Chemical factors

Chemical factors. Chemicals are widely used by humans in production and in everyday life (preservatives, detergents, cleaning agents, disinfectants, as well as products for painting and gluing various objects).

All chemicals used in everyday life are safe for health in small quantities. However, violating the rules for their use can have an adverse effect on the body.

Chemicals should also include medicines, which are prescribed by doctors for various diseases. Many modern medicines come in the form of multi-colored dragees and have a very attractive appearance, so children often confuse them with candies. Meanwhile, one tablet is enough to cause serious poisoning in a child, life-threatening.

Biological factors

Biological factors. The forms of existence of living matter on Earth are extremely diverse: from single-celled protozoa to highly organized biological organisms. All known microorganisms can be divided into three groups: completely safe for humans (saprophytes), we are constantly in contact with them, but this never causes diseases; certainly harmful, i.e. dangerous to human health (meeting with them is always fraught with the development infectious disease However, this happens when the body does not have appropriate protection); conditionally pathogenic (these are microorganisms that under normal conditions do not cause any diseases in humans, however, when the body is weakened due to a cold or chronic disease, malnutrition, vitamin deficiency, stress, fatigue, etc., they can cause diseases). A group of particularly dangerous microorganisms that cause severe diseases in humans has been identified. These are, for example, the causative agents of smallpox, plague, cholera, tularemia, anthrax, and polio.

So, biological environmental factors include many biological objects with which the human body continuously interacts. There are:

Natural and socio-biological logical factors affecting the human body are inextricably linked with environmental issues.

Ecology (Greek, oikos - house, dwelling, homeland + logos - concept, teaching) is both a field of knowledge, and a part of biology, and academic discipline, and integrated science. Ecology examines the relationships of organisms with each other and with the inanimate components of nature: the Earth (its biosphere). Human ecology studies the patterns of human interaction with nature, the problems of preserving and promoting health. Man depends on the conditions of his environment in the same way as nature depends on man. Meanwhile, the impact of industrial activities on the environment (pollution of the atmosphere, soil, water bodies with industrial waste, deforestation, increased radiation as a result of accidents and technological violations) threatens the existence of man himself. For example, in major cities The natural habitat is significantly deteriorating, the rhythm of life, the psycho-emotional situation of work, life, and recreation are disrupted, and the climate is changing. In cities, the intensity of solar radiation is 15 - 20% lower than in the surrounding areas, but the average annual temperature is 1 - 2 degrees higher, daily and seasonal fluctuations are less significant, atmospheric pressure is lower, and the air is polluted. All these changes have an extremely adverse impact on a person’s physical and mental health. About 80 diseases modern man- the result of the deteriorating environmental situation on the planet. Environmental issues are directly related to the process of organizing and conducting systematic physical exercise and sports, as well as the conditions in which they occur.

The state in which the rates of forward and reverse reactions are equal is called chemical equilibrium. Reversible reaction equation in general view:

Forward reaction rate v 1 =k 1 [A] m [B] n, reverse reaction speed v 2 =k 2 [C] p [D] q, where in square brackets are equilibrium concentrations. By definition, at chemical equilibrium v 1 =v 2, where from

K c =k 1 /k 2 = [C] p [D] q / [A] m [B] n,

where Kc is the chemical equilibrium constant, expressed in terms of molar concentrations. The given mathematical expression is often called the law of mass action for a reversible chemical reaction: the ratio of the product of the equilibrium concentrations of the reaction products to the product of the equilibrium concentrations of the starting substances.

The position of chemical equilibrium depends on the following reaction parameters: temperature, pressure and concentration. The influence that these factors have on a chemical reaction is subject to a pattern that was expressed in general terms in 1884 by the French scientist Le Chatelier. The modern formulation of Le Chatelier's principle is as follows:

If an external influence is exerted on a system in a state of equilibrium, the system will move to another state in such a way as to reduce the effect of the external influence.

Factors influencing chemical equilibrium.

1. Effect of temperature. In each reversible reaction, one of the directions corresponds to an exothermic process, and the other to an endothermic process.

As the temperature increases, the chemical equilibrium shifts in the direction of the endothermic reaction, and as the temperature decreases, in the direction of the exothermic reaction.

