How diffusion occurs. Description of the physical phenomenon diffusion. The role of diffusion in everyday life and technology

Palm oil is a vegetable product made from the fruit of the oil palm. The birthplace of culture is Western Guinea. It is ideal for the manufacture of confectionery products intended for long-term storage. Interestingly, since 2015, the production of palm oil on an industrial scale has surpassed the production of other vegetable oils (sunflower, soybean, rapeseed) by 2.5 times. In terms of quantity, this is a record holder among food products, ahead of even fish oil. Does not contain .

Currently, the Swiss company Nestlé purchases more than 420,000 tons of palm oil per year for the manufacture of food products. The debate about its benefits and harms has not subsided so far. The abundance of carotenoids, the strongest, have a therapeutic effect on the human body. They reduce the likelihood of cancer, provide energy, participate in structuring bones, producing visual pigment retina, beneficial for joints and skin. The harm of the product is due to the high content of saturated fats, which are processed and remain in the form of slags. These refractory substances seal the intestines and blood vessels, increasing the risk of developing heart disease.

Varieties

Extracted from the fruit of the oil palm the following types oils: palm raw materials, palm kernel. This is the most common and cheapest product among vegetable fats. Because of this, it is widely used in food production.

At the present time, the oil palm is cultivated in South America, West Africa, Indonesia, Malaysia and Southeast Asia.

Crude oil is obtained by processing the pulp of the fruit, which contains up to 70%. Only the product that has gone through several stages of refining is suitable for food. Otherwise, crude oil is used only for technical purposes - for the manufacture of candles, soap and lubrication of spare parts.

Production principle

On the plantations, fruits are harvested, which are transported to the plant for further processing. The collected clusters are treated with dry hot steam to separate them. After that, the pulp of the fruit is pre-sterilized, then subjected to pressing. The resulting raw material is heated to 100 degrees and placed in a centrifuge to separate the liquid and impurities.

Stages of oil refining:

• elimination of mechanical impurities;
• hydration (extraction);
• neutralization (removal of free fatty acids);
• whitening;
• deodorization.

Palm kernel oil is a product obtained by extracting or pressing kernels from seeds. The degree of its digestibility is 97%.

Varieties of palm oil used in Food Industry:

1. Standard. Melts at a temperature of 36-39 degrees. Scope of application: baking and frying. In the process of cooking does not create smoke and burning. Foods prepared with standard palm oil should be consumed warm. Otherwise, the dish will harden and become covered with an unaesthetic film.
2. Olein. The melting point of the product is 16-24 degrees. Used for frying meat and dough. Has a creamy texture. Widely used in the cosmetic industry.
3. Stearin. It has the highest melting point among the three oils. It is 48-52 degrees. It is the hardest fraction of palm oil. Industries of application: cosmetology, metallurgy, food industry. Included in margarine.

A distinctive feature of palm oil from other vegetable oils is its solid consistency. The longer the product is stored, the higher its melting point becomes. So, for fresh palm oil, it is 27 degrees. And for a product with a weekly aging period, it increases to 42 degrees.

Butter is a source of fat-soluble vitamins A,. A freshly produced palm product has a light orange color due to the high content of beta-carotene. In the food industry, only decolorized oil is used. To do this, it is heated in an oven to 200 degrees, cooled. Under the influence of ultraviolet and oxygen, the natural dye beta-carotene is destroyed, as a result, palm oil becomes discolored, partially losing its value.

Chemical composition

100 ml of palm oil contains 884 kcal, while fat accounts for 99.7 g, and 0.1 g. Chemical composition The product is represented by vitamins E (33.1 mg), A (30 mg), (0.3 mg), K (0.008 mg) and (2 mg). The share is 100 mg. In addition, traces of lecithin, squalene and coenzyme Q10 were found.

According to the results of studies, it was found that the oil contains palmitic acid, which enhances the natural generation of cholesterol. As a result, the human body begins to intensively produce organic compound in an uncontrolled amount, which in turn increases the risk of blockage of blood vessels and the development of heart disease.

The World Health Organization strongly recommends reducing fatty acid intake. Dangerous foods include palm and butter, chocolate, meat, eggs. According to the European Food Safety Authority (EFSA), the maximum allowable intake of fatty acids is 10% of human energy consumption, including alcohol. In other words, with an oil of 884 kcal per 100 ml and a content of 44% palmitic acid in it, a safe daily dose of palm fruit pomace is 10 ml, provided there are no other sources of fatty acids in the diet.

Impact on the body of infants

Clinical studies have shown that infant formulas containing palm olein reduce absorption when compared to non-food formulas. And digestibility decreases from 57.4% to 37.5%.

In addition to lowering calcium absorption, stool fat loss increases. It becomes denser and less frequent.

Malabsorption of the macronutrient is due to the special location of palmitic acid relative to the palm olein fat molecule. Under normal conditions, it is in the lateral position. After starting the process of digestion of baby food in the intestines, it is split off, binding calcium in a free state. As a result, insoluble salts are formed: calcium palmitate. In fact, this is a soap that is not absorbed in the digestive tract, but is excreted in transit with the stool.

In order to avoid blocking the absorption of the mineral, the position of palmitic acid is artificially changed in olein. This product is called beta palmitate. As a result, structured oil with palmitic acid is in the central position in the composition of milk fat, does not break down, does not form soap with calcium, and is absorbed in the gastrointestinal tract unchanged.

Myths or reality

Palm oil is a product that causes a lot of controversy and misconceptions about its benefits and harms. Some argue that it is a natural source of tocopherols, beta-carotene, others insist that it is transformed into plasticine in the human body and clogs the intestinal patency. In addition, there is an opinion that raw materials for oil production are transported in oil tankers, as a result, it poses a threat to human health and causes cancer.

Let's consider the main guesses about oil and fat products, and whether they have a reasonable basis for existence.

