A box of qualitative problems in the physics of construction of matter, molecules, diffusion. Marine style and marine fragrances in perfumery

Black Sea. It would seem so familiar and absolutely safe. Nothing like this. In its waters, not only poisonous marine life awaits you, but there is a more serious threat - suffocating poisonous fumes.

Dead zone

Not everyone knows that 90% of the Black Sea waters are saturated with hydrogen sulfide. This discovery was made back in 1890 by the Russian geologist Nikolai Andrusov. In some places, the hydrogen sulfide layer is located at a distance of 50 meters from the sea surface, and it constantly continues to strive upward. Periodically, a liquid lens of "dead" water approaches very close to the surface layers, which has a detrimental effect on the inhabitants of the underwater world.

However, there is still life in the hydrogen sulfide cloud, although in the absence of oxygen, only certain types of marine worms and anaerobic bacteria can exist here, which are involved in the decomposition of the remains of living organisms.

Hydrogen sulfide in water is not a unique phenomenon; it is also found in other seas and oceans. But given that the Black Sea is actually isolated from the World Ocean by the shallow Bosphorus and there is practically no normal water exchange, the concentration of hydrogen sulfide here is off scale.

Sometimes, as a result of storms, hydrogen sulfide vapors break out, and then in the gas outlet zone there is a specific smell of rotten eggs. This is extremely dangerous. On contact a large number hydrogen sulfide with air can explode. According to experts, the explosion of all hydrogen sulfide contained in the Black Sea can be compared with the consequences of the fall of an asteroid weighing half the mass of the moon.

But something like that already happened. In the dead of night September 12, 1927 Crimean peninsula experienced the full power of an 8-magnitude earthquake. The epicenter lay 25 kilometers away south of Yalta, giant landslides were recorded, almost the entire crop died, many buildings were destroyed.

As eyewitnesses testified, the vibrations of the earth's surface were accompanied by a disgusting stench and flashes that soared from the surface of the sea to the sky. Pillars of fire, shrouded in smoke, reached several hundred meters in height. So the Black Sea burned. Most scientists have no doubt that hydrogen sulfide was to blame.

Experts are seriously puzzled by the problem of hydrogen sulfide accumulating in the surface layers of the Black Sea. Any tectonic shift can lead to the release of a huge amount of toxic substances, and then the consequences can be much more serious than during the Crimean earthquake.

Oceanologist Alexander Gorodnitsky is convinced that such a threat is quite real: "The Black Sea is a seismically active region, there are earthquakes that provoke the release of gas hydrates - accumulations of methane and other combustible gases compressed under high pressure."

In an unfavorable scenario, tons of concentrated sulfuric acid will enter the atmosphere: thousands of people will die from suffocation, millions will have to move away from the coast, but even there they will be overtaken by hydrogen sulfide, spilling acid rain.

A few years ago, a hydrogen sulfide release was recorded at the Koblevo resort in the Nikolaev region (Ukraine). At that time, more than 100 tons of dead fish turned out to be on the shore. Engineer Gennady Bugrin, who participated in the aftermath of the disaster, warns that such an emergency could happen again at any time and on a larger scale.

Toxic water

The situation with the ecological situation in the waters of the Black Sea is no better, primarily because of the constantly incoming waste from the Danube, Prut and Dnieper. Industrial enterprises and public utilities without a twinge of conscience pour tons of production and human waste into rivers, which leads to the gradual extinction of many species of flora and fauna of the Black Sea coastal waters. In Russia, the most polluted maritime zone is located in the area of ​​the ports of Novorossiysk and Taman.

Together with river water, pesticides, heavy metals, phosphorus, nitrogen enter the Black Sea, as a result of which phytoplankton rapidly reproduces and the water begins to bloom. And this leads to the destruction of bottom microorganisms, which in turn causes hypoxia and the subsequent death of many inhabitants of the seabed - squid, mussels, oysters, young sturgeon, crabs. According to environmentalists, the kill area sometimes exceeds 40 thousand square meters. km.

Of course, all this does not pass without a trace for a person. Head of the department of extreme natural phenomena Oleg Stepanyan, Candidate of Biological Sciences, warns and reminds that the Black Sea is not a pool with filtered water and you need to choose the right places for swimming, because often even on city beaches you can see how sewage is poured into the sea from nearby cafes and eateries.

And although, according to Stepanyan, special services monitor the cleanliness of the beaches, the bacterial situation on them, it is important to be vigilant. Especially dangerous in such cases are sandy and pebble beaches big resort towns, where the process of self-purification of water is slowed down.

Deputy coordinator of the public organization "Environmental Watch for North Caucasus» Dmitry Shevchenko notes that there are so polluted areas in the Black Sea, for example, in the Gelendzhik or Anapa bays that it is simply risky for health to enter the water.