2. Effect of pressure. In all reactions involving gaseous substances, accompanied by a change in volume due to a change in the amount of substance during the transition from starting substances to products, the equilibrium position is influenced by the pressure in the system.
The influence of pressure on the equilibrium position obeys the following rules:

As pressure increases, the equilibrium shifts towards the formation of substances (initial or products) with a smaller volume.

3. Effect of concentration. The influence of concentration on the state of equilibrium is subject to the following rules:

When the concentration of one of the starting substances increases, the equilibrium shifts towards the formation of reaction products;
When the concentration of one of the reaction products increases, the equilibrium shifts towards the formation of the starting substances.

Questions for self-control:

1. What is the rate of a chemical reaction and what factors does it depend on? What factors does the rate constant depend on?

2. Create an equation for the rate of the reaction of the formation of water from hydrogen and oxygen and show how the rate changes if the concentration of hydrogen is increased three times.

3. How does the reaction rate change over time? What reactions are called reversible? What characterizes the state of chemical equilibrium? What is called the equilibrium constant, on what factors does it depend?

4. What external influences can disrupt the chemical balance? In which direction will the equilibrium mix when the temperature changes? Pressure?

5. How can a reversible reaction be shifted in a certain direction and completed?

Lecture No. 12 (problematic)

Solutions

Target: Give qualitative conclusions about the solubility of substances and a quantitative assessment of solubility.

Key words: Solutions – homogeneous and heterogeneous; true and colloidal; solubility of substances; concentration of solutions; solutions of non-electroyls; Raoult's and van't Hoff's laws.

Plan.

1. Classification of solutions.

2. Concentration of solutions.

3. Solutions of non-electrolytes. Raoult's laws.

Classification of solutions

Solutions are homogeneous (single-phase) systems of variable composition, consisting of two or more substances (components).

According to the nature of their state of aggregation, solutions can be gaseous, liquid and solid. Typically, a component that, under given conditions, is in the same state of aggregation as the resulting solution is considered a solvent, while the remaining components of the solution are considered solutes. In the case of the same state of aggregation of the components, the solvent is considered to be the component that predominates in the solution.

Depending on the particle size, solutions are divided into true and colloidal. In true solutions (often called simply solutions), the solute is dispersed to the atomic or molecular level, the particles of the solute are not visible either visually or under a microscope, and move freely in the solvent environment. True solutions are thermodynamically stable systems that are indefinitely stable in time.

The driving forces for the formation of solutions are entropy and enthalpy factors. When gases are dissolved in a liquid, entropy always decreases ΔS< 0, а при растворении кристаллов возрастает (ΔS >0). The stronger the interaction between the solute and the solvent, the greater the role of the enthalpy factor in the formation of solutions. The sign of the change in the enthalpy of dissolution is determined by the sign of the sum of all thermal effects of the processes accompanying dissolution, of which the main contribution is made by the destruction of the crystal lattice into free ions (ΔH > 0) and the interaction of the resulting ions with solvent molecules (soltivation, ΔH< 0). При этом независимо от знака энтальпии при растворении (абсолютно нерастворимых веществ нет) всегда ΔG = ΔH – T·ΔS < 0, т. к. переход вещества в раствор сопровождается значительным возрастанием энтропии вследствие стремления системы к разупорядочиванию. Для жидких растворов (расплавов) процесс растворения идет самопроизвольно (ΔG < 0) до установления динамического равновесия между раствором и твердой фазой.

The concentration of a saturated solution is determined by the solubility of the substance at a given temperature. Solutions with lower concentrations are called unsaturated.

Solubility for various substances fluctuates within significant limits and depends on their nature, the interaction of solute particles with each other and with solvent molecules, as well as on external conditions (pressure, temperature, etc.)

In chemical practice, the most important solutions are those prepared on the basis of a liquid solvent. Liquid mixtures in chemistry are simply called solutions. The most widely used inorganic solvent is water. Solutions with other solvents are called non-aqueous.

Solutions are of extremely great practical importance; many chemical reactions, including those underlying metabolism in living organisms.

Concentration of solutions

Important characteristic solutions is their concentration, which expresses the relative amount of components in the solution. There are mass and volume concentrations, dimensional and dimensionless.

