Chemical reactions with mg. Characteristic chemical properties of Be, Mg and alkaline earth metals
The science that studies these elements is chemistry. The periodic table, based on which this science can be studied, shows us that there are twelve protons and neutrons contained in a magnesium atom. This can be determined by the serial number (it is equal to the number of protons, and there will be the same number of electrons if it is a neutral atom, not an ion).
The chemical features of magnesium are also studied by chemistry. The periodic table is also necessary for their consideration, since it shows us the valency of the element (in this case, it equals two). It depends on the group to which the atom belongs. In addition, with its help you can find out that the molar mass of magnesium is twenty-four. That is, one mole of this metal weighs twenty-four grams. The formula of magnesium is very simple - it does not consist of molecules, but of atoms united by a crystal lattice.
Characteristics of magnesium in terms of physics
Like all metals except mercury, this compound has a solid state of aggregation under normal conditions. It has a light gray color with a peculiar sheen. This metal has a fairly high strength. On this physical characteristic magnesium does not run out.
Consider the melting and boiling points. The first is equal to six hundred and fifty degrees Celsius, the second is one thousand ninety degrees Celsius. It can be concluded that this is a fairly low-melting metal. In addition, it is very light: its density is 1.7 g/cm3.
Magnesium. Chemistry
Knowing the physical features of this substance, we can proceed to the second part of its characteristics. This metal has an average level of activity. This can be seen from the electrochemical series of metals - the more passive it is, the more to the right it is. Magnesium is one of the first on the left. Consider, in order, with which substances it reacts and how this happens.
With simple
These include those whose molecules consist of only one chemical element. This is oxygen, and fisphorus, and sulfur, and many others. Let us first consider the interaction with oxygen. It's called combustion. In this case, an oxide of this metal is formed. If you burn two moles of magnesium, while spending one mole of oxygen, we get two moles of oxide. The equation for this reaction is written as follows: 2Mg + O 2 = 2MgO. In addition, when magnesium is burned in the open air, its nitride is also formed, since this metal reacts in parallel with nitrogen contained in the atmosphere.
When burning three moles of magnesium, one mole of nitrogen is spent, and as a result we get one mole of the nitride of the metal in question. The equation of this kind of chemical interaction can be written as follows: 3Mg + N 2 = Mg 3 N 2.
In addition, magnesium is able to react with other simple substances such as halogens. Interaction with them occurs only when the components are heated to very high temperatures. In this case, an addition reaction occurs. Halogens include such simple substances: chlorine, iodine, bromine, fluorine. And the reactions are named accordingly: chlorination, iodination, bromination, fluorination. As you might have guessed, as a result of such interactions, you can get chloride, iodide, bromide, magnesium fluoride. For example, if we take one mole of magnesium and the same amount of iodine, we get one mole of iodide of this metal. This chemical reaction can be expressed using the following equation: Mg + I 2 = MgI 2. The same principle applies to chlorination. Here is the reaction equation: Mg + Cl 2 = MgCl 2.
In addition, metals, including magnesium, react with phosphorus and sulfur. In the first case, you can get phosphide, in the second - sulfide (not to be confused with phosphates and sulfates!). If you take three moles of magnesium, add two moles of phosphorus to it and heat it to the desired temperature, one mole of the phosphide of the metal in question is formed. Equation of this chemical reaction looks like this: 3Mg + 2P \u003d Mg 3 P 2. In the same way, if you mix magnesium and sulfur in the same molar proportions and create the necessary conditions in the form of high temperature, we get the sulfide of this metal. The equation for such a chemical interaction can be written as follows: Mg + S = MgS. So we examined the reactions of this metal with other simple substances. But chemical characterization magnesium does not end there.
Reactions with complex compounds
These substances include water, salts, acids. Metals react differently with different groups. Let's consider everything in order.