Today, the massive development of green filamentous and lamellar algae, including the so-called sea lettuce (Ulva), has become a constant problem for the Black Sea. Eating such algae is fraught with serious poisoning, since they grow in places overflowing with organic substances coming through sewage.

Doctors also warn about the possible harm to the body of mussels and rapans caught in the large port waters of Novorossiysk, Tuapse, and Sevastopol. Mussels actively filter poisoned sea water, and rapans are predators that eat them. But if, nevertheless, someone decides to feast on Black Sea delicacies, then one should pay attention to the color of their meat. Light yellow or pinkish indicates, most likely, its suitability for eating, but blue, black or just very bright indicates that the molluscs have accumulated heavy metals, oil hydrocarbons and other toxicants.

Dangerous inhabitants

In the waters of the Black Sea, of course, there are not as many poisonous inhabitants as in tropical seas, but still, extreme caution must be exercised here. First of all, we are talking about large jellyfish with a diameter exceeding 30 centimeters. In no case should they be touched, as you can get burned from stinging cells. A "kiss" of such a jellyfish in the throat or chest area can cause respiratory paralysis or heart failure.

In the sandy shallow waters of the Anapa bank, in the area from the village of Volna to the village of Blagoveshchensky, a stingray is often found, the poisonous spike of which can pierce even a thick rubber coating and inflict a very sensitive wound, followed by swelling of the damaged part of the body.

A small scorpion fish, or, as it is also called, sea ruff, is also a serious danger. She mainly hunts among the rocks, and hypothetically, she can be stepped on. A prick of its poisonous thorns will be very painful and it will take several weeks to heal the wound.

The sea dragon, although it does not look intimidating, carries no less of a threat than a stingray or scorpionfish. Poison glands are located on its first dorsal fin. Fishermen or divers sometimes inadvertently grab a thorn, and as a result, excruciating sharp pains in the wound area and a feverish state, accompanied by a rise in temperature. In this case, it will not be possible to do without a doctor.

The work of a poet, the dialectic of a philosopher, the art of a researcher -
these are the materials that make up a great scientist.
Kliment Arkadyevich Timiryazev
Kliment Arkadyevich Timiryazev(06/03/1843 - 04/28/1920) - Russian naturalist, physiologist - the founder of the Russian
and British scientific schools of plant physiologists, historian of science.

BOX OF QUALITATIVE TASKS IN PHYSICS
STRUCTURE OF A SUBSTANCE, MOLECULES, DIFFUSION

Didactic materials in physics for students, as well as their parents ;-) and, of course, for creative teachers. For those who love to learn! Your attention 40 quality tasks in physics on the topic: "Structure of matter, molecules, diffusion". We will accompany the tasks with cognitive notes and comments - for the curious, we will give some tasks detailed answers;-) And ... according to the tradition of green pages, let's treat ourselves masterpieces of world art…

Task #1
Who was the first to experimentally discover the motion of molecules?

Answer: In 1827 a British botanist Robert Brown, examining pollen from his flowers under a microscope, he found that pollen grains floating in water move continuously and randomly. Brown was a real scientist and, faced with the incomprehensible, conscientiously investigated an open phenomenon. He found that particles move faster in hot water than in cold water. I was convinced that their path was absolutely random and did not depend on London cabs rumbling along the pavement ...

Task #2
Why and how does the Brownian motion of suspended particles depend on their size?

Answer: Even Robert Brown noticed that very small particles suspended in a liquid, observed in a microscope, are in a state of continuous random movement and the smaller the particle, the more intensively it moves. The reason for Brownian motion is precisely established: continuously and chaotically moving liquid molecules hit grains of a solid body from all sides and set them in random motion. The smaller the mass of the grain, the faster it moves, and vice versa. Thus, the Brownian motion of grains is due to the motion of liquid molecules.

Robert Brown(Robert Brown; 1773-1858) - British botanist, morphologist and systematizer of plants. All his life, Robert Brown was sure that his mark will remain in history thanks to botanical merit. But... it's hardly the only one botanist, firmly established in the history of physics.
Stephen Pierce(Stephen Pearce; 11/16/1819 - 01/31/1904) - British portrait painter.

Task #3
If we look at a drop of highly diluted milk under a microscope, we can see that small drops of oil floating in the liquid are constantly moving. Explain this phenomenon. Why does their movement accelerate when the temperature of milk rises?

Answer: Because the molecules of a liquid move continuously and randomly, and with increasing temperature, the speed of their movement increases.

Task #4
In which medium at the same temperature does Brownian motion occur more intensely in a drop of water or in a drop of oil?

Answer: In water, as a less viscous medium.

Task #5
How to explain the spread of smells of gasoline, perfume, varnish and other odorous substances in the air?

Answer: The smell of odorous substances usually spreads due to convection; in a completely calm atmosphere, the spread of odors is due to diffusion associated with the random movement of molecules.