Myth #1: "Palm oil contains dangerous trans fats"

It is not true. These compounds are not part of the product. What is the danger of trans fats? They replace beneficial fatty acids molecular level from cell membranes, disrupting the nutrition of cells and blocking. As a result, metabolic reactions slow down, which leads to the development of chronic diseases of the endocrine, digestive, cardiovascular, and genitourinary systems.

Myth No. 2 “For production, industrial palm oil is used, brought in tanks from oil products from Indonesia and Malaysia.

Lie. The raw materials used for the manufacture of butter must meet the requirements for food products, otherwise it is prohibited for use at the legislative level of the country. In addition, it is additionally cleaned, subjected to deodorization, as a result of which it loses its color, smell and taste.

Transportation stories are nothing more than an invention of competitors. For the transportation of palm oil, specially equipped tanks are used that meet all safety requirements. Before loading raw materials, tank containers are thoroughly cleaned (steamed, washed, dried) from the remnants of the previous product. In addition, it is forbidden to transport palm oil in containers that previously held non-edible, toxic cargo. Transportation of products is controlled by international organizations.

Myth #3: “Palm oil is of no value to the human body”

Wrong statement. It is a source of coenzyme Q10, carotenoids, tocotrients, tocopherols, polyunsaturated fatty acids (,), vitamins B4, F.

In the process of choosing oil for food purposes, remember that refined and deodorized products are free of impurities and partially devoid of nutrients. Therefore, it is recommended to give preference to unrefined species. Such oils should not be subjected to heat treatment, they are best used as a food additive to salads. These products include red palm oil. It fully retains all the useful properties listed above.

Myth #4 “Palm oil comes from the trunk of a palm tree”

This is an erroneous opinion. The product is obtained exclusively from the fruit of the oil palm by squeezing it out of the kernel or pulp. The main feature is a solid consistency from nature. Interestingly, the further south a tree grows, the more saturated fatty acids are contained in the fruits, and the further north, the more PUFAs. Because of this, the oil obtained in the southern tropical countries has a hard structure. This feature of the product provides desired shape prepared food and confectionery.

Myth No. 5 “Palm oil, when it enters the stomach, behaves like plasticine - it does not melt, but is a sticky mass that sticks to the body from the inside”

An absurd conclusion. When it enters the digestive tract, the product acquires the consistency of an emulsion. Palm oil is absorbed in the body in the same way as other foods. In moderate amounts (10 ml), it does not pose a risk to human health. According to postulates healthy eating The recommended norm of fats in the diet of an adult should not exceed 30% of the total amount of energy consumed. Of which MUFAs and PUFAs account for 6-10% each, saturated fatty acids - up to 10%.

Myth #6 “Manufacturers prefer palm oil because of the cheapness of raw materials”

Indeed it is true. The cheapness of the oil is due to the high productivity of the plantations of the main suppliers of raw materials (Indonesia and Malaysia). In addition, it is very technologically advanced. The solid structure of the product makes it attractive for use in the food industry (confectionery and bakery). Previously, liquid oils were used, which were hydrogenated to compact and harden. As a result, they accumulated dangerous trans fats and harmed the body. A modern alternative to them is palm oil. It is safe and of high quality by nature.

Myth #7 “Food products with palm oil are banned in developed countries”

It is not true. No country has banned palm oil. Moreover, he owns 58% of the consumption of vegetable fats in the world market.

health hazard

Palm oil is an essential ingredient in biscuits, sweets, chips, cheese, ice cream, and french fries. At the present time, it is difficult to find a product without this ingredient. However, the "passion" for overseas fat poses a danger to human health.

Harm of palm oil.

Is deposited in fat as quickly as possible

Although palm oil is of vegetable origin, it is similar in composition to animal triglycerides as it contains predominantly monounsaturated, saturated fatty acids. The most dangerous component of the product is palmitic acid, which causes diseases of the cardiovascular system. In addition, the oil accelerates the rate of deposition of fat in the "fat depot", which contributes to the rapid weight gain. , cheeses, ice cream, cream, chips, french fries, chocolate, sweets, cookies - products that already lead to weight problems, and they are further "enriched" with palmitic acid and palm oil.

Causes type II diabetes

Palmitic acid, which is part of the product, promotes the deposition of fat in internal organs and fabrics.

Causes addiction

Fatty acids "hit" the brain, as a result, the body's susceptibility to hormones that report satiety (insulin and leptin) decreases. Thus, he does not give a signal that you need to stop eating. Palmitic acid suppresses the ability of insulin and leptin to activate, which explains the dependence of a person on fatty foods.

Harms the liver

Palmitic acid is not completely eliminated from the human body. Accumulating in the pancreas, thymus, liver and skeletal muscles, it replaces healthy organ cells with fat. In addition, ceramides, which are part of palmitic acid, provoke the rupture of nerve cells and the occurrence of Alzheimer's disease.

Raises "bad" low-density lipoprotein cholesterol

With the regular intake of these compounds from the outside, they turn into biological "garbage" in the circulatory system. As a result, the immune cells of the body regard them as foreign bodies, which increases the risk of formation of atherosclerotic plaques in the vessels that are prone to rupture and the formation of blood clots.

Palm oil should not be used by persons over 50 years of age, children under 18 years of age, people with ailments of the digestive tract in the acute phase, osteopenia and osteoporosis, heart disease.

Remember, with regular intake of the product, fatty acids begin to accumulate in cell biomembranes. As a result, their transport functions are disrupted, which contributes to sexual dysfunction, the development of vascular and heart diseases. The most dangerous combination of palm oil with, which leads to obesity and atherosclerosis.

Beneficial features

Palm oil is one of the most affordable plant products, widely used in cosmetology, food industry and in the production of soaps, candles, powders, medicines. The latter, in turn, are aimed at eliminating problems with diseases of the gastrointestinal tract, blood vessels, heart, and eyes.

Characteristics of palm oil: reddish-reddish color, solid consistency, resistance to oxidation processes. The natural product exhibits pronounced antibacterial and wound-healing properties, prevents the occurrence of inflammatory reactions.