Magnesium and water
When this metal interacts with the most common chemical compound on Earth, oxide and hydrogen are formed in the form of a gas with a sharp unpleasant odor. To carry out this kind of reaction, the components also need to be heated. If you mix one mole of magnesium and water, you get the same amount of oxide and hydrogen. The reaction equation is written as follows: Mg + H 2 O \u003d MgO + H 2.
Interaction with acids
Like other reactive metals, magnesium is able to displace hydrogen atoms from their compounds. Such processes are called In such cases, metal atoms replace hydrogen atoms and form a salt consisting of magnesium (or another element) and an acid precipitate. For example, if you take one mole of magnesium and add it to in an amount of two moles, one mole of the chloride of the metal in question and the same amount of hydrogen are formed. The reaction equation will look like this: Mg + 2HCl = MgCl 2 + H 2.
Salt interaction
We have already described how salts are formed from acids, but the characterization of magnesium from the point of view of chemistry also implies consideration of its reactions with salts. In this case, the interaction can occur only if the metal that is part of the salt is less active than magnesium. For example, if we take one mole of magnesium and copper sulfate each, we get the sulfate of the metal in question and pure copper in an equal molar ratio. The equation for this kind of reaction can be written as follows: Mg + CuSO 4 = MgSO 4 + Cu. Here manifest restorative properties magnesium.
Application of this metal
Due to the fact that it is superior to aluminum in many respects - it is approximately three times lighter, but at the same time twice as strong, it has become widespread in various industries. First of all, this is the aircraft industry. Here, magnesium-based alloys occupy the first place in popularity among all materials used. In addition, it is used in the chemical industry as a reducing agent for the extraction of certain metals from their compounds. Due to the fact that when burning, magnesium forms a very powerful flash, it is used in the military industry for the manufacture of signal rockets, flash-noise ammunition, etc.
Getting magnesium
The main raw material for this is the chloride of the metal in question. This is done by electrolysis.
Qualitative reaction to cations of a given metal
This is a special procedure designed to determine the presence of ions of a substance. To test the solution for the presence of magnesium compounds, potassium or sodium carbonate can be added to it. As a result, a white precipitate is formed, which is easily soluble in acids.
Where can this metal be found in nature?
This chemical element is quite common in nature. The earth's crust is almost two percent composed of this metal. It is found in the composition of many minerals, such as carnallite, magnesite, dolomite, talc, asbestos. The formula of the first mineral looks like this: KCl.MgCl 2 .6H 2 O. It looks like crystals of bluish, pale pink, faded red, light yellow or transparent.
Magnesite is its chemical formula - MgCO 3 . It has a white color, but depending on the impurities, it may have a gray, brown or yellow tint. Dolomite has the following chemical formula: MgCO 3 .CaCO 3 . It is a yellowish-gray or glassy mineral.
Talc and asbestos have more complex formulas: 3MgO.4SiO 2 .H 2 O and 3MgO.2SiO 2 .2H 2 O, respectively. Due to their high heat resistance, they are widely used in industry. In addition, magnesium is included in chemical composition cells and structure of many organic matter. We will consider this in more detail.
The role of magnesium in the body
This chemical element is important for both plant and animal creatures. Magnesium is vital for the plant organism. Just as iron is the basis of hemoglobin, necessary for the life of animals, so magnesium is the main component of chlorophyll, without which a plant cannot exist. This pigment is involved in the process of photosynthesis, in which nutrients are synthesized from inorganic compounds in the leaves.
Magnesium is also very necessary for the body of animals. The mass fraction of this trace element in the cell is 0.02-0.03%. Despite the fact that it is so small, it performs very important functions. Thanks to it, the structure of such organelles as mitochondria, which are responsible for cellular respiration and energy synthesis, as well as ribosomes, in which the proteins necessary for life are formed, is maintained. In addition, it is included in the chemical composition of many enzymes that are needed for intracellular metabolism and DNA synthesis.
