Cognitive-experimental lesson in the preparatory group “Secrets of salt water.
Today we will talk about the positive and negative properties of table salt.
We sprinkle salt on bread, fill it with soup, first and second courses, add it to cereals. Salt for us is just a seasoning that improves and enhances the taste of food. I assure you that more than half of the inhabitants of the planet do not think about the fact that salt should be limited and used in doses, not to refuse, but to adhere to the norms, pour from the heart what they call, according to the principle "the main thing is to taste delicious."
But it's not so simple! Salt is not only a seasoning, salt is a medicine in the literal sense, and in the same literal sense it can be poison.
Let's start with the bad. Harm of salt
Main and proven harm:
Hypertension, edema, metabolic disorders, osteoporosis, weakening of the walls of blood vessels, kidney stones - this is just a modest list of dangerous conditions that can cause the intake of excess salt.
Consuming a large number of salt, a person drinks a lot, the amount of fluid in the body increases, blood volume increases and it thickens, the heart begins to work harder (tachycardia, arrhythmia), pressure rises, edema appears, fatty plaques are deposited on the walls of blood vessels, which contributes to the development of heart attacks, strokes.
Sodium chloride (the same salt) with excessive consumption, it reduces bone density, is deposited in the joints in the form of salt deposits, calcium is washed out of the body, which disrupts the delivery of minerals and other necessary substances to the joints, with age Negative consequences salt intake can lead to osteoporosis.
Due to an excess of salt and water retention, the muscles respond poorly to impulses: “By retaining water, excess salt stretches the muscle fibers, weakens and destroys them, it also affects their contraction. If you do not delve into the complex jungle of anatomy, it is worth knowing that the activity of the sodium-potassium pump and the passage channels in the nerves is regulated to excite the muscle. Due to an overabundance of elements, this process can be disrupted and the muscles respond poorly to impulses.
Excess salt contributes to excessive accumulation of protein in the kidneys and even the formation of stones., “can cause kidney failure, nephritis, canal inflammation and other unpleasant symptoms. This is due to the fact that the kidneys must work several times more in order to filter back into the body as much water as possible, to excrete deposits of excess salt and toxic ammonia.
Salt with impurities, including simply poisonous ones, takes most shelves in supermarkets. And not every manufacturer will write that the salt contains not only salt itself, but also, for example: potassium ferrocyanide (E536 in the European food additive coding system; non-toxic complex salt) as an anti-caking agent.
In addition - salt, even without impurities, mostly stone table salt, of low quality. Even salt sold under the guise of Himalayan pink may not be Himalayan at all, but embellished with dyes.
The most optimal in quality from the medium-low price category of salts - sea and iodized, not cheap. But you need to be careful with the latter: its excessive consumption can lead not only to an excess of salt, but also to an excess of iodine. Sea salt is rich in minerals that are absent in rock salt - potassium, iodine, magnesium, calcium. If you normally use sea salt, it is much more useful than table salt and it has much less negative consequences.
“According to the World Health Organization, the systematic intake of excess salt compared to the physiological norm leads to an increase in blood pressure and, as a result, to a variety of diseases of the heart and kidneys, stomach cancer and osteoporosis.
Along with other sodium salts, table salt can cause eye diseases and eyelid edema - salt retains water in the body, a large volume of which "stores" adipose tissue. May lead to an increase in intraocular pressure and the development of cataracts.
For example, there is evidence that in Finland the number of heart attacks and strokes has decreased by 80% due to the fact that salt intake has been reduced by a third. This of course suggests that salt can be harmful, but it says more that salt should be limited, not excluded.
IN moderate amount salt has a positive effect on the psyche, the nervous system - it is a natural stimulant of taste buds, is involved in the production of endorphins - hormones of happiness. However, in abundance it can also become a drug.
The constant intake of high doses of salt leads to metabolic disorders, to the development of hypertension, hormonal disorders.
In general, everyone uses salt, a rare person does not salt food at all (which is no less fraught than when he overdoes it) - and this product, so popular, seemingly safe, does not cause people any special questions in terms of its harm. However, salt is indeed a kind of drug, no matter what quality it is.
Packaged, five-minute food, chips, fast food, fried - salt mixed with fat and harmful substances, sausages, beer delicacies, crackers - all this taught the people in abundance to overconsumption salt when taste sensations ceases to be aware of the amount of salt consumed.
A person often doesn’t even think about it, doesn’t count every day how many grams of salt he ate, doesn’t count a person and the amount of salt, in addition to pure salt, which is contained together with impurities, preservatives, nitrates in purchased products, and, for example, 4 slices of bread is already 1 grams of salt, in 100 grams of cheese, on average, as much as 8-10 grams of salt, even more in sausage, there is a lot of salt even in cucumbers and tomatoes.
And the constant oversalting of food is not only “planting” the body on a certain dose of salt, which is expressed in both psychological and physiological habit - after all taste buds over time, from an excess of salt, they become dull and require more and more salt for taste - a person already ceases to receive satisfaction from saturation with food if it is slightly less salted. Endorphins are produced, the taste of food is acutely felt, despite pressure surges and swelling - there is a temporary euphoria.