Palm oil health benefits:

1. Fights free radicals. It is the strongest antioxidant rich in carotenoids. Improves the condition of hair and skin. Prolongs youth, reduces the likelihood of developing cancer. In addition, antioxidants resist skin aging, slowing down age-related changes in the body.
2. Provides the body with energy due to its high fat content, fights fatigue syndrome, psycho-emotional disorders, improves memory, attention and mental capacity person.
3. Reduces the risk of blockage of blood vessels and the development of heart failure, stroke, heart attack, hypertension, atherosclerosis, coronary disease, respectively.
4. Improves the work of the vision analyzer (due to provitamin A), makes it possible to produce a pigment located in the retina and responsible for the visibility of the eye. Normalizes intraocular pressure, protects the cornea and lens, improves blood supply to the visual organ. It is used for the prevention and treatment of "night blindness", glaucoma, conjunctivitis, tired eye syndrome.
5. It prevents inflammation of the digestive organs, stimulates the secretion of bile, accelerates the healing of erosions on the mucous membrane of the stomach and intestines. Recommended for use by people suffering from colitis, gastritis, ulcers, cholecystitis, cholelithiasis.
6. Regulates the hormonal background in women, maintains normal estrogen levels, relieves inflammation of the ovaries, breasts, uterus (vitamins A, E). Used to relieve symptoms of premenstrual syndrome, menopause. For medicinal purposes, a palm oil tampon is inserted into the vagina to eliminate cervical erosion, vaginitis, and colpitis.

PUFAs, which are part of the oil, are involved in the structuring of the skeletal system, increase joint mobility.

With regular use of natural red palm oil, starting from the age of 30, osteoporosis, which in 60% of cases develops in women during menopause, and diseases of the musculoskeletal system can be avoided. Otherwise, a restructuring of the bone structure is observed, it becomes thinner, calcium is washed out, the mineral strength of the skeleton is lost, and fractures occur with minor loads. The main danger of osteoporosis is a slow but progressive disease, which as a result leads to vertebral injury, disability and even death among the elderly.

Application in traditional medicine

AT medicinal purposes they use red palm oil, which is high in provitamin A (carotenoids), which exhibit powerful antioxidant properties and neutralize saturated fatty acids (50%) in the product, which cause an increase in low-density lipoproteins in the blood. Useful properties: inhibits platelet aggregation, reduces the likelihood of heart attack and cataracts, lowers blood pressure, activates liver enzymes, reduces oxidative stress, scars stomach ulcers. The oil has neuro- and cardio-producing effects, nourishes the skin, heals the liver, prevents hypovitaminosis, and maintains visual acuity. The recommended daily intake of natural raw red palm oil for an adult is 10 ml. To avoid phosphorus-calcium metabolism, it is allowed to use it from 18 to 50 years. Do not heat treat.

Health Recipes:

1. In case of skin damage (from burns, cuts). Apply palm oil to the problem area twice a day for 14 days.
2. To relieve inflammation in oral cavity and treatment of periodontal disease. Soak a sterile gauze pad in oil, apply to the gums. Therapy is carried out for 2 weeks.
3. From cracked nipples. To heal wounds during breastfeeding, palm oil is heated in a water bath (for the purpose of disinfection), nipples are lubricated with it every time after the baby is applied to the breast. Repeat the procedure until the cracks heal.
4. From erosion of the cervix. From a sterile gauze pad or cotton wool, form a swab, soak in warm palm oil, and insert vaginally. The course of treatment is 10 days. The procedure is carried out one day after consulting a doctor.
5. For the treatment of lichen, eczema, psoriasis. Composition components: walnut oil (20 ml) and red palm fruit oil (80 ml), birch tar (3 g). Combine ingredients, mix. Apply the ointment 2 times a day for 2 weeks.
6. For diseases of the joints. To relieve the pain of gout, problem areas are massaged by rubbing the therapeutic composition. Ingredients of the ointment: 15 ml of palm, 25 ml of stone grape, 5 drops of lemon and pine, 10 drops of lavender oil. To relieve pain in arthritis, the joints are rubbed using the following composition: 5 drops of pine essential oil, 3 drops of lemon and lavender, 15 ml of olive and palm.

The greatest value for the human body is provided by the oil of the first cold pressing. It is characterized by a rich fatty acid composition and a low degree of oxidation. For eating and preparing medicinal recipes for external use, it is recommended to give preference to red palm oil with a maximum content of beta-carotene, which is 15 times higher than that of this substance in.

Application in cosmetology

The product, obtained from the fruits of the oil palm, has a strong softening effect, therefore it is recommended for the care of flaky, rough, dry and aging skin. In addition, manufacturers use it as a component to give a solid consistency to cosmetics. Palm oil tones, nourishes the dermis, increases its firmness and elasticity, smoothes shallow wrinkles, providing anti-aging properties.

Use in home cosmetology:

1. To moisturize the face. Mix palm oil in a ratio of 1: 1 with olive oil, apply to damp skin with patting movements. Apply the composition in courses for 2 weeks with a 10-day break.
2. For skin rejuvenation. Mix palm and apricot oils in equal proportions, apply to washed skin in the evening, for a quarter of an hour. Do not remove excess with a napkin, leave until completely absorbed. The procedure is carried out regularly for 14 days.
3. For hair nutrition. Apply the oil on the scalp and wet curls, leave for 1.5 hours, rinse thoroughly. Repeat the procedure twice a month. Remember, palm oil is poorly washed off the hair, so the mask is made before washing your hair.
4. To relax the body. Oil massage normalizes sleep, soothes, improves blood circulation, smoothes wrinkles.
5. To eliminate cellulite, geranium oil (7 drops) is mixed with palm (15 ml), olive (5 ml), lemon and dill (5 drops each), the resulting mixture is rubbed with massage movements into problem areas twice a day. In addition, during the period of struggle with orange peel, it is important to exercise, eat right and drink more than 2 liters of water per day.
6. For smoothing postoperative scars. Composition components: clove, mint (2 drops each), lavender, rosemary (4 drops each) and palm oil (15 ml). Apply to an uneven area 1-2 times a day for 10 days, then take a break for 1-2 weeks, resume the procedure.