Task #6
"Old Woman Izergil", 1895, Maxim Gorky
Maksim Gorky(03/28/1868 - 06/18/1936) - Russian writer, prose writer, playwright. One of the most significant and famous Russian writers and thinkers in the world.
“... The air was saturated the pungent smell of the sea and the greasy fumes of the earth, shortly before evening, abundantly moistened with rain. Even now fragments of clouds roamed the sky, lush, of strange shapes and colors, here - soft, like puffs of smoke, gray and ash-blue, there - sharp, like fragments of rocks, dull black or brown ... "
How many different memories, vivid unforgettable emotions, many of us have associated with the sea! With what to compare a special unique smell of the sea? And what explanation from the point of view of physics can you make?

Aivazovsky Ivan Konstantinovich(Hovhannes Ayvazyan; 07/29/1817 - 05/02/1900) - the world-famous Russian marine painter, battle painter, collector, philanthropist.

For the curious: Water constantly evaporates from the surface of the seas and oceans. Together with it, annually enters the atmosphere several hundred thousand tons of iodine, some boric acid, phosphates and obviously other chemicals. During strong winds the clear boundary between the sea surface and the atmosphere is destroyed. The wind, along with spray and foam, carries away salt, humus, detritus, which then partially fall out on land and ... together with iodine take part in the creation inimitable symphony of the smell of the sea... And they conduct this magic orchestra convection And diffusion.

§ sea ​​color and the color of the sea wave on the green page "Journey through the green", as well as shades of green in colors and numbers ;-)
§ Placer seascapes V moonlight Ivan Konstantinovich Aivazovsky on the green page "The Moon in Painting" and ... some interesting details about the apparent size of the Moon ;-)

Task #7
If a certain amount of odorous and volatile liquid is spilled at one end of the room, then in a few seconds its smell will be felt at the other end of the room. Doesn't this fact contradict the fact that average speed gas molecules at room temperature more speed bullets and is several hundred meters per second?

Task #8
What is the difference between the movement of the same molecule in air and in vacuum?

Answer: In a vacuum, a molecule moves uniformly and in a straight line. In the air, due to collisions with other molecules, the same molecule moves along a broken zigzag line with varying speed.

Task #9
If you mix equal volumes of mercury and water, and then alcohol and water, then in the first case you get twice the volume of the mixture, and in the second - less than twice the volume. Why?

Answer: Molecules of alcohol and water mutually penetrate into the spaces between them and enter into chemical interaction. As a result, the volume of the mixture of water and alcohol is less than the sum of the initial volumes.

Task #10
Why are gases more easily compressible than solids and liquids?

Task #11
Oil, placed in a strong steel cylinder and subjected to enormous pressure of tens of thousands of atmospheres, comes out through the walls of the cylinder. What does this experience say?

Answer: Experience indicates the presence of intermolecular gaps in the substance of the cylinder walls - the distance between iron atoms in the crystal lattice of steel over size oil molecules.

Task #12
Are hot and cold water molecules and ice molecules the same size and composition?

Task #13
Why is diffusion faster in gases and liquids than in solids?

Task #14
What physical processes play a leading role in the survival of a scion to a wild tree?

Peter Mörk Mönsted(Peder Mork Monsted; 10.12.1859–20.06.1941) - Danish painter, a recognized master of landscape, a representative of the "golden age" of Danish painting.

Task #15
Explain on what phenomenon the foliar feeding of seedlings and fruit trees is based by spraying their leaves.

Answer: On the phenomenon of diffusion. Diffusion exchange through the surface of plant leaves performs the function of not only respiration, but, in part, nutrition. You can supplement the answer to this question with the words of the great Russian physiologist Kliment Arkadyevich Timiryazev from his monumental work "Plant Life" published in 1898. “Whether we talk about the nutrition of the root due to substances found in the soil, whether we talk about the air nutrition of the leaves due to the atmosphere, or the nutrition of one organ due to another, neighboring one, everywhere we will resort to the same reasons for explanation: diffusion».

Task #16
What phenomenon is the salting of vegetables, mushrooms, fish and other products based on?

Georg Flegel(Georg Flegel; 1566-1638) - German painter, founder of the German school of still life.

Task #17
What phenomenon is the soaking of salted herring based on? Explain how salt passes from herring to water.

Answer: The soaking of salted herring is based on the phenomenon of diffusion. Salt molecules in solution decompose into ions, and ions, as a result of the diffusion process, move into water, exchanging places with water ions.

Task #18
In order for cucumbers to remain lightly salted for a long time, brine with cucumbers must be stored in a cold room - a cellar or refrigerator. Why?

Task #19
Dry oak barrels, in which they intend to pickle cucumbers, are first dipped for some time in a vat of hot water, after which the slots in the barrels disappear. Explain physical essence this procedure.