How can you really not call salt a drug?
The benefits of salt
In fact, salt brings more benefit than harm. It is very easy to understand this: it is enough to imagine what would happen if there were no salt, we would lose much more than we gained. There is only one correct approach to the use of salt: it is necessary to dose its use in a normalized manner and choose the safest options (high-quality salt).
Healthiest types of salt: Pink Hawaiian salt (pink brown, expensive, useful product), pink and black Himalayan salt (also contain minerals), black Thursday salt with charcoal (used in Japan). But such salt will not be sold in a shop on the corner, and if you notice it there, you should doubt its authenticity.
The norm of salt intake for an adult who does not suffer from serious diseases in which it is worth limiting the amount of salt is up to 5 grams per day per day. clean look e. That is, the consumption rate (the most extreme limit) both in pure and sublimated form is about 5 grams per day, given that the person is healthy and does not suffer from hypertension, diabetes mellitus and other serious ailments.
There are experts who recommend reducing salt intake to 2 grams and even to 0.5 grams. If we also take into account the fact that we get about 10-15-20 grams with food, in ready-made food products, which we buy - we usually overeat the salt of the norm several times, which is fraught.
Salt cannot be replaced by anything, as they say, “If salt loses its taste, then what can make it salty again? She is no longer fit for anything, all that remains is to throw her out, under the feet of people ”(Bible, New Testament). Without salt, food not only would not have a rich and pronounced taste, but many products would not be able to be stored: pickles, smoked, preparations for the winter, for example.
More than 90% of water on earth is salty, marine, oceanic. In a liter of such water, on average, 30-40 grams of salt. That is, the salty environment is the natural environment for the Earth. True, after drinking a liter of sea water, a person will exceed the norm of salt consumption by three times (!!). Man needs fresh water.
Saline, which is sometimes used as a blood substitute, contains sodium chloride, not without reason, according to the experience of "tried", the blood tastes salty. Salt is necessary for the normal functioning of organs and body systems, as well as water. If a person can still live without sugar, replacing glucose with fructose and other options, then salt cannot be replaced by anything and it is useful in moderate doses.
Salt is not poison! Salt can be a medicine, but it can be harmful, like everything else, if you use it indefatigably. Even if the most healing medicine drinking in buckets will not do you any good, let alone when people oversalt their food and then blame the salt for their troubles.
If a person does not consume salt, all body systems will begin to fail, and, as doctors assure, the body will begin to break down slowly: the immune system will “sit down”, it will slow down nervous system, dizzy, etc.
"The chlorine ion in salt is the main material for the production of hydrochloric acid - important component gastric juice.
Sodium ions, together with ions of other elements, are involved in the transfer nerve impulses, contraction of muscle fibers, therefore, their insufficient concentration in the body leads to general weakness, increased fatigue and other neuromuscular disorders.
Of course, it is better to use high-quality salt. Bad salt can not only spoil the taste of the dish (for example, there is salt with additives that seem to be unsalted or leave a strange aftertaste), but also harm the body if used constantly.
There is even visiting therapy salt rooms- halochamber. The essence of therapy is that a person inhales "salty" air, which is akin to inhalation. Basically, such procedures are recommended for people with respiratory problems, but in sanatoriums they are “prescribed” to everyone as tonic. According to statistics, after a course of visits to the halochamber, the condition of patients suffering from lung diseases improves by more than 70%, and fatigue and depression syndrome have even more indicators of positive dynamics.
“Salt aerosol is a complex of halite, sylvin and carnallite, which make up about 98% of the total volume of the substance, that is, its main minerals are potassium chloride, magnesium and sodium. Potassium chloride helps to restore the contractile function of the heart and strengthen the body's defenses.
Well, now, perhaps, about one of the most important qualities of salt, if you use it externally - healing. Salt is useful in baths, it removes toxins, has a positive effect on the whole body and skin, some, using it in a mixture with soda, filling the bath with this solution, manage to lose weight.
Salt can replace antibiotics for external infected wounds. During the Great Patriotic War, some doctors (due to the lack of worthwhile medicines and because they just used inexpensive, but effective means) used lotions, compresses with saline solution for the treatment and healing of wounds.
From the nurse's story: “On the vast surface of the contaminated wound, the doctor applied a loose, abundantly moistened with saline large napkin. After 3-4 days, the wound became clean, pink, the temperature, if it was high, dropped almost to normal levels, after which a plaster cast was applied. After another 3-4 days, the wounded were sent to the rear. The hypertonic solution worked great - we had almost no mortality."
I will say that even now doctors who are not chasing sales of expensive drugs for the sake of the pharmaceutical business prescribe gauze dressings, baths with salt for inflamed wounds, and this helps a lot. Salt is antiseptic and draws out everything "bad" from the area on which the bandage is applied. Gargle with salt, wash the nose with a cold.
It turns out you can walk on water! In Turkey there is a salt lake on which they walk on foot in summer. Salt covers its surface like a crust of ice.
And swimming beetles can run on water. But that's a completely different story...
Let's get back to salt. You can arrange a small salt lake at home.