Palm oil is a product that has a wide range of effects on the human body. It is used externally for body shaping, improving the condition of the skin and hair, relaxing the body, quenching pain in the joints, healing cracks and wounds. And inside to fortify the body with antioxidants A and E, lecithin and coenzyme Q10.

Conclusion

Palm oil is a useful and very expensive product until the multi-level purification of raw materials. After the strongest processing, it oxidizes, loses its nutritional value for the human body. Don't put your loved ones at risk. Introduce only uncooked red palm oil (maximum 10 ml per day) into your diet. Otherwise, palmitic acid, which is part of the product, worsens the mineralization of bones in children, disrupts metabolic processes, causes intoxication of the body, impairs the functioning of the brain, liver, and provokes the appearance of diabetes and obesity.

It is recommended to minimize or completely avoid the consumption of palm oil, which is included in fast food products (chips, french fries, fast foods, cheeseburgers), processed cheeses, yogurts, infant formula and confectionery. As part of this food, it is the strongest carcinogen that is dangerous to human health. In addition, children and adolescents under 18 years of age, as well as people over 50 years of age, should eat foods without palm oil, otherwise problems with phosphorus-calcium metabolism may occur.

In order not to fall into the "trap" of manufacturers, carefully read the label of the purchased product. Refuse to buy products that, according to the production technology, should contain only butter, but it has been replaced with palm oil or stearin. These include: cheese, ice cream, condensed milk, cream, cakes, cakes, cookies, sweets.

DIFFUSION(from Latin diffusio - spreading, spreading, scattering) - a non-equilibrium process caused by molecular thermal motion and leading to the establishment of an equilibrium distribution of concentrations within the phases. As a result of D., chemical alignment occurs. potentials of the mixture components. In a single-phase system with DC. temp-re and the absence of external. D. forces equalizes the concentration of each component of the phase throughout the volume of the entire system. If the temp-pa is not constant or the system is affected by external. forces, then as a result of D., a spatially non-uniform equilibrium distribution of the concentrations of each of the components is established (see Fig. Thermal diffusion, Electrodiffusion).

(2nd Fick's law). Mat. the theory of ur-tion D. coincides with the theory heat conduction equation.

For a mixture of components diffusion flux of each component j i, according to the thermodynamics of irreversible processes, is determined by the gradients of the chemical. potentials of all P mixture components:

where Lik- kinetic coefficient Onsager, which have a tensor character and proportional coefficients. D. components of the mixture (the index means that D. i-th component relative to k th). Chem gradients. potentials are taken at fixed. temp-re T. Expression (4) is a special case of Onsager's linear relations between thermodynamic. by the forces of D. and diffusion flows. According to Onsager's principle (cf. Onsager's theorem), in the absence of a magnet. fields .

Among the gradients of chem. potentials only n- 1 independent, they can be expressed in terms of concentration gradients using Gibbs - Duhem equations and represent the diffusion flux in the form

where Dik- tensor coefficient. D. Its diagonal elements determine the direct processes of D., while the off-diagonal elements determine cross-diffusion processes. Onsager relations for Dik are more complex than for Lik. For a binary mixture, the coefficient D 11 is associated with the coefficient. Onsager L 11 ratio

In the process of D., an increase in entropy occurs, and entropy production per unit time is:

If the mixture of components is affected by ext. strength Fk(for example, gravitational and inertial), then the phenomenon of D. changes significantly. Because the pressure gradient depends on external forces Fk, then the thermodynamic forces are not only chemical gradients. potentials, but also centrifugal force and gravitational force, and barodiffusion occurs. At the same time, the thermodynamic equilibrium corresponds to a stationary inhomogeneous distribution of concentrations. The D. process tends to establish this distribution. This process allows the determination of molecular weights from sedimentation in a centrifugal field in an ultracentrifuge.

Diffusion in solids. D. process in solids can be carried out with the help of several. mechanisms: exchange of places of atoms crystalline. structures with it vacancies, movement of atoms along interstices (see interstitial atom), simultaneous cyclic movement of several. atoms, the exchange of places of two neighboring atoms. In the formation of substitutional solid solutions, the exchange of positions of atoms and vacancies prevails.

Coef. D. in solids is very dependent on structural defects, increasing with an increase in their number. D. in solids is characterized by exponential. dependence on temperature with an activation energy greater than that of liquids. Coef. D. for zinc to copper increases 10-14 times with an increase in temperature from 30 o C to 300 o C.

microscopic The theory of atomic dislocation, based on the mechanism of jumps over vacancies, was developed by Ya. I. Frenkel. Substitution by a crystal atom. the structure of the vacancy is associated with the possibility of its transition through the potential. barrier. It is assumed that after the transition of an atom into a vacancy, due to its strong interaction with neighboring atoms, it has time to give up part of the energy before returning to its original place. The residence time of a given atom at a site adjacent to a vacancy is

where is the time of the order of the period of crystallized atoms. structures corresponding to the acoustic frequency. spectrum (~10 -13 s). Then the coefficient self-diffusion will have the form

where - activation energy, a- lattice constant, U is the energy of vacancy formation. For diff. gratings W do not differ very much (for example, for lead W 26 kcal/g*atom, for copper W 60 kcal / g * atom), and a and in f-le (12) can differ greatly. Coef. D. in solids can also be estimated using the Eyring theory of reaction rates, which also leads to exponential. depending on the temperature-ry with the activation energy. A similar theory was developed for D. in disordered substitutional alloys; it made it possible to take into account the effect of interstitial atoms on the self-diffusion of the metal, when D. is no longer described by a single exponent, since at sites with decomp. the configuration of atoms must be overcome diff. potent. barriers. In the case when D. goes through an exchange with vacancies or at the same time. moving around closed loop, and the coefficient D. component D1 and D2 different, there is a resulting flow of matter in the direction of matter with a large partial coefficient. D., proportional (Kirkendall effect).