TO dimensionless concentrations (shares) include the following concentrations:

Mass fraction of solute W(B) expressed as a fraction of a unit or as a percentage:

where m(B) and m(A) are the mass of solute B and the mass of solvent A.

The volume fraction of the solute σ(B) is expressed in fractions of a unit or volume percent:

where Vi is the volume of the solution component, V(B) is the volume of the dissolved substance B. Volume percentages are called degrees *).

*) Sometimes the volume concentration is expressed in parts per thousand (ppm, ‰) or in parts per million (ppm), ppm.

The mole fraction of the dissolved substance χ(B) is expressed by the relation

The sum of the mole fractions of the k components of the solution χ i is equal to unity

TO dimensional concentrations include the following concentrations:

The molality of the solute C m (B) is determined by the amount of substance n(B) in 1 kg (1000 g) of solvent, the dimension is mol/kg.

Molar concentration of substance B in solution C(B) – content of the amount of dissolved substance B per unit volume of solution, mol/m3, or more often mol/liter:

where μ(B) is the molar mass of B, V is the volume of the solution.

Molar concentration of equivalents of substance B C E (B) (normality - outdated) is determined by the number of equivalents of a dissolved substance per unit volume of solution, mol/liter:

where n E (B) is the amount of substance equivalents, μ E is the molar mass of the equivalent.

Titer of solution of substance B( T B) is determined by the mass of the solute in g contained in 1 ml of solution:

G/ml or g/ml.

Mass concentrations ( mass fraction, percentage, molal) do not depend on temperature; volumetric concentrations refer to a specific temperature.

All substances are capable of dissolving to one degree or another and are characterized by solubility. Some substances are unlimitedly soluble in each other (water-acetone, benzene-toluene, liquid sodium-potassium). Most compounds are sparingly soluble (water-benzene, water-butyl alcohol, water-table salt), and many are slightly soluble or practically insoluble (water-BaSO 4, water-gasoline).

The solubility of a substance under given conditions is its concentration in a saturated solution. In such a solution, equilibrium is achieved between the solute and the solution. In the absence of equilibrium, a solution remains stable if the concentration of the solute is less than its solubility (unsaturated solution), or unstable if the solution contains a solute more than its solubility (supersaturated solution).

Numerous studies have shown that the factors that determine health are:

• biological (heredity, type of higher nervous activity, constitution, temperament, etc.);
• natural (climate, landscape, flora, fauna, etc.);
• state environment;
• socio-economic;
• level of healthcare development.

These factors influence people's lifestyle. It has also been established that lifestyle by about 50%, the state of the environment by 15-20%, heredity by 15-20% and healthcare (the activities of its organs and institutions) determine health (individual and public) by 10%.

Closely related to the concept of health is the idea of.

Health factors

WHO experts in the 80s of the 20th century determined the approximate ratio of various factors to ensure the health of modern people, highlighting four derivatives as the main ones. Subsequently, these conclusions were fundamentally confirmed in relation to our country as follows (WHO data in brackets):

• genetic factors - 15-20% (20%)
• environmental condition - 20 - 25% (20%)
• medical support - 10-15% (7 - 8%,)
• conditions and lifestyle of people - 50 - 55% (53 - 52%).

Table 1. Factors influencing human health

Sphere of influence of factors	Factors
	Health promoting	Impairing health
Genetic (15-20%)	Healthy heredity. Absence of morpho-functional prerequisites for the occurrence of diseases	Hereditary diseases and disorders. Hereditary predisposition to diseases
State of the environment (20-25%)	Good living and working conditions, favorable climatic and natural conditions, environmentally friendly habitat	Harmful living and production conditions, unfavorable climatic and natural conditions, violation of the environmental situation
Medical support (10-15%)	Medical screening, high level preventive measures, timely and comprehensive medical care	Lack of constant medical monitoring of health dynamics, low level of primary prevention, poor quality medical care
Conditions and lifestyle (50-55%)	Rational organization of life, sedentary lifestyle, adequate physical activity, social and psychological comfort. complete and rational nutrition, absence of bad habits, valeology education, etc.	Lack of a rational mode of life, migration processes, hypo- or hyperdynamia, social and psychological discomfort. unhealthy diet bad habits, insufficient level of valeological knowledge