Task #20
"Three men in a boat, not counting the dog", 1889, Jerome Klapka Jerome
Translation from English by Mikhail Alexandrovich Salier
“... Among other things, George suggested taking eggs and ham for the first breakfast, which are easy to prepare, cold meat, tea, bread and butter and jam. For lunch, he recommended biscuits, cold meats, bread and butter, and jam, but no cheese. Cheese, like kerosene, imagines too much of itself. He wants to take over the whole boat for himself. It penetrates through the basket and gives everything a taste of cheese. You don't know what you're eating - apple pie, sausages, or strawberries and cream. Everything looks like cheese to you. Cheese has too much smell…”
By what physical phenomenon can cheese "take over the whole boat"? However, I didn’t notice such violent activity behind Russian and Adyghe cheese in the refrigerator, but such predatory behavior is very common for fish dishes and seafood ;-) and therefore they must be stored in an airtight container, and even better in a separate section of the refrigerator.

For the curious: Distinctive feature of many varieties of cheese are their aromas, sometimes so extravagant that an unprepared and inexperienced person with cheese delights can be knocked down and brought to a semi-conscious state ... However, the most interesting thing is that the most smelly and disgusting looking cheeses have such a charming taste that it is better to describe it poems ... The most famous description of the aromas of a cheese shop can be found in the novel Belly of Paris by Emile Zola.

CHEESE SHOP

Edward Jean Dambre(Edward-Jean Dambourgez; 11/14/1844 - 01/15/1931) - French painter, engraver.

THE GREAT AND TERRIBLE CHEESE SYMPHONY

The Belly of Paris, 1873, Emile Zola
Translation from French by Nadezhda Markovna Gnedina
“... Cheeses stank around them. On both shelves along the back wall stretched huge mounds of oil; Breton butter bulged out of the baskets; covered with linen, blocks of Normandy bulged, like sculptural studies of bellies, wrapped in wet rags; other, open lumps of butter, which with the help of wide knives were shaped into pointed cliffs, cut into hollows and cracks, were exactly weathered Mountain peaks , gilded by a pale autumn sunset. The chalky whiteness of the eggs in the baskets under the red, gray-veined marble of the counter completed the picture; cheeses called "plugs" stacked top to top in boxes of straw, and Gurney cheeses, flat as medals, merged into darker stripes tinged with greenish tones. But most of all, cheeses accumulated on the counter. Here, next to a pound of butter wrapped in beet leaves, is a huge cantal cheese, like an ax cut; further followed: the head of a golden chester, the head of a Swiss one, like a wheel that had fallen off a barbarian's chariot; round Dutch cheeses that looked like severed heads with gore spattered; they seem hard as skulls, which is why Dutch cheese is called "dead head". Parmesan, wormed between the piles of this cheese mass, added its own flavor to it. The three heads of brie, lying on round planks, had the melancholy faces of fading moons; two of them, already very dry, were full moons; and the third was the moon on the wane, it melted, flowing out a white sludge that formed a puddle, and threatened to demolish the thin planks with which they tried in vain to restrain its onslaught. Porsalu, similar to antique discs, were branded with the name of the manufacturer. Romantur, in a silver foil dress, looked like a piece of nougat or sweet cheese, accidentally caught in the midst of this caustic fermenting mass. And the Roqueforts under glass caps, the Roqueforts also strove to seem noble gentlemen; their faces were unclean and fat, speckled with blue and yellow veins, like those of the rich, sick with a shameful disease from excessive addiction to truffles; the hard, greyish goat curds that lay on the platter beside him and were the size of a child's fist resembled the pebbles that roll from under the hooves of the leader goat as he rushes ahead of the herd along a winding mountain path. Then the most seasoned cheeses entered the general choir: pale-yellow mondors, reeking of a sweetish rotten cheese; sharper, very thick trois with rumpled sides, which added to the general stench the mustiness of a damp cellar; Camembert, smelling of stale game, Neuchâtel, Limburg, Marolsche cheeses, Ponleveques, square and fetid - and the peculiar smell of each of them burst into a sharp note in the nauseating melody of stench; there were also livaros, dyed red, which made the throat tingle, as from the fumes of sulphurous acid; and, finally, at the very top there was an olive, covered with hazel leaves, just like peasants throw branches on carrion on the edge of the field, decomposing in the sun. The cheeses melted from the midday heat; the mildew on their rind melted, glossed, shimmering in magnificent coppery reds and greenish-blues, like badly healed wounds; and the warm wind stirred the fallen skin of the olive under the leaves, and it heaved slowly and heavily, like the chest of a sleeping man; a wave of life penetrated one of the livaros, and it gave birth to a bunch of worms that crawled out of a gap that was blurred in it. And jerome cheese with anise, resting in its thin box behind the scales, stank so much that flies fell all around on red marble with gray veins ... "

Task #21
Why does cream in milk settle faster in a cold room than in a warm one?