Let's do an experiment. For this we need 3 liter jars, 3 raw eggs and of course salt. Learned? It seems that everyone in childhood made eggs float in water.
pouring plain water to banks. Add 2 tablespoons of salt to one of them, 5 tablespoons of salt to the other. Mix everything well and dip the eggs into the water.
- at the bank with fresh water the egg will sink.
- In a jar with a bit of salt, the egg will float in the middle of the jar.
- And in cool brine the egg will float to the surface.
Why is this happening?
Salt water is denser, heavier than regular, fresh water. So she keeps the egg on the surface. So in a salt lake you can lie on the waves, like on a sofa and read a book. It's all about the density of water.
Pour some water into a glass. Then they lowered the cork and a piece of paraffin candle. They floated like boats on the surface of the water. Pour oil into a glass. It turned out that the cork continued to float on the surface, but already oil, and the paraffin sank lower into the oil layer.
Why did it happen?
Oil is lighter than water, so it sits above water. Cork is lighter than oil, and paraffin is lighter than water, but heavier than oil. This is such an easy-to-heavy story :)
Knowing the density of some substances, come up with your own multilayer liquids. Density is specified in g / cm 3
- Honey 1.35
- Glycerin 1.30
- Whole milk 1.03
- Pure water 1.00
- Sunflower oil 0.93
- Ice 0.90
- Alcohol 0.80
- Gasoline 0.71
- Cork 0.24
See also our experience on the density of substances :)
Experiments are different and not only with liquids. And we have already carried out experiments with densities today. Therefore, I want to GIVE you a collection of experiments with sound. Add volume, ringing and some controlled noise to your life. Believe me, it's very interesting.
Successful experiments! Science is fun!
The grim allegation of a "white death" must be refuted. Of course, the abuse of salt can easily ruin the cardiovascular and urinary systems and bring oneself to the grave prematurely. But so the abuse of any product is fraught with serious consequences, all excesses are harmful, including salt.
Salt is life, not death. Without salt, the existence of the organism of mammals is impossible. All biological fluids - blood, sweat, urine, saliva, tears, sputum - contain sodium and chlorine ions. The main role of sodium chloride is to maintain osmotic constancy and constancy of the volume of the liquid. Sodium-potassium pump ensures cell integrity; in addition, sodium and potassium are involved in the conduction of nerve impulses. Sodium ions are also involved in the transport of amino acids and sugars into cells. The higher the concentration of sodium ions in the intercellular fluid, the higher the ability of cells to transport amino acids into the intracellular space. Sodium and chlorine are also involved in digestion (without hydrochloric acid, food cannot be digested in the stomach), in many metabolic processes, sodium and chlorine ions are necessary to create the desired acid-base balance in cells and tissues and for the action of individual enzymes.
The proclamation of salt as "white death" was based on historical fact: our primitive ancestors did not know salt and did very well without it. Is that how they got along? So you didn't know? Salt was part of the plant and animal food of the primitives, in which they did not limit themselves (due to the irregular availability of food, they ate for the future), and then people discovered that salt significantly improves the taste of food and makes it more satisfying. The healing properties of salt, its cleansing and disinfecting effect were also discovered. And then they revealed the remarkable property of salt to keep food (meat, fish, vegetables) unspoiled during long-term storage, salt turned out to be an excellent preservative. Then they mastered the technological use of salt for dressing skins and furs, later they began to use it in the household for washing glass and crystal and in cosmetic purposes, for skin care.
Salt firmly entered a person's life and immediately became a value, because it was not cheap. In ancient times, salt was mined as follows: they evaporated (in the south) or frozen out (in the north) sea water and water from salt lakes, used salted ash, and found natural rock salt. Salt was served on the table in expensive salt shakers, it was cherished, saved, boasted about it: the presence of salt on the table was a sign of prosperity and prosperity. Salt was stockpiled in case of disasters and paid with it instead of money. The Latin word "salarium" and the English word "salary", meaning "salary", "salary", are of "salt" origin. Because of salt, there were civil unrest and military clashes - remember the famous "salt riots" and wars over rock salt deposits and salt reservoirs. The value of salt gave rise to a number of proverbs, sayings, aphorisms, which emphasized the deep significance of salt in human life. One saying “you can live without gold, but you can’t live without salt” is worth something!
And in the progressive twentieth century in civilized countries, salt was undeservedly repressed, indiscriminately accusing it of the emergence and development of various ailments. And they began to urge everyone (all of them!) to avoid salt, to reduce its consumption to a minimum, and it is better not to salt food at all. Another excess in the preaching of proper nutrition!
Table salt has many faces and is both useful and harmful. If you control its content in the diet and observe the "golden mean", then salt will go exclusively for the benefit and fully justify the phrase "salt of life."
The daily requirement for salt in temperate climate zones is 10-15 g per day. In hot countries, there is more sweat, more fluid intake, so more salt is needed. In cold climates water-salt exchange not so intense, salt intake is less there. The need for salt increases with physical activity. And it is recommended to drink water to quench thirst not boiled, not distilled, but mineral, which includes sodium chloride. And after intense exercise (for example, after long walks), it is recommended to drink lightly salted water and not try to quench your thirst with clean water from mountain streams, where the salt content is very low. With significant losses of sodium chloride by the body (uncontrollable vomiting, prolonged diarrhea), the amount of salt consumed is greatly increased, and in some cases it is even necessary to inject a salt solution intravenously.