The phenomenon of neutron transfer in condensers. environment, accompanied by multiple scattering, describes the kinetic. equation, which, generally speaking, does not reduce to the equation of D., however, the diffusion approximation is often useful when considering neutron diffusion.

At very low temp-pax in condensers. environments is possible quantum diffusion atoms, which is determined by the quantum sub-barrier tunneling motion of atoms, in contrast to the classical. D., which is determined by the above-barrier transitions of atoms. Creatures. The difference between quantum D. is that the coefficient. quantum D. is different from zero when the temperature tends to zero, its value is by many. orders more than the coefficient. classical D. at the same temp.

Other types of diffusions. Diffusion processes also include certain phenomena that are not associated with the transfer of particles. So, in optics, radiation takes place in an inhomogeneous medium during multiple processes of emission and absorption of photons, a cut called. radiation diffusion, however, this phenomenon is significantly different from the D. particles, since the balance equation for the photon flux density is described by the integral. ur-tion, a cut is not reduced to differential. ur-tion D. In spin systems in magn. field leveling process possible cf. magn. moment in space under the influence of spin-spin interaction - spin diffusion.

Lit .: 1) Groot S. de, Mazur P., Non-equilibrium, trans. from English, M., 1964, Ch. eleven; 2) Haase R., Thermodynamics of irreversible processes, trans. from German, M., 1967, ch. four; 3) Chapman S., Cowling T., Mathematical theory of inhomogeneous gases, trans. from English, M., 1960, Ch. 10, 14; 4) Ferziger J., Kaper G., Mathematical theory of transport processes in gases, trans. from English, M., 1976; 5) Ya. I. Frenkel, Kinetic theory of liquids. L., 1975; 6) Girshfelder J., Curtiss Ch., Byrd R., Molecular theory of gases and liquids, trans. from English, M., 1961, Ch. 9; 7) Gray P., Kinetic theory of transport phenomena in simple liquids, in: Physics of simple liquids. Statistical theory, trans. from English, M., 1971; 8) Smirnov A. A., Molecular-kinetic theory of metals, M., 1966, ch. eight; S) Andreev A. F., Lifshitz I. M., Quantum theory of defects in crystals, ZhETF, 1969, v. 56, p. 2057; 10) Kagan Yu., Klinger M. I., Theory of quantum diffusion of atoms in crystals, "J. Phys. C", 1974, v. 7, p. 2791; 11) Lifshits E. M., Pitaevsky L. P., Physical kinetics, M., 1979, p11, 12; 12) Landau L. D., Lifshitz E. M., Hydrodynamics, 3rd ed., M., 1986, p 59.

D. P. Zubarev.

Gazizova Guzel

"Steps into Science - 2016"

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Municipal budgetary educational institution

« Arskaya middle comprehensive school No. 7 "Arsky

Municipal district of the Republic of Tatarstan.

Republican scientific and practical conference

"Steps into Science - 2016"

Section: Physics and technical creativity

Research work

Topic: Observation of diffusion in water and the effect of temperature on the rate of diffusion.

Job title.

Gazizova Guzel Robertovna Zinnatullin Fidaris Faisalovich

7th grade student, physics teacher, 1st quarter. categories.

2016

1. Introduction Page 3

1. Research problem
2. Relevance of the topic and practical significance of the study
3. Object and subject of research
4. Targets and goals
5. Research hypothesis

1. Main part research work Page 5

1. Description of the place and conditions of observations and experiments
2. Research methodology, its validity
3. Main results of the experiment
4. Generalization and conclusions

1. Conclusion Page 6
2. References Page 7

Diffusion (Latin diffusio - spreading, spreading, scattering, interaction) is the process of mutual penetration of molecules or atoms of one substance between molecules or atoms of another, leading to spontaneous equalization of their concentrations throughout the occupied volume. In some situations, one of the substances already has an equal concentration and one speaks of the diffusion of one substance in another. In this case, the transfer of a substance occurs from an area with a high concentration to an area with a low concentration.

If water is carefully poured into a solution of copper sulphate, then a clear interface is formed between the two layers (copper sulphate is heavier than water). But in two days there will be a homogeneous liquid in the vessel. This happens completely randomly.

Another example is related to a solid body: if one end of the rod is heated, or electrically charged, heat spreads (or, respectively, electricity) from the hot (charged) part to the cold (uncharged) part. In the case of a metal rod, thermal diffusion develops rapidly, and the current flows almost instantly. If the rod is made of synthetic material, thermal diffusion is slow, and diffusion of electrically charged particles is very slow. Diffusion of molecules proceeds in general even more slowly. For example, if a piece of sugar is lowered to the bottom of a glass of water and the water is not stirred, it will take several weeks before the solution becomes homogeneous. Even slower is the diffusion of one solid into another. For example, if copper is covered with gold, then gold will diffuse into copper, but under normal conditions (room temperature and Atmosphere pressure) the gold-bearing layer will reach a thickness of several micrometers only after several thousand years.

The first quantitative description of diffusion processes was given by the German physiologist A. Fick in 1855.

Diffusion takes place in gases, liquids and solids, and both particles of foreign substances in them and their own particles can diffuse.

Diffusion in human life

Studying the phenomenon of diffusion, I came to the conclusion that it is thanks to this phenomenon that a person lives. After all, as you know, the air we breathe consists of a mixture of gases: nitrogen, oxygen, carbon dioxide and water vapor. It is located in the troposphere - in the lower layer of the atmosphere. If there were no diffusion processes, then our atmosphere would simply stratify under the action of gravity, which acts on all bodies located on the surface of the Earth or near it, including air molecules. At the bottom there would be a heavier layer of carbon dioxide, above it - oxygen, above - nitrogen and inert gases. But for normal life, we need oxygen, and not carbon dioxide. Diffusion also occurs in the human body itself. Human respiration and digestion is based on diffusion. If we talk about respiration, then at each moment of time in the blood vessels braiding the alveoli there is approximately 70 ml of blood, from which carbon dioxide diffuses into the alveoli, and oxygen diffuses in the opposite direction. The huge surface of the alveoli makes it possible to reduce the thickness of the layer of blood exchanging gases with the intraalveolar air to 1 micron, which makes it possible to saturate this amount of blood with oxygen and release it from excess carbon dioxide in less than 1 second.

