated), and as a result of decomposition, solid black copper(II) oxide and colorless substances - carbon dioxide CO 2 and liquid water H 2 O.
Chemical reactions must be distinguished from physical processes, which change only the external shape or state of aggregation 
tion of the substance (but not its composition); The most common physical processes are crushing, pressing, co-fusion, mixing, dissolving, filtering the precipitate, distillation.
Using chemical reactions, it is possible to obtain practically important substances that are found in limited quantities in nature ( nitrogen fertilizers) or do not occur at all ( synthetic drugs, chemical fibers, plastics). In other words, chemistry allows us to synthesize substances necessary for human life. But chemical production also brings a lot of harm to the environment - in the form of pollution, harmful emissions, poisoning of flora and fauna, That's why the use of chemistry must be rational, careful and appropriate.
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