For the body as a whole, magnesium is necessary to take part in the metabolism of glucose, fats and some amino acids. Also, with the help of this microelement, a nerve signal can be transmitted. In addition to all of the above, sufficient magnesium in the body reduces the risk of heart attacks, heart attacks and strokes.
Symptoms of high and low levels in the human body
The lack of magnesium in the body is manifested by such main symptoms as high blood pressure, fatigue and poor performance, irritability and poor sleep, memory impairment, and frequent dizziness. Nausea, convulsions, trembling in the fingers, confusion of consciousness can also be observed - these are signs of a very low level of intake of this microelement with food.
The lack of magnesium in the body leads to frequent respiratory diseases, disturbances in work of cardio-vascular system and type 2 diabetes. Next, consider the magnesium content in foods. To avoid its deficiency, you need to know which food is rich in this chemical element. It should also be taken into account that many of these symptoms can also manifest themselves in the opposite case - an excess of magnesium in the body, as well as a lack of trace elements such as potassium and sodium. Therefore, it is important to carefully review your diet and understand the essence of the problem, it is best to do this with the help of a nutritionist.
As mentioned above, this element is the main component of chlorophyll. Therefore, you can guess that a large amount of it is found in greens: these are celery, dill, parsley, cauliflower and white cabbage, lettuce, etc. Also, these are many cereals, especially buckwheat and millet, and also oatmeal and barley. In addition, nuts are rich in this trace element: these are cashews, walnuts, peanuts, hazelnuts, and almonds. Also, a large amount of the metal in question is found in legumes such as beans and peas.
A lot of it is also contained in the composition of algae, for example, in seaweed. If the use of these products occurs in normal quantities, then your body will not lack the metal discussed in this article. If you do not have the opportunity to regularly eat the food listed above, then it is best to purchase nutritional supplements that include this trace element. However, before doing this, you should always consult with your doctor.
Conclusion
Magnesium is one of the most important metals in the world. It has found wide application in numerous industries - from chemical to aviation and military. Moreover, it is very important from a biological point of view. Without it, the existence of neither plant nor animal organisms is possible. Thanks to this chemical element, the process that gives life to the entire planet, photosynthesis, is carried out.
From this article, you will learn what magnesium is and see a real chemical miracle - the burning of magnesium in water!
In the 17th century, in the English town of Epsom, a bitter substance was isolated from a mineral spring, which had a laxative effect. This substance turned out to be magnesium sulfate hydrate or MgSO₄∙7H₂O. Because of the specific taste, pharmacists dubbed this compound "bitter salt." In 1808, the English chemist Humphrey Davy obtained an amalgam of the twelfth element using magnesia and mercury. Eleven years later, the French chemist Antoine Bussy obtained the substance in question with the help of magnesium chloride and potassium, reducing magnesium.
Magnesium is one of the most abundant elements in earth's crust. Most magnesium compounds are found in sea water. This element plays an important role in the life of man, animals and.
As a metal, magnesium is not used in its pure form - only in alloys (for example, with titanium). Magnesium allows you to create ultra-light alloys.
Physical properties of magnesium
It is a light and ductile metal of a silvery-light color with a characteristic metallic sheen.
Magnesium is oxidized by air, a sufficiently strong MgO film is formed on its surface, which protects the metal from corrosion.
The melting point of the silvery metal is 650°C and the boiling point is 1091°C.
Chemical properties of magnesium
This metal is covered with a protective oxide film. If it is destroyed, magnesium will quickly oxidize in air. Under the influence of temperature, the metal actively interacts with halogens and many non-metals. Magnesium reacts with hot water to form magnesium hydroxide as a precipitate:
Mg + 2H₂O = Mg(OH)₂ + H₂
If magnesium powder is ignited on a gas burner in a special chemical spoon and then lowered into water, the powder will begin to burn more intensively.
Here's how it goes:
Due to the intensely released hydrogen, it will be accompanied by . In this case, magnesium oxide is formed, and then its hydroxide.