This phenomenon also affects the human body - air oxygen penetrates into the blood capillaries of the lungs by diffusion through the walls of the alveoli, and then dissolving in them, it spreads throughout the body, enriching it with oxygen.

Diffusion is used in many technological processes: salting, sugar production (sugar beet shavings are washed with water, sugar molecules diffuse from the shavings into the solution), jam cooking, fabric dyeing, laundry, carburizing, welding and soldering of metals, including diffusion welding in vacuum (metals are welded that cannot be joined by other methods - steel with cast iron, silver with stainless steel, etc.) and diffusion metallization of products (surface saturation of steel products with aluminum, chromium, silicon), nitriding - saturation of the steel surface with nitrogen (steel becomes hard, wear-resistant), cementation - saturation of steel products with carbon, cyanidation - saturation of the steel surface with carbon and nitrogen.

As can be seen from the above examples, diffusion processes play a very important role in people's lives.

Problem: Why does diffusion proceed differently at different temperatures?

Relevance I see this study in the fact that the topic "Diffusion in liquid, solid and gaseous states" is vital not only for the course of physics. Knowledge of diffusion can be useful to me in Everyday life. This information will help you prepare for the physics exam for the basic and high school. I really liked the topic, and I decided to study it deeper.

The object of my researchis the diffusion that occurs in water at different temperatures, andsubject of study– observations by setting up experiments in various temperature modes.

Objective:

1. Expand knowledge about diffusion, its dependence on various factors.
2. Explain physical nature diffusion phenomena based on the molecular structure of matter.
3. Find out the dependence of the diffusion rate on temperature in miscible liquids.
4. Confirm theoretical facts with experimental results.
5. Summarize the knowledge gained and develop recommendations.

Research objectives:

1. Investigate the rate of diffusion in water at different temperatures.
2. Prove that the evaporation of a liquid is the result of the movement of molecules

Hypothesis: At high temperatures, the molecules move faster and because of this, they mix faster.

The main part of the research work

For my research, I took two glasses. He poured warm water into one and cold water into the other. At the same time, he dropped a bag of tea into them. Warm water turned brown faster than cold water. It is known that in warm water the molecules move faster, since their speed depends on temperature. This means that tea molecules will quickly penetrate between water molecules. In cold water, the speed of molecules is slow, so the phenomenon of diffusion here proceeds more slowly. The phenomenon of the penetration of molecules of one substance between the molecules of another is called diffusion.

Then I poured the same amount of water into two glasses. I left one glass on the table in the room, and put the other in the refrigerator. Five hours later I compared the water levels. It turned out that in a glass from the refrigerator, the level practically did not change. In the second - the level has decreased markedly. This is due to the movement of molecules. And it is greater, the higher the temperature. At a higher speed, water molecules, approaching the surface, “jump out”. This movement of molecules is called evaporation. Experience has shown that evaporation proceeds faster at higher temperatures, since the faster the molecules move, the more molecules fly away from the liquid at the same time. In cold water, the speed is low, so they remain in the glass.

Conclusion:

Based on the experiment and observations of diffusion in water at different temperatures, I was convinced that temperature strongly affects the speed of molecules. This was evidenced by the varying degrees of evaporation. Thus, the hotter the substance, the greater the speed of the molecules. The colder it is, the slower the speed of the molecules. Therefore, diffusion in liquids will proceed faster at high temperature.

Literature:

1. A.V. Peryshkin. Physics grade 7. M.: Bustard, 2011.
2. Library "First of September". M .: "First of September", 2002.
3. Biophysics at physics lessons. From work experience. M., "Enlightenment", 1984.

Table of contents of the subject "Electron Microscopy. Membrane.":

Factors affecting diffusion rate, merged into fica law. It states that the rate of diffusion is proportional to the following expression:

So, what molecules can pass through the membranes for diffusion count? Gases such as oxygen and carbon dioxide rapidly diffuse through membranes. Water molecules, although highly polarized, are small enough to slip between the hydrophobic phospholipid molecules without interference.

At the same time, ions and larger polar molecules with hydrophobic patches membranes are repelled, and therefore through the membrane is extremely slow. Other mechanisms are required for their entry into the cell.

Some ions and polar molecules enter the cell with the help of special transport proteins. These are channel proteins and carrier proteins. Water-filled hydrophilic channels, or pores, of these proteins have a strictly defined shape corresponding to one or another ion or molecule. Sometimes the channel passes not within one protein molecule, but between several neighboring molecules.

Diffusion channels flow in both directions. Such diffusion - with the help of transport proteins - is called facilitated diffusion. Transport proteins that carry ions are called ion channels. Typically, ion channels are equipped with "gates", that is, they can open and close. Ion channels that can open and close play an important role in the conduction of nerve impulses.

For protein channels shape is fixed. The disease known as cystic fibrosis has been shown to be the result of a defect in a protein that channels chloride ions. In carrier proteins, on the contrary, the shape undergoes rapid changes, up to 100 cycles per second. They exist in two states, and the mechanism of their action resembles a game of "ping-pong".

The figure shows how this mechanism works. Binders regions of the carrier protein in one state (“ping”) they are turned outward, and in the other (“pong”) they are turned inside the cell. The higher the concentration of dissolved molecules or ions, the more likely they are to be bound. If the concentration of the solute outside is higher than in the cell, as in the example of glucose in the figure, then the actual flow of this substance will be directed inward, and it will enter the cell.

This is how glucose enters the red blood cells. This kind of movement has everything characteristics diffusion, although it is facilitated by the participation of protein. Another example of facilitated diffusion is the movement of chloride and bicarbonate ions between erythrocytes and blood plasma during the so-called chloride shift. This is one of the mechanisms that provide partial and selective membrane permeability.