Answer: At low temperatures, fat particles are less affected by the surrounding molecules, since their speed of movement is less, they easily “stick together”, being attracted to each other.

Task #22
Why should a dark-colored wet cloth not be left on long time in contact with white cloth?

Answer: The dye molecules diffuse onto the white fabric and color it.

Task #23
Throw a crystal of potassium permanganate into the water. After a while, a purple cloud forms around it. Explain the phenomenon.

Answer: The substance, dissolving, diffuses in water, coloring it purple.

Task #24
In a moment of danger, some cephalopods throw out an “ink bomb” in front of the open mouth of a predator - a jet of dark-colored liquid. The ink spreads in the water in a thick cloud, and under the cover of a “smoke screen”, the mollusk more or less safely escapes, leaving the enemy to wander in the dark. Why, after a while, the space filled with this liquid becomes transparent even in calm water?

Cephalopods: flock of squid(Ommastrephes sloaneipacificus); octopus(Octopus vulgaris); Russia(Rossia glaucopis); cuttlefish(Sepia officinalis).
Kondakov Nikolai Nikolaevich(1908-1999) - Russian animal painter, zoologist and traveler.

For the curious:“... The ink of cephalopods contains an organic dye from the melanin group, similar in composition to the pigment that dyes our hair. The shade of ink is not the same for all cephalopods: for cuttlefish it is blue-black (in a strong dilution of the “sepia” color), for octopuses it is black, for squids it is brown. The ink is produced by a special organ - the pear-shaped outgrowth of the rectum. It's called an ink bag. Not all contents of the ink sac are ejected at once. An ordinary octopus can put a "smoke screen" six times in a row, and after half an hour it completely restores all the spent ink. The coloring power of the ink liquid is unusually great. In five seconds, a cuttlefish paints all the water in a tank with a capacity of 5.5 thousand liters with ejected ink. And giant squids spew so much inky liquid that sea water becomes cloudy for hundreds of meters!
"Class Cephalopoda (Cephalopoda)", 1968,
Igor Ivanovich Akimushkin

Task #25
Why does the smoke from a fire, as it rises, cease to be visible even in calm weather?

Answer: Smoke particles and air molecules mix through convection and diffusion. At the same time, the concentration of smoke particles continuously decreases and it becomes invisible.

Task #26
Baby air balloons usually filled with helium. Why do they lose their elasticity in a day, shrink and stop rising?

Answer: Helium diffuses through the shell of the balloon.

Problem #27
The water of rivers, lakes, and other bodies of water contains molecules of gases that are part of the air. Due to what phenomenon do these molecules get into the water? Why do they penetrate to the bottom of the reservoir? Describe how air is mixed with water?

For the curious: Diffusion processes play an important role in the supply of oxygen to natural water bodies. Oxygen enters the deeper layers of water in stagnant waters due to diffusion through their free surface. Therefore, any restrictions are undesirable. free surface water. So, for example, leaves or duckweed covering the surface of the water can completely block the access of oxygen to the water and lead to the death of its inhabitants. For the same reason, narrow-necked vessels are unsuitable for use as an aquarium.

Volkov Efim Efimovich(03/23/1844 – 02/17/1920) - Russian painter - landscape painter, member of the Association of Traveling Art Exhibitions, full member and academician of the Imperial Academy of Arts.

Polenov Vasily Dmitrievich(06/01/1844 - 07/18/1927) - Russian artist, master of historical, landscape and genre painting, teacher.

Task #28
Under what processes and how does diffusion occur in humans and animals? Prepare a detailed message on this topic.

Problem #29
Inhalation is a method of drug administration based on the inhalation of gas, vapor or smoke. Inhalation can be natural, for example, in salt caves, at seaside resorts or in the forest (inhalation of phytoncides) and artificial, using special spray devices - inhalers. What physical phenomenon is this method of drug administration based on? And what are phytoncides?

For the curious: Phytoncides are biologically active volatile substances formed by plants that kill or inhibit the growth and development of bacteria, microscopic fungi, protozoa ... Hectare pine forest emits about 5 kilograms of volatile phytoncides into the atmosphere per day, and juniper forest - about 30 kilograms! Pine phytoncides are detrimental to Koch's bacillus, the causative agent of tuberculosis; fir phytoncides kill pertussis; birch phytoncides affect the microbe of Staphylococcus aureus ...

Shishkin Ivan Ivanovich(01/25/1832–03/20/1898) - Russian landscape painter, academician, professor, head of the landscape workshop of the Imperial Academy of Arts, one of the founding members of the Association of Traveling Art Exhibitions.