The addition of salt during cooking and in ready-made meals is necessary; it is not enough with natural products. Note that even animals like to lick salt licks, i.e. instinctively drawn to the salty. For a normal person in normal, non-extreme conditions, the consumption of salt is approximately the same: 10 g in the form natural products and 5 g for adding salt to food when cooking and salting during meals. Salt content in foods varies greatly: it is highest in bread and cheese; in plant and animal products, it depends on the type, growing conditions, the part of the body used for food, and sodium chloride is completely absent in granulated sugar.
In some diseases, it is recommended to severely limit salt - in cardiovascular, inflammatory, kidney failure. The restriction of salt in diet tables No. 7 and No. 10 is especially significant (according to the nomenclature diet tables developed at the Institute of Nutrition of the Russian Academy of Medical Sciences). In some cases, doctors prescribe salt-free diets - there in the food there is only the salt that is contained in the products, without additional salting, and products with high content sodium chloride (cheese, for example) is excluded. And in the most severe cases, special salt-free bread is prescribed. In such cases, the taste of food should be given with other spices, those allowed by the doctor: pepper, dried herbs, vinegar, lemon acid. With a skillful combination of permitted products and skillful cooking, everything will be in order with taste sensations and health.
TO SALT OR NOT TO SALT?
Restriction of salt in the diet: with renal failure, coronary heart disease, hypertension, inflammatory processes, as well as obesity. In some severe cases, salt-free diets are prescribed with the complete exclusion of salt from the salt shaker, only the salt that is contained in the products is present in the diet. But such salt-free diets are not prescribed for obesity, especially for alimentary, when a person “ate” his overweight because of his unbridled appetite. Desalted food is tasteless, poorly satiating and makes you want to eat something tasty. And hence the breakdown from the diet, and bouts of bulimia.
Unfortunately, salt-free diets for weight loss are often used on their own, bypassing medical recommendations. After all, the easiest way to lose weight is by reducing the amount of water in the body, and you can reduce the amount of water by reducing the amount of salt consumed, even without resorting to diuretics. With such an unreasonable method of losing weight, in addition to water, vital elements, including sodium, chlorine, potassium, and magnesium, also leave the body. On a salt-free diet, you can quickly lose weight, in just a few days, but not for long, this weight will soon return back (well, if without weight gain) - because the fluid in organs and tissues is quickly restored. Moreover, this imaginary weight loss - this is not a decrease in fat, but simply pumping out water - will take place with such side effects, as a deficiency of useful elements with all the ensuing consequences, various complications with the kidneys, tachycardia, deterioration of the skin and hair.
For cooking and salting, in addition to ordinary salt obtained from different sources and in different ways (rock salt, boiled water, garden salt), food salt is also used. maritime salt, in which, in addition to sodium chloride, potassium chloride, magnesium chloride, magnesium carbonate, calcium sulfate, and also iron, boron, iodine, phosphorus, silicon are presented. Due to these mineral additions, sea salt is considered more beneficial. They also use iodized salt, fluorinated, iodized-fluorinated and the so-called “reduced sodium salt” - where part of the sodium chloride is replaced by potassium chloride, and it is recommended for those who are forced to reduce their salt intake for health reasons. And the most “complete” salt is salt containing, in addition to sodium and chlorine, potassium, magnesium and iodine, and in the most “advanced” versions that go on sale, all these elements are quantitatively presented in the optimal ratio.
For the preparation of soups, potatoes, vegetable and cereal dishes, it is convenient to use salted blanks. seasonal vegetables: garden greens, sorrel, green tomatoes, red and green peppers, separately or in different combinations, finely chopped and thickly sprinkled with salt (it is better to use coarse rock salt for this); In this form, they are perfectly stored in the refrigerator for several months. Vegetable brines can also be used for soups and hodgepodges, brine from olives and olives is especially valuable. However, brine is most often used differently - as a universal remedy for relieving a hangover. Timely intake of brine also relieves the urge to vomit (relevant for pregnant women) and is good cosmetic- brine baths make hands soft and tender, and washing the face with brine visually rejuvenates it (due to the influx of water to upper layers skin and smoothing fine wrinkles) - these recipes in past centuries were widely used by both aristocrats and commoners.
For the taste of dishes, it is very important when, at what stage salt is added to them. It is known that salt prevents boiling, therefore salt is better to add not at the beginning of cooking, but shortly before its end. And if an inexperienced culinary specialist slightly oversalted the soup or stew, then you can correct the situation by adding a potato and a handful of rice - they will take over extra salt. But it is better not to salt everything - you can add salt to the finished dish. As the saying goes, “undersalted on the table, and oversalted on the back” is a saying for negligent housewives. Especially unfortunate cook will get from those households and guests who diligently avoid salt (for medical reasons or because of an ingrained habit); so in order to avoid their anger, deliberately undersalt, and salads from fresh vegetables do not add salt at all, giving eaters the right to bring food to the desired salt condition on their own. Salt shaker on the big dining table it is better to put a few, so that the diners do not look for salt and do not ask to pass it from the other side. And the salt should not be damp and crumbly. To do this, store it in a dry place and add a little starch and / or a few grains of rice to it - this will save it from moisture and lumps.