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• Participant: Holosha Darya Olegovna
• Head: Panova Lyudmila Valentinovna

The goal is to establish what determines the rate of diffusion in a liquid.

Diffusion experiments

Diffusion- a phenomenon in which there is a mutual penetration of molecules of one substance between the molecules of another (textbook definition).

Target- establish what determines the rate of diffusion in a liquid.

Diffusion is explained by the continuous movement of the molecules of a substance, the speed of movement depends on temperature. That's why hypothesis– the rate of diffusion in a liquid depends on the temperature.

Equipment: a glass of cold and hot water, potassium permanganate, spatula.

Safety: Handle hot water and glassware with care.

Description of the progress and results of the experiment.

1. Take two glasses of cold and hot water.
2. Using a spatula, pour potassium permanganate and observe the phenomenon.

Observing the phenomenon of diffusion in a glass of cold and hot water, I saw that the diffusion process proceeds faster in hot water than in cold water. The hypothesis was confirmed.

Overview of the application of the phenomenon under consideration in practice: the dependence of the diffusion rate on temperature is used in many technological processes: brewing tea or coffee, salting, cooking jam, dyeing fabrics, washing things.

The phenomenon of diffusion is based on the process of metallization - coating the surface of the product with a layer of metal or alloy to impart physical, chemical and mechanical properties to it. It is used to protect products from corrosion, wear, for decorative purposes. So, carburizing is used to increase the hardness and heat resistance of steel parts. Steel parts are placed in a box with graphite powder, which is installed in a thermal furnace. Due to diffusion, carbon atoms penetrate into the surface layer of the parts. The penetration depth depends on the temperature and the exposure time of the parts in the thermal furnace. It is also used in the smelting of many metals, such as steel.

Review of observations of the phenomenon under consideration in nature: plant nutrition, oxygen saturation of water, homogeneous composition of the atmosphere, physiological processes in the human body (respiration and digestion).

• The first quantitative description of diffusion processes was given by the German physiologist A. Fick in 1855.
• In 1638, Ambassador Vasily Starkov brought 4 pounds of dried leaves as a gift to Tsar Mikhail Fedorovich from the Mongolian Altyn Khan. Muscovites really liked this plant, and they still use it with pleasure. It was tea, the brewing process is diffusion.
• Diffusion is found not only in life, everyday life, but also in fairy tales, proverbs, sayings.

- The old Assyrian tale "King Zimaar": "The king had a smart adviser Ayaz, whom he respected very much. As usually happens in such cases, Ayaz had enemies who slandered him before the king, and he, having listened to them, imprisoned him. When his wife came to Ayaz, he told her to catch a big ant, tie a strong thread forty meters long to its paw, tie a rope of the same length to its free end and let the ant along the outer wall of the prison in the indicated place. As Ayaz said, so did the wife. Ayaz himself crumbled sugar on the window of the cell and the ant, by the smell of sugar, got to the cell where Ayaz was sitting. It was this phenomenon that saved Ayaz and helped the ant find the camera.

- Proverbs and sayings that can only be explained through knowledge of the phenomenon of diffusion.

1. A fly in the ointment.
2. Chopped onion smells and burns the eyes more
3. A vegetable shop doesn't need a sign.

Experiments on the force of friction

The experience is described in the textbook A.V. Peryshkin "Physics 7 cells": a textbook for educational institutions/ A. V. Peryshkin. – M.: Bustard, 2012.

When one body comes into contact with another, an interaction occurs that prevents their relative movement, which is called friction. And the force characterizing this interaction is called the friction force. (from textbook)

There are three types of friction: static friction, sliding friction, rolling friction.

In UMK Peryshkina A.V. only the dependence of the friction force on the weight of the body is investigated, we have added experiments that are mentioned indirectly (dependence on the surface area, on the type of rubbing surfaces).

Target- find out what the force of sliding friction depends on.

Equipment: wooden block, dynamometer, set of weights, sandpaper, guide rail.

Hypothesis. The force of friction depends on the area of ​​contact of the surface, on the weight of the body, on the type of contacting surfaces.

: be careful with the equipment.

1. Place a wooden block on the guide rail.
2. Attach a dynamometer to the bar and pull it evenly. The dynamometer will show the traction force, equal to strength friction. Write down the result.

F tr = 0.3N

1. Turn the bar to the other side and measure the dynamometer readings.

F tr = 0.3N

Conclusion: the force of sliding friction does not depend on the area of ​​contact between the bodies.

1. Measure the force of sliding friction with one weight and two weights.

F tr = 0.3N

F tr = 0.5N (1 load)

F tr = 0.6 N (2 weights)

Conclusion: the greater the force that presses the body to the surface (body weight), the greater the resulting friction force.

1. Measure the force of sliding friction with one load on sandpaper.

F tr = 0.3N

F tr \u003d 0.6 N (on sandpaper)

Conclusion: the friction force depends on the kind of contacting surfaces (surface roughness)

: without rest friction, neither people nor animals could walk on the ground, since when walking, the legs are repulsed from the ground. During icy conditions, there is little friction between the sole of the shoe and the ground, it is very difficult to push off the ground and the feet slip. To increase the frictional force between the sole of the shoe and the ice, sidewalks are sprinkled with sand. Friction provides fastening of various materials, parts of tools, various devices, structures. Due to the friction between the threads, fabrics do not spread, hammers, axes, shovels and other tools are held on the handles. Bolts with nuts, nails, screws, wedges, fasten parts of structures by friction. Friction helps a person hold objects in their hands. Without the friction of the bow against the strings, it would be impossible to play the violin or cello.

Many plants and animals have various organs that serve for grasping (the antennae of plants, the trunk of an elephant, the tenacious tails of climbing animals). All of them have a rough surface to increase the friction force.