§ Painting "Morning in a pine forest" on the green page of The Seasons: Spring. A hidden corner of a dense pine forest performed by Ivan Ivanovich Shishkin and the bear family performed by Konstantin Apollonovich Savitsky.

Task #30
Explain the phenomenon of the steel carburizing process - obtaining a hard hardened "crust" on the surface of a mild steel product.

Answer: When steel products are calcined in a mixture of coal and various salts, carbon atoms diffuse into surface layer metal. This improves the strength of the product.

Task #31
In technology, the method of cold "welding" of metals is used. To do this, they impose one iron part on another, compress them strongly and get a very strong connection. What happens in the process of cold "welding" of metals?

Answer: With strong compression, the surfaces of the products soften, accompanied by mutual diffusion of particles, the cohesive forces become so significant that they provide a strong connection of the products.

Task #32
What is the process of dyeing solids with dyes?

Task #33
Why is chalk written on the blackboard and not a piece white marble? What can be said about the interaction between the particles of these substances? Why don't chalk particles fall off the surface of the board?

Answer: The attractive forces between chalk molecules are weaker than between marble molecules, and when we write with chalk on a blackboard, the chalk particles peel off and remain on the board, being held on it due to intermolecular cohesion forces.

Bogdanov-Belsky Nikolai Petrovich(December 8, 1868–February 19, 1945) was a Russian itinerant artist, academician of painting.

Problem #34
To reduce the friction force between the contacting surfaces, they are ground and polished. However, after careful polishing, the friction force begins to increase again. Explain the reason for this phenomenon.

Answer: The forces of intermolecular cohesion increase.

Problem #35
To tightly close the glass bottle, they use ground stoppers, for example, bottles with expensive perfumes. The cork and part of the neck of the vial are polished smoothly in the place where they are in contact. What is the basis for the use of ground stoppers?

Problem #36
What explains why dust does not fall even from a downward facing surface?

Answer: Dust particles are held on the surface by the force of mutual attraction of molecules.

Problem #37
Why, when folding polished glass, do they put paper strips between them?

Answer: So that the glasses do not stick together under the action of the forces of mutual attraction of molecules.

Problem #38
Why is it impossible to combine two wooden rulers into one, tightly attaching them to each other?

Answer: Due to the roughness of the surfaces of the rulers applied to each other, a small number of points of contact are formed, where the forces of molecular attraction are manifested.

Problem #39
The most important factor in the formation of karst caves is the diffusion of carbon dioxide from the air into the water. For the formation of a cave, a sufficient amount of water precipitation and a successful form of relief are necessary. There are karst caves only where it occurs: limestone, dolomite, chalk, as well as gypsum and rock salt. Why?

Answer: Limestone, dolomite, chalk, gypsum and rock salt are rocks that are easily eroded by water. Limestone is very poorly soluble in pure distilled water. Its solubility increases several times if dissolved carbon dioxide is present in water, and it is always present in natural water thanks to diffusion. However, even at the same time, limestone is slightly soluble in water compared to gypsum or salt. But ..., this has a positive effect on the formation of extended karst caves, since gypsum and salt caves not only quickly formed, but also quickly destroyed.

Carl Hasch(Carl Hasch; 11/08/1834–01/04/1897) was an Austrian landscape painter.

For the curious: By eroding rocks, water not only carries their particles outward, forming voids, it creates luxurious cave decorations: stalactites, stalagmites, stalagnates... They arise as a result of precipitation of calcium carbonate when carbon dioxide is removed from the water saturated with it. Stalactites and stalagmites grow in layers, in the section they show concentric patterns, like annual rings on trees. The shape and name of these formations depend on how the water flows.
stalactites(from the Greek stalaktós - flowing drop by drop) - drip-drop formations hanging in the form of icicles, tubes, combs, fringe from the cave ceiling.
stalagmites(from the Greek stálagma - drop) - sagging-drop formations, columnar, conical shape, rising from the bottom of the cave.
Stalactites and stalagmites are, in a sense, twin brothers :-) almost every stalactite grows a stalagmite. They grow towards each other and eventually merge, forming a column - stalagnate.

§ Several photographs from the Big Azish Cave on the green page “Photo Album: “Adygea”, summer 2005” - stalactites: “Angel Wings”, stalagmites: “Priest with retinue”, stalagnates: “Tree of Happiness” and “Palm of desires”.