Excessive passion for salt is harmful, especially regular abundant salting, for which salt lovers are popularly called "salty souls". Such salt-loving "salty souls" are drawn to the salt shaker without even tasting the food, and normal salting seems insipid to them. Meanwhile salted food is the occurrence of edema, an increase in the load on the kidneys, an increase in blood pressure and the early development of atherosclerosis. And one more insidiousness: overly salty snacks stimulate the appetite, and hence overeating, leading to overweight- an unpleasant burden on the whole body: primarily on cardiovascular system and on musculoskeletal system. And it has been noticed that after salty dishes, he is drawn to fatty and sweet. That is why in some restaurants salty snacks are cunningly served, so that after them the visitor will certainly order something “dense”, and then also confectionery.
Pickles, marinades, corned beef and smoked meats should take the last place in your diet. And when using ready-made seasonings and sauces, you need to pay attention to the label, which indicates the salt content. Sometimes sauces are naively considered salt substitutes and boast: “I excluded salt altogether, I completely replaced it with soy sauce!”. So soy sauce mixed with table salt, it is she who gives it a salty taste.
In general, with salt, once declared "white death", follow the principle of reasonableness - and you will have a long life.
RECIPES
For those who are forced to limit salt
Salad "Saltless" - a classic dish of dietary cuisine
Finely chop fresh cabbage, rub, add cranberry juice, raw grated beets, sugar, sour cream and mix well. Calculation: for 200 g of cabbage 20 g of beets, juice from 10 g of cranberries, 30 g of sour cream, 10 g of sugar.
Solyanka-blende
Mix chopped fresh and sauerkraut in a 3:1 ratio, finely chop one large onion for 500 g of the cabbage mixture and load the vegetables in a Teflon pan or Pyrex microwave container, previously greased with deodorized vegetable oil, and at the bottom of the dish there should be a layer of oil a centimeter thick. Stew over low heat on a divider or in the microwave in the “vegetables” mode. When the vegetables have a uniform color, add a 100-gram piece of raw smoked meat (brisket, neck or tenderloin) or sausage (raw smoked or salami) and simmer with it until tender, i.e. until the vegetables are firm. Then put in salt Bay leaf and simmer for 1 more minute. Then take out the meat (sausage) and give it to someone for whom it is nutritionally suitable (teenager, youth, athletic man). And leave yourself a hodgepodge that absorbed the taste and smell of smoked meat, absorbed a small amount of salt and fat from there, and at the same time retained its dietary value.
For lovers of salty snacks
Homemade red fish
For the manufacture of this delicacy, fish from the salmon family is used: chinook salmon, salmon, trout, chum salmon, pink salmon - choose based on availability and your financial means. You can pickle a whole fish, or you can even a piece. It is better to take a piece from the middle. Gut the fish and remove the scales, but do not peel off the skin. Rub the fish thoroughly on both sides with a mixture of salt and granulated sugar, place in a porcelain bowl, put oppression and leave to stand at room temperature for two days. Then drain the leaked liquid, remove the skin and pull out the backbone (everything easily leaves in salted fish) and place cooked fish into the refrigerator. And put the fish pickle, skin and backbone into fish soup(fish head and tail will also go there) or add to rice when cooking, it will be delicious rice with a fishy touch. Such red fish is stored in the refrigerator for 2-3 weeks, cut into pieces and enjoy. Calculation: for 1 kg of fish, two tablespoons of salt and one tablespoon of granulated sugar.
Pickled cucumbers of simplified preparation
Wash the cucumbers well, cut the long specimens into two or three pieces, put them tightly in a glass jar, pour the prepared brine and leave for 2-3 days at room temperature, then place in the refrigerator. Salted cucumbers will be ready in 3 days. Preparation of brine: per 1 liter boiled water 30 g common salt, 1 teaspoon store-bought grated horseradish, 4-5 medium cloves of garlic, a few stalks of green dill and / or half a teaspoon of dried dill seeds, 5-7 black peppercorns or a small piece (about the size of a fingernail) dried red pepper. You can add 1-3 more clove buds and a couple of bay leaves. All this stir and let stand until the salt is completely dissolved. Shake the brine before pouring the cucumbers.
Olga Zaikina, candidate of biological sciences
Natalya Belyaeva
Cognitive-experimental lesson in the preparatory group "Secrets salt water»
Integrated
Target: To consolidate children's ideas about three states of aggregation water (liquid, solid, gaseous). Create problem situation to study the properties of table salt and its aqueous solution. Develop the ability to reason and draw conclusions. Expand view statements about the interaction between man and nature.
Materials and equipment: Containers 1 liter, water, a pack of table salt, raw peeled potatoes, a raw egg, a tablespoon, a candle, scales, material for the experiment (for each child, A3 sheets for sketching, markers, information search cards.