Toxic substances enter the human body through the respiratory tract, gastrointestinal tract, and skin. When breathing, they enter the lungs, along with food - into the stomach. If they come into contact with the skin, poisons can have a local effect. Studying the influence chemicals The science of toxicology deals with the body, which classifies chemically harmful substances according to their toxic effect on humans and danger.
According to the toxic harmful effect, chemical substances are divided into:

• general toxic (hydrocarbons, alcohols, aniline, hydrogen sulfide, hydrocyanic acid and its salts, mercury salts, chlorinated hydrocarbons, carbon monoxide). These substances cause nervous system disorders, muscle cramps, disrupt the structure of enzymes, and affect the hematopoietic organs;
• irritants (organic dyes, antibiotics). These substances increase the body's sensitivity to diseases;
• carcinogenic (benzo(a)pyrene, asbestos, nitroazo compounds). They cause the development of all types of cancer. In this case, the disease process can be remote from the moment of exposure to chemicals for years and even decades;
• mutagenic (ethyleneamine, ethylene oxide, chlorinated hydrocarbons, lead compounds, mercury, etc.). The effects of these substances are detected late in life. When exposed to germ cells, the mutagenic effect affects the health of subsequent generations. The most common substances that affect reproductive function are boric acid and ammonia. They cause congenital malformations. In addition, the impact of mutagenic substances manifests itself in premature aging of the body, an increase in general morbidity, and the development of malignant neoplasms.

The toxic effect of chemicals is determined not only by their properties, but also by the amount of the substance entering the body (dose). For example, great value has a concentration of chemicals in the air working area, on which the dose directly depends.
Negative Impact harmful substances begins with a certain concentration in the body (threshold). Repeated exposure to a substance, even at a lower concentration, usually causes a greater effect than the previous one. The body's increased sensitivity to a substance is called sensitization. The resulting protein molecules that are foreign to humans and form antibodies can cause the development of allergic reactions.
In toxicology, indicators of the degree of toxicity (hazardousness of a substance) are used: the average lethal concentration when inhaled, ingested or in contact with the skin. Indicators of the degree of toxicity formed the basis for the development of MPC standards.
According to the classes of danger to humans, harmful substances are divided into 4 classes (Table 3.1). The fourth class includes the most hazardous substances.
Table 3.1
Extremely permissible concentration and the hazard class of some chemically harmful substances most often found in the working environment in railway transport

Name of substance (dust, aerosol)	MPC, mg/m3	Hazard class
Acetone	200	4
Gasoline fuel (in terms of carbon)	100	4
Kerosene, white spirit	300	4
Nickel (nickel oxides)	0,5	2
Carbon monoxide	20	4
Nitrogen oxides	5	2
Tantalum oxides	10	3
Dust containing more than 70% quartz	2	3
Glass and mineral fiber dust	3	4
Dust of animal origin	4	4
Sulfate anhydride	10	3

Workers involved in unloading bulk chemical cargo, cleaning and washing cars from residues of chemical cargo, degassing, and in violation of labor protection rules may experience chronic bronchitis, pneumonia, pneumosclerosis, heart disease, musculoskeletal system, gastrointestinal tract and neuroses. These workers' sense of smell is usually reduced. Workers involved in steaming crude oil tanks experience liver dysfunction and weakened immune responses of the body.

A person, throughout his life, experiences a number of factors that both positively and negatively affect his health. There are dozens of factors influencing human health. In addition to the genetic and biological characteristics of a person, environmental, social and physical factors also directly influence him. This affects not only a person’s health directly, but also their life expectancy.

The following factors usually influence a person:

• Physical
• Chemical
• Genetic
• Healthcare

Chemical factors

Factors affecting human health of this type of impact, as a rule, have a strong influence on the further existence of a person. Pollution of our atmosphere is directly related to the deterioration of health, and, consequently, life expectancy. This has always remained and will remain a pressing issue.