Task #40
On the Nature of Things, Titus Lucretius Car
Titus Lucretius Car(Titus Lucretius Carus; c. 99 BC - 55 BC) was a Roman poet and philosopher. It is considered one of the brightest adherents of atomistic materialism, according to which sensually perceived (material) things consist of chemically indivisible particles - atoms.
“... And, finally, on the seashore, breaking the waves,
The dress is always damp, but hanging in the sun, it dries;
However, it is impossible to see how moisture settles on it,
And you can’t see how she disappears from the heat.
This means that water is crushed into such tiny parts,
That they are completely inaccessible to our eyes.
So is the ring from the inside, that for a long time on the finger
Worn, from year to year it becomes thinner and thinner;
Drop by drop hammers, falling, a rock; curved
The plow's iron coulter is imperceptibly erased in the soil;
And the pavement of roads, paved with stones, we see
Erased by the feet of the crowd; and the right hands of the statues
Bronze near the gates of the city are gradually losing weight
From falling to them the people passing by.
It is obvious to us that a thing becomes smaller from erasure,
But the separation of the bodies leaving it every moment,
Nature jealously forbade our eyes to see…»
How can you comment on this passage from the point of view of modern physics? Although the existence of molecules and atoms was established long ago and even their sizes were determined, until recently it was not possible to consider individual molecules. Only in 1945 Alexander Alekseevich Lebedev using an "electron microscope", which allows you to examine objects of very small sizes, was able to photograph some large protein molecules (albumin). What is the magnification modern models electron microscopes, which can significantly expand the possibilities of science and production? Prepare a detailed message on this topic.

Lebedev Alexander Alekseevich(11/27/1893–03/15/1969) - Russian, Soviet physicist, specialist in the field of applied and electronic optics, atmospheric optics and hydro-optics, laser technology, the theory of the glassy state, the study of the properties and structure of glasses, cosmic radiation.

§ Seven more quality problems on the topic "Brownian motion. Diffusion" on the green page “Casket of qualitative problems in physics “hodgepodge” :-) The casket consists of four thematic blocks: 1) Brownian motion. Diffusion; 2) Atmospheric pressure; 3) Properties of the liquid. Archimedean force; 4) Thermal phenomena.

I wish you success in your decision
quality problems in physics!

Literature:
§ Katz Ts.B. Biophysics at physics lessons

§ Lukashik V.I. Physics Olympiad
Moscow: Enlightenment publishing house, 1987
§ Tarasov L.V. Physics in nature
Moscow: Enlightenment publishing house, 1988
§ Perelman Ya.I. Do you know physics?
Domodedovo: VAP publishing house, 1994
§ Zolotov V.A. Questions and tasks in physics grade 6-7
Moscow: Enlightenment publishing house, 1971
§ Tulchinsky M.E. Qualitative problems in physics
Moscow: Enlightenment publishing house, 1972
§ Kirillova I.G. Book for reading in physics grade 6-7
Moscow: Enlightenment publishing house, 1978
§ Erdavletov S.R., Rutkovsky O.O. Entertaining geography Kazakhstan
Alma-Ata: Mektep publishing house, 1989.

New Eau de Toilette Giorgio Armani is “water of joy and delight”, if its name is translated from Italian. Another and can not be sea water! In this fragrance, the sweetness of fruits and fragrant floral notes are mixed with her smell, which, combined together, bring a feeling of harmony with nature.

• Top notes: lemon, black currant, pear, violet leaves
• Heart notes: peony and jasmine
• Base notes: cedar, cashmere, cane sugar

Popular

Wood Sage & Sea Salt by Jo Malone

A light taste of sea salt, which even the air is saturated with, and dry, crumbly sand - this is what combines the new Wood Sage & Sea Salt composition. Perfumer Christine Nagel conceived it in such a way that it conveys a feeling of freedom and enjoyment of nature - after all, this is what you feel when you find yourself in front of the endless sea horizon?

• Notes: ambrette, sea salt, sage, seaweed, grapefruit

Fragrance Summer Sailing Clean

Imagine a picture of stunning beauty: you are floating on the ocean at the most impressive time of day - the time of sunset, when the sky is painted in incredible shades. Admiring the sky, you feel the breath of a fresh breeze, splashes of sea waves pour on your skin. We bet that you would not mind "bottling up" all these sensations and storing them in a small bottle, opening it from time to time, awakening memories in yourself and reviving them. Such a bottle, by the way, exists - the perfume brand Clean filled it with a refreshing salty-sea scent and called it Summer Sailing.

• Top notes: Sicilian bergamot, cucumber peel, aldehydes
• Heart notes: "fresh air after the storm" accord, violet leaves
• Base notes: sea moss, white woods, musk

Beach Walk fragrance from the Replica series, Maison Martin Margiela

“Sun-kissed salty skin” is the description the creators of Beach Walk picked up for the fragrance. The combination of citrus notes will remind you of the freshness of the sea wind, musk - of warm, sun-warmed skin, coconut notes - of how pleasant it is to enjoy exotic fruits on the shore.

• Top notes: bergamot, lemon
• Heart notes: heliotrope, ylang-ylang, coconut milk
• Base notes: musk, pink pepper

Fragrance Salt Air, Demeter

Impression fragrances are certainly interesting and unusual, but if you would like a perfume that smells like pure sea air, pay attention to Demeter's Salt Air. Thanks to him, the sea breeze will be on your dressing table.