Preliminary work: A series of experiments on the study of the properties of fresh water, on the dissolution of various substances in water.
Lesson progress:
Hello whys! I am glad to welcome you to our club.
Let's talk today about the properties of water. What properties of water do you know? What else can be called water?
Today we will interesting experiences and learn something new again. Remember how you can learn new things. (Schemes of information search are exposed).
I put a jar of salt water on the table, put an egg in it - it floats. Then I add fresh water to the container - the egg sinks to d But.
Would you like to know the secret of this experience? See what else I have. (I put on the table a container of fresh water, a pack of table salt, a peeled potato .) I will put a raw potato in a jar of water. What happened to her? (The potato sank to the bottom.) Children at their tables do the same.
In this jar there is water, and in the pack there is some unknown substance. I wonder what it is? How to test your assumptions? Remember how you can test an unknown substance? Can you taste it? Why not? That's right, trying an unfamiliar substance is dangerous. But I know what it is, and I give you permission to try it. (Children try a few grains of salt, determining it to taste.) Yes, it's regular salt. You reasoned correctly and drew the right conclusion.
Let's get back to our research. What happens to a potato when we put it in a jar of water? (She is sinking) Add a few tablespoons of salt to another jar of water and stir so that the salt dissolves faster. (Child performs the task.) What happened? (Salt solution.)
(I dip the potato in the salt solution). What happened to the potato? (She surfaced). Some strange potato: sometimes it wants to swim, sometimes it wants to lie at the bottom. But maybe it's not the potato? What then? (Assumptions of children.) In this bank - salty water, and in this one - fresh, unsalted. Now can you tell why in the previous experiment the egg either floated on the surface of the water or sank? We know that salt is in sea water. Salt water is heavier and denser than fresh water. Swimming in sea water is much easier, as it pushes the body. How can you be sure. That salt water is heavier than fresh water? (You can weigh jars of salt and fresh water.)
I invite one of the children, and together we weigh containers with salt and fresh water.
Let's return to our experience and try to add salt to the solution. What's going on with potatoes? Can you tell how much salt is in water? How to do it? Can you taste it?
We know that water freezes at low temperatures, and boils and turns into steam at high temperatures. Do you think salt water can be in a gaseous state?
It's not hard to find out. We collect salt water in a spoon and heat it over a candle flame. What happened? What's left at the bottom of the spoon? Why didn't the salt evaporate with the water? It turns out that not all substances can, like water, be in three different states. Salt is a solid and cannot become gaseous. Remember what happened to ice when heated, maybe salt will become liquid when heated? What happened? What conclusion can we draw?
We have found answers to difficult questions thanks to the fact that we worked together, tested our assumptions with the help of experiments.
Homework- Try to answer the question. Can salt water be solid.
Article from the "Big Encyclopedia" ed. S.N. Yuzhakova, 1904
Salt (common salt, sodium chloride), NaCl, a chemical compound consisting of 39.32 parts of sodium and 60.68 parts of chlorine, is formed by burning sodium in chlorine, or by decomposing sodium carbonate (soda) with hydrochloric acid (hydrochloric acid). Table salt crystallizes in anhydrous cubes containing a little mother liquor, as a result of which they crack when heated. At a temperature of 10 °, table salt crystallizes in large six-sided tablets, decomposing when heated into water and cubes. Pure salt does not become wet in air, melts at 772° and evaporates at highest temperature, especially with air current; when solidified, it crystallizes in cubes. Specific whole her 2.15. At the boiling point, the salt is slightly more soluble than at ordinary; 100 parts of water dissolve at:
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Weight amounts of salt |
wt% salt in solution |
Specific gravity of the solution |
Grams of salt in 1 liter |
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1 part salt dissolves:
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Parts of water |
A solution with 26% salt freezes only at -18.43 °. A saturated solution boils at ordinary pressure at 109.7° and contains 28.75% salt. Saturated solutions salts can be concentrated by freezing, and water at low temperatures is released in the form of ice. The formation of ice occurs at a lower temperature than the freezing of water and the lower, the stronger the solution, and ice always contains a little salt. When salt is dissolved in water, the volume of the solution becomes less (by 24.5% of the volume of solid S.) than the volume of both bodies before they are combined.
Specific gravity of salt solutions at 15°
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Specific gravity |
Specific gravity |
Specific gravity |
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At 15 ° alcohol of various strengths dissolves:
Salt mining.
Salt is found in nature dissolved in the water of the oceans, seas and salt lakes (Caspian, Aral Sea, Dead Sea, Utah), in salt springs and rivers (Karizaha, which flows into Lake Eltonskoe, Rio ensalado in Chile, whose water contains up to 32% chloride compounds). In the solid state, it is found in the form of rock salt, wall salt and in deserts. Rock salt plays a significant role in the formation of the earth's crust. In many countries there are huge deposits and stocks of pure rock salt, anhydrite, dolomite, marl, gypsum containing salt. Pure layers of salt are often covered with a layer of saline clay and in many places there are layers of pure rock salt one above the other, alternating with layers of clay. Oxenius explains the formation of rock salt deposits by the existence of deep sea bays with an approximately horizontal strait, which admits the water of the seas only insofar as water can evaporate from the surface of the bay for a certain time.