The most likely factors that accompany chemical poisoning or contamination are manufacturing enterprises, which release waste into the atmosphere, soil and water. As a rule, harmful substances enter the atmosphere - gases, which can have a direct effect on a person, that is, a person inhales harmful fumes along with the air, as well as a dual effect, that is, through water or land. Thus, when released into the soil, harmful substances can be absorbed by plants, which are then consumed by humans. The same goes for water. A person uses water for personal purposes, without even knowing what harmful substances it contains and what they pose as a threat. Since most gases emitted into the atmosphere can easily combine with water, areas with active industry have not only a polluted atmosphere, but also polluted water and soil.

Thus, the factors that shape human health are in this case cannot exceed pollution factors, and therefore in industrial areas children get sick more often and residents more often suffer from cancer, which significantly shortens their lives.

It is worth noting that the impact of polluted atmospheric air on the population, due to the following objective principles:

Variety of pollution - it is believed that a person who lives in an industrial area can be exposed to approximately several hundred thousand chemicals and toxic substances. In a certain area, a limited amount of harmful substances may be present, but in greater concentration, despite the fact that a combination of certain substances can cause an increase in their negative impact on humans.

Massive exposure - a person inhales approximately 20,000 liters of air per day, and even small concentrations of toxic substances contained in the air, comparable to such inhaled volumes, can cause a significant intake of toxins into the body.

Access of toxins into the internal environment of the body. As you know, the lungs have a surface area of ​​approximately 100 square meters, which allows them to absorb harmful substances and disperse them over a large surface of the organ. Toxins have direct contact with the blood, since from the lungs they immediately enter the systemic circulation, passing the toxicological barrier – the liver – on their way.

Difficulty of defense. Having refused to eat contaminated food or water, a person still continues to absorb toxins through the atmosphere and air.

Atmospheric pollution, as a rule, negatively affects the body's resistance, the consequence of which is increased morbidity and a number of physiological changes in the body. Factors affecting human health in this case reduce the average life expectancy.

If we compare atmospheric pollution, then it is tens of times more dangerous than water or soil pollution, since toxins directly enter the blood through the lungs.

The main soil pollutants are leaks of chemical waste, improperly buried or stored, the deposition of harmful substances from the atmosphere onto the soil, as well as the abundant use of chemicals in agriculture.

In Russia, the soil is contaminated with pesticides by almost 8%. At the moment, it is most likely that almost all water bodies are susceptible to anthropogenic pollution.

The factors influencing human health in chemical terms are so diverse that it is impossible to cope with them all. Since the scale of production is growing geometrically every day, and it takes tens, or even hundreds of years to restore natural resources.

Physical factors

The main physical factors that negatively affect a person are noise, electromagnetic radiation, vibration, and electric current.

Let's look at each type negative influence separately.

Noise is a complex of sounds and sounds that can cause disturbances or unpleasant sensations in the body, and in some cases even destruction of the hearing organs. So a noise of 35 dB can cause insomnia, a noise of 60 dB can irritate the nervous system, a noise of 90 dB causes weakening of hearing, depression, or, on the contrary, leads to excitation of the nervous system. Noise greater than 110 dB can lead to noise intoxication, which is expressed as alcohol intoxication, as well as to agitation and neurasthenia. The main sources of noise are transport, both road, rail, and aviation, as well as enterprises.

Vibration is an oscillatory process that can have a wide range of frequencies resulting from the action of some mechanism transmitted vibrational energy. This can be both transport and enterprises.

Electromagnetic radiation is usually transmitted by radio or television stations, radar installations, and various types of industrial devices. Chronic exposure to electromagnetic fields or radio waves can lead to changes in the nervous or endocrine system.

Genetic factor

As a rule, it is caused by the previous influence of toxic or polluting substances on previous generations of the population, which can ultimately result in hereditary diseases of descendants, and as a result - low life expectancy of certain parts of the population. Also, subsequent generations may be predisposed to certain diseases.

Healthcare

In many ways, everything depends on the development of the healthcare infrastructure in a particular country. Because the health status of the population and its life expectancy directly depend on this. The factors that determine human health are significant in this case. Take into account the general awareness of the population, the financing of medical structures, the development of innovative technologies and treatment methods, as well as timely diagnosis, which can only be successful with expensive equipment for manipulation.

Try to eat right, lead healthy image life and don't be nervous. From this, your life expectancy will increase by many years. Be healthy!