Among living organisms, adaptations are common (wool, bristles, scales, spikes located obliquely to the surface), due to which friction is small when moving in one direction and large when moving in the opposite direction. The movement is based on this principle. earthworm. The bristles, directed backwards, freely pass the body of the worm forward, but inhibit the reverse movement. With elongation of the body, the head part moves forward, while the tail part remains in place, with a contraction, the head part is delayed, and the tail part is pulled up to it.

Significant friction is essential for the working surfaces of the organs of motion. Necessary condition movement is a reliable adhesion between the moving body and the support. Grip is achieved either by points on the limbs, or by small irregularities, for example, bristles, scales, tubercles. Significant friction is also required for the grasping organs. Their shape is interesting: these are either tongs that capture the object from two sides, or strands that envelop it. The hand combines the action of forceps and full coverage from all sides; the soft skin of the palm adheres well to the roughness of objects that need to be held.

The presence of interesting facts about the phenomenon under consideration:

• Leonardo da Vinci (1519) was the first to formulate the laws of friction. He argued that the friction force arising from the contact of a body with the surface of another body is proportional to the load (pressing force), directed against the direction of motion and does not depend on the contact area. Leonardo's model was rediscovered 180 years later by G. Amonton and received its final formulation in the works of Sh.O. Coulomb (1781). Amonton and Coulomb introduced the concept of the coefficient of friction as the ratio of the friction force to the load, giving it the value physical constant, which completely determines the friction force for any pair of contacting materials.
• The nature of the friction force is electromagnetic. This means that the cause of its occurrence is the interaction forces between the particles that make up the substance. The second reason for the friction force is the surface roughness. The protruding parts of the surfaces touch each other and prevent the movement of the body. That is why, for movement on smooth (polished) surfaces, less force is required than for movement on rough ones.
• Proverbs and sayings: (collected by students).

1. If you don’t grease, you won’t go;
2. Things went like clockwork;
3. You can't hold an eel in your hands;
4. Mow the scythe while the dew; down with the dew, and we are home;
5. A woman from a cart is easier for a mare;

• The lowest coefficient of friction for solid body(0.02) has Teflon. Everyone has it modern man there are pots and pans with non-stick Teflon coating in the kitchen.

Experiments on thermal conductivity

The experience is described in the textbook A.V. Peryshkin “Physics 8th grade”: a textbook for educational institutions / A.V. Peryshkin. – M.: Bustard, 2012.

Thermal conductivity- the phenomenon of the transfer of internal energy from one part of the body to another or from one body to another during their direct contact. (from textbook)

All metals have a different structure, so they must transfer heat in different ways.

Putting forward a hypothesis. The thermal conductivity of different metals should be different.

Target- observe the thermal conductivity of metals.

Equipment: aluminum and brass rods, plasticine, needles, a candle, matches, two tripods.

Description and observance of safety precautions during the pilot study : observe safety precautions when working with a candle.

Description of the progress and results of the experiment:

1. Attach with plasticine needles on the rods.
2. Attach the rods to the tripod.
3. Light a candle and heat the rods.
4. Observe the needles on the rod.

Observations showed that the needles from the aluminum rod began to fall off faster than from the brass one.

Conclusion: the thermal conductivity of different metals is not the same.

Overview of the application of the phenomenon under consideration in practice: Often during the heat treatment of the product, it is necessary to maintain high temperature Therefore, metals are used in the kitchen, as their thermal conductivity and strength are higher than those of other materials. For hot tea, in order not to burn yourself, choosing between a metal or porcelain cup, you need to choose a porcelain one.

Pots, pans, baking sheets, and other utensils are made of metal. A good example of the use of materials with high thermal conductivity in the kitchen is the stove. For example, electric stove burners are made of metal to ensure good heat transfer from the hot coil of the heating element to the pot or pan.

People use materials with low thermal conductivity between hands and utensils to avoid getting burned. The handles of many pots are made of plastic, and the trays are removed from the oven with oven mitts made of cloth or plastic with low thermal conductivity. Copper has good thermal conductivity and is used in soldering irons.

Overview of observations of the phenomenon in question in nature: snow protects winter crops from freezing; air, ice, snow, fat are poor conductors of heat - this saves the lives of many animals that live in forests and water environments (black grouse sleeps in winter, burying its head in the snow). In winter, water bodies are covered with ice, which prevents their further freezing, many representatives of aquatic fauna survive.

The presence of interesting facts about the phenomenon under consideration:

• Jean Baptiste Joseph Fourier introduced the concept of "thermal conductivity".
• Great difficulties for the builders of buildings are delivered by the subsidence of the foundation, especially in regions with permafrost. Houses often crack due to the thawing of the soil beneath them. The foundation transfers some amount of heat to the soil. Therefore, buildings began to be built on piles. In this case, heat is transferred only by thermal conductivity from the foundation to the pile and further from the pile to the ground. What should piles be made of? It turns out that piles made of durable solid material must be filled with kerosene inside. In summer, the pile conducts heat from top to bottom poorly, because. liquid has low thermal conductivity. In winter, due to the convection of the liquid inside the pile, on the contrary, it will contribute to additional cooling of the soil. Such a project has actually been developed and tested!
• Italian scientists have invented a shirt that allows you to maintain a constant body temperature. Scientists promise that it will not be hot in summer and cold in winter, because it is made of special materials. Similar materials are already used in space flights.
• In the old machine guns "Maxim" heating water protected the weapon from melting.
• The phenomenon described below demonstrates the property of metals to conduct heat well.

If you make a mesh of wire, providing a good metal connection at the places where the wire crosses, and place it above the gas burner, then you can ignite the gas above the mesh when the valve is turned on, while it will not burn under the mesh. And if you ignite the gas under the grid, then the fire “will not leak” up through the grid!

In those days, when there were no electric miner's light bulbs, they used the Davy lamp.

It was a candle "planted" in a metal cage. And even if the shaft was filled with flammable gases, the Davy lamp was safe and did not cause an explosion - the flame did not go beyond the lamp, thanks to the metal mesh.