With a dry and warm climate and strong evaporation, a concentrated and therefore heavier salt solution is formed in the strait, which constantly flows into the depths of the bay. From the concentrated solution obtained here, the salt separates in crystals. After a salt deposit has been formed in this way and covered from above with more soluble salts of the mother liquor, a circular process should form, when sea water flows into the bay from above in the strait, and the mother liquor flows from below. The first, when mixed with a concentrated solution, precipitates gypsum and polyhalite, and the longer this period lasts, the greater will be the covering layers of gypsum or anhydrite. If during this period the bay separates from the sea, then the mother liquor crystallizes over the layers of gypsum and anhydrite. Some salt deposits (Stasfurt, Kaluets) are covered with a thick layer of crystallized mother liquor salts (Abraumsalze), although very often they are washed away again and only traces of them remain.
On fig. 1 shows the development profile of two very different rock salt deposits; the lower old layer of still unknown thickness, with an admixture of other minerals of anhydrite, polyhalite and kieserite, is separated from the upper one by valuable layers of potassium salts, salt clay, anhydrite and gypsum from a newer deposit. The latter in mine I reaches a thickness of 60 meters, is covered with gypsum and a layer of variegated sandstone formation gradually wedges out upwards, and is the purest salt, which is mined.
In Germany there are large deposits of salt, reaching 1500 meters in thickness, stretching from Heligoland to Inowratslav and forming deposits of Stasfurt, Erfurt, etc. In addition, there are deposits in Württemberg, Alsace, Lorraine, Salzburg, etc. In Austria-Hungary, there are deposits in Tyrol , Salzkamergut, large deposits of Wieliczka, Bosnia, Stebnik and Zlanina, Sugatag and Siebenbürgen. Romania has deposits in the Transylvanian Alps. In addition, in Spain there are deposits in Catalonia and Cordoba, in Italy (Sicily), in Switzerland (Bex), France (Meurthe et-Moselle, Jura, Ariense, Bas-Pyrenees), in England (Bleshiere, Middler borough on Tees). Russia is very rich in rock salt deposits, the most important are deposits of the Bryansk deposits, Ekaterinoslav province, Iletsk protection of the Orenburg province, Kulpinsky, Nakhichevan, deposits of the Kars region, Perm province, Astrakhan province. and various areas of Siberia.
Rock salt is found in almost all formations (from mica schist to Tertiary sediments) usually accompanied by anhydrite and gypsum. Many deposits directly come to the surface of the earth, others are discovered thanks to drilling operations. Mining of deposits of pure rock salt is usually carried out by drifts, as indicated in Fig. 2 and 4, Table I. There are also bottle-shaped workings used in Romania and Hungary, and post-workings used in Stassfurt and the Bryansk mines. The development is facilitated by the fact that rock salt is a very durable material and allows you to work without fasteners. Rock salt is often completely colorless and easily breaks up into shiny cubes or forms yellowish, reddish and greenish-brown crystalline masses containing iron oxide, clay, ciliates, etc. The table shows some analyzes of rock salt from the most important deposits:
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Sodium chloride |
Potassium chloride |
Calcium chloride |
magnesium chloride |
Sodium sulfate |
Potassium sulphate |
Sulfuric acid calcium |
Magnesium sulphate |
Insoluble substances |
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Stassfurt |
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Stassfurt |
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Inowratslav |
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Sumbakovaya |
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Bakhmutskaya |
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Perm |
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Perm |
In addition to these constituent parts in rock salt, ferrous chloride, compounds of bromine, iodine and fluorine, ammonia, phosphates, borates, etc. are found. Some salt samples contain highly compressed gases (methane, carbon dioxide, air), which destroy crystals when heated. Rock salt goes on sale in the form of lumps, pieces or in powder and directly goes into use. In places of salt deposits and in general in nature, in addition to rock salt, there are numerous salt brines and springs that come to the surface of the earth or fill specially arranged mines for this purpose, from where brines are pumped out. Such springs are very rarely saturated and contain from 2% to 24% common salt with an admixture of sulfate and chloride salts of other metals, iron, silica, etc. In addition, the waters of the springs contain: iodides, bromides, compounds of rubidium, cesium, waist, organic matter, carbonic acid, etc. Strong brines evaporate, weak ones are concentrated by freezing (Okhotsk, Irkutsk) or by evaporating them at ordinary temperature). Weak brines are first processed in cooling towers (see table), cleaned, brought to a concentration of 15-20% and then evaporated. To work with cooling towers, it is better to use the warmest time of the year, in Germany 200-260 days a year.
Sufficiently concentrated and purified brine, when boiled, thickens by heating or evaporation in salt works (see table), where finely or coarsely crystalline salt is obtained. The first usually consists of an empty deep pyramid with stepped sides, consisting of individual cubes. Evaporation vats or reservoirs are usually flat, made of iron, and heated either simply with coal or steam, or by blowing hot gases onto the surface of the solution. The size of the boilers is from 45 to 335 square meters. m. At the beginning of the operation, the brine is boiled strongly, while the resulting foam and sludge are removed and a new brine is added until the solution is saturated during boiling, it is allowed to lighten and transferred to other vats in which salt begins to form. The resulting salt is usually white color, but with constant work it becomes contaminated, to avoid which it is necessary to release the mother liquor, then the salt is dried in special rooms or in iron boilers heated from below (see table). The best table salt is centrifuged and dried in tin-plated copper vessels with blown hot air.