• Notes: salt and sea water

Fiji Lotus fragrance, The Body Shop

At a time when the stress of life in the stone jungle reaches its limit and the only thing you want is to be in some paradise land alone with itself, you must save the new fragrance "Lotus Fiji". A few drops of it combine everything that you may miss on days filled with routine everyday worries: the warmth of the sun, the freshness of the breeze, the tenderness of the surf. The aroma will take you to a place where it seemed no human has set foot, and nature lives on its own.

The smell of the sea is specific, unique, it has no "earthly" analogues. Neither flowers, nor herbs, nor needles, nor any other plants or substances smell like this. The carriers of the smell of the sea, as scientists believe, are numerous organic and inorganic substances, which are primarily plant microorganisms. Aromatic compounds with amazingly pleasant odors, delicate and subtle, reminiscent of the smell of the sea, have recently been isolated from them in the department of physiology of algae of the Institute of Hydrobiology of the Academy of Sciences of the Ukrainian SSR. They are extracted from marine microscopic algae (phytoplankton), do not require special fixatives, like ambergris and other fixing substances, as they have a fairly persistent smell. On their basis, new perfumes are being developed.

Why does foam form on the sea surface?

In sea water, especially in the coastal part, there are a lot of suspended particles of various origins, including dead organic substances that form the surface film. With strong wind waves, the film foams and white flakes appear. When the excitement subsides, they again spread over the surface of the water in the form of a film. But, if there are a lot of dead organic substances in the shells of gas bubbles, then it can remain on the surface of a calm sea for a long time.

Flakes of foam on a calm sea and on a beach are a sign of the presence in the water of a large number of various organic compounds, microelements, some of which have biologically active properties. It has been established, for example, that sea ​​foam promotes growth and the development of not only algae and marine animals, but also land plants, including crops. At the same time, much depends on its concentration: a three percent solution inhibits growth, and a more liquid one stimulates it. Wheat, barley and corn treated with this solution ripen faster, grain quality improves. Curious practical results sea ​​foam obtained by Estonian farmers: in the fields near Gulf of Finland the yield of early cabbage doubled, barley grain became fuller and of better quality.

Some scientists consider surface layer of sea water nursery of life. No wonder in Greek mythology there is a legend that phrodite, personifying the goddess of love, beauty and fertility, was born from sea foam.

Currently, biologists are deciphering the complex chemical composition of sea foam and exploring the possibilities of using its beneficial properties in medicine and agriculture.

What are the benefits of night swimming?

In July and August, the water is usually warmer than the air in the evenings, and you don’t want to leave it. It is especially pleasant to fall in the dark without bathing suits - this creates an extraordinary lightness, a feeling of merging with a gigantic, calm sea. Diving, you see neither the bottom nor the surface, you feel like a small grain of sand immersed in the abyss, as if flying away into the Universe. The sea glows with millions of highlights and the moonlight path illuminates your path to the shore.

Why swim in the sea healthier than in a river or lake?

According to materialistic theory, life originated in the ocean and is impossible without water. in one liter black sea ​​water 17-18 g of salts are dissolved; eat in this water trace elements, biostimulants, vitamins, hormones. Having come out on land, all living organisms retained blood in their bodies - a liquid that carries nutrients, oxygen, carbon dioxide - that is, blood performs the same function as ocean water where the first living creatures on the planet once lived.
The water of the seas and oceans contains salts necessary for man. Penetrating through the skin, salts have healing effect on the whole body. For example, iodine ions are important for cures for atherosclerosis, bronchitis, bronchial asthma, pneumonia and metabolism and. Bromine ions contained in sea water are very useful for the treatment of neurosis, hypertension. insomnia. Thanks to the evening and night swimming in the sea, the nervous system of a person calms down and he falls asleep well and sleep soundly at night.
similar to human blood. Dissolved in sea water ions Na, Ca, Mg, K, Br, I that remain on the skin after swimming in the sea, these are a kind of intradermal "injection" of salts,improves skin elasticity, reduces skin laxity and her swelling. Each bath can be called a nourishing mask for the whole body.

In the water of the Black Sea there are almost all the elements of the periodic table, but most of all in our sea of ​​table salt ( sodium chloride) and bitter salt (magnesium sulfate). They define it the taste of sea water., its mineralization is 17.6 g/l. Thanks to great content salt in the sea, it is easier to swim in salty sea water than in fresh river water. Is it necessary to take a shower after swimming in the sea? Remaining on the skin after bathing, sea salt ions continue to have a beneficial effect on the human body. If you do not pour yourself after swimming in the sea fresh water, then you will lengthen the time of the healing effect of sea water on your body. After swimming in the sea, it is better not to immediately wash off the sea salt, but to wash with soap every 2-3 days.