In England, hot concentrated brine is poured into wooden molds, in which it solidifies into blocks, which are gradually dried in dryers.
Sea waters in 1 cu. meter contain an average of 26-31 kg. sodium chloride, 3-7 kg. magnesium chloride, 0.5-6 kg. magnesium sulfate, 0.14-6 kg. sulfate lime, 0.0111 kg. potassium chloride. Many salt lakes in the hot season precipitate large amounts of salt in the form of accumulations that are easily mined (Lake Elton, Utakh, Kara-Bugaz). In the south of Russia, natural bays and estuaries are used to evaporate sea water until a layer of salt from 2 to 30 cm thick is formed. In places with a hot climate on the shores of the seas, a large amount of salt is extracted from sea water, as, for example, in Portugal, Spain, France on the Mediterranean Sea (Languedoc) and the Atlantic Ocean, in Italy, Dalmatia, Istria and in the United States. To do this, they arrange fences lined with clay with a large evaporation area, forming a system of flat pools filled with sea water pumps, or fencing off bays. Iron oxide precipitates in them first, then gypsum, followed by the crystallization of table salt. The salt that precipitates first is the purest and goes to the table. At the end of summer, the crystallization pools are dried, the salt is piled up and exposed to the action of atmospheric humidity, which cleans it from the mother liquor and, if they want to get it in a completely pure form, it is recrystallized. Usually 80-85% of the salt contained in sea water is obtained. With greater evaporation, a mixture of sodium chloride and magnesia sulfate is obtained, bringing it to the composition 2NaCl + MgS0 4, dissolving in water and cooling with ice machines to -6 °, Glauber's salt Na2SO 4 is forced to crystallize. The last mother liquor gives bitter salt MgSO 4 in winter. With further evaporation in the summer, table salt, magnesium sulfate, kainite are obtained, and the remaining solution is processed into bromine.
Table salt almost always contains small amounts of sulfate and chloride compounds of sodium, calcium, magnesium and potassium, less often and only traces of iron oxide and bromide compounds of potassium and sodium. Due to the content of calcium chloride and magnesium, it becomes moist in the air. The water content must not exceed 6%.
Table salt is very common in animal organisms and in the liquids of the latter in a predominant amount compared to others. minerals. Its content in the blood is usually constant and does not depend on nutrition. Saliva, gastric juice, mucus, pus and inflammatory exudates are especially rich in it. All common salt comes from food and leaves the body in urine, feces, mouth, nose and sweat. A normal person weighing 64 kg. excretes 11.9 grams of salt per day in the urine, converting some of it into other compounds in the body. Salt acts in the body, firstly, by its influence on diffusion processes, it is the main factor in the movement of fluids and serves as a source for the formation of hydrochloric acid in gastric juice. Adding it to food causes an increase in digestion, and human instinct recognizes the addition of it as something necessary, which is developed in all peoples at all times.
Noteworthy is the fact that table salt is necessary for animals that eat plant foods and do not eat meat. On the chemical side, table salt in the body gives hydrochloric acid to the gastric juice; it is possible that it is closely related to the formation of cells. The amount of table salt needed per year for a person is considered to be 7.5 kg. Little is known about the action of table salt in the vegetable kingdom, but its excess harms the seeds and forms infertile soil. In some cases, it is useful in that it converts calcium salts, phosphates, etc., necessary for plants, which are used for fertilizer, into soluble compounds.
In technology, table salt is used to prepare soda, chlorine, ammonia, in metallurgy for chlorinating roasting of silver ores and poor copper, in the preparation of aluminum, to obtain sodium, for soap, in the preparation of tobacco, mineral waters, baths, for glazing clay products, for preserving the wood of ships and sleepers, for salting fish, meat, oil. In agriculture, table salt is used for fertilizer and livestock feed.
Salt production in recent years in various states is shown in the table in millions of pounds:
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1891 |
1894 |
1898 |
1899 |
1900 |
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Great Britain |
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Germany |
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United States |
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For 10 years, salt production in Russia is presented in the following table in pounds:
|
Of the year |
Stone |
self-sedimentary |
Boiler |
Total |
See Karsten, Salinonkunde (Berl., 1846-47, 2 vol.); Kerl, "Salinenkunde"; Hehn, "Das Salz" (1873); Moeller, "Das Salinen in seiner kulturgeschichtlichen und naturwissenschaftlichen Bedeutung" (1874); Schwarz, "Vorkommen und Bildung des Steinsalzes" (Halle, 1885); Wagner, "Chemical Engineering"; Dammer, Chemische Technologie.
Article "Salt" from the "Great Encyclopedia", ed. S.N. Yuzhakova, St. Petersburg, "Enlightenment", 1904, volume 17, pp. 654-657
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