Magnesium belongs to active metals, and therefore violently interacts with acids. However, this does not occur as violently as in the case of the alkali metal potassium, that is, the reaction proceeds without ignition. But with a characteristic hiss, hydrogen bubbles are actively released. And although the hydrogen bubbles lift the metal, it is not light enough to stay afloat.
The equation for the reaction of magnesium and hydrochloric acid:
Mg + 2HCl = MgCl₂ + H₂
At temperatures above 600 °C, magnesium ignites in air, emitting extremely bright light in almost the entire spectrum, similar to the Sun.
Attention! Do not try to repeat these experiments yourself!
Such a blinding flash can injure the eyes: you can get a retinal burn, and in the worst case, you can lose your eyesight. Therefore, such an experience is not only among the most beautiful, but also among the most dangerous. It is not recommended to carry out this experiment without special protective dark glasses. you will find a magnesium burning experiment that can be done safely at home.
During the reaction, a white powder of magnesium oxide (also called magnesia) is formed, as well as magnesium nitride. Combustion equations:
2Mg + O₂ = 2MgO;
3Mg + N₂ = Mg₃N₂.
Magnesium continues to burn both in water and in the atmosphere carbon dioxide, so putting out such a fire is quite difficult. Extinguishing with water only exacerbates the situation, as hydrogen begins to be released, which also ignites.
An Unusual Use of Magnesium as a Light Source (1931)
The 12th element is very similar to the alkali metal. For example, it also reacts with nitrogen to form nitride:
3Mg + N₂ = Mg₃N₂.
Also, like lithium, magnesium nitride can be easily decomposed with water:
Mg₃N₂ + 6Н₂О = 3Mg(OH)₂ + 2NH₃.
The 4th analytical group includes cations Mg 2+ , Mn 2+ , Fe 2+ , Fe 3+ .
Hydroxides of group IV cations are insoluble in excess alkali and ammonia solution. They are quantitatively precipitated with an excess of NaOH solution, in the presence of hydrogen peroxide, which is a group reagent for ions of this group. All cations form sparingly soluble phosphates, oxalates, sulfides (except Mg 2+). Mn 2+ , Fe 2+ , Fe 3+ exhibit redox properties.
Reactions of magnesium ions
Reaction with alkalis.
Caustic alkalis form a white gelatinous precipitate of magnesium hydroxide:
MgCl 2 + 2NaOH \u003d Mg (OH) 2 + 2NaCl
Magnesium hydroxide is soluble in acids and ammonium salts, but insoluble in excess alkali.
Reaction with an aqueous solutionNH 3 .
Ammonia with magnesium ions forms a precipitate of magnesium hydroxide:
Mg 2+ + 2NH 3 ˙ H 2 O \u003d Mg (OH) 2 + 2NH 4 +,
which does not settle completely. In the presence of ammonium salts, the dissociation of NH 3 ˙ H 2 O decreases so much that the concentration of OH ions becomes less than necessary in order for the solubility product of Mg (OH) 2 to be exceeded. In other words, NH 4 Cl and NH 3 form a buffer solution with pH = 8.3, at which magnesium hydroxide does not precipitate.
3. Reaction with sodium hydrogen phosphate.
MgCl 2 + Na 2 HPO 4 \u003d MgHPO 4 + 2NaCl
Magnesium hydrogen phosphate is a white amorphous precipitate, soluble in mineral acids, and when heated, in acetic acid.
Executing a reaction: when carrying out the reaction in the presence of NH 3 ˙ H 2 O and NH 4 Cl precipitate a white crystalline precipitate of magnesium and ammonium phosphate. 3–4 drops of magnesium salt (tasks) are placed in a test tube, an ammonia solution is added to a weak turbidity, an NH 4 Cl solution until it dissolves, and 2–3 drops of a Na 2 HPO 4 solution. The test tube is cooled under cold water, rubbing a glass rod against the inner walls of the test tube . In the presence of magnesium ions, a white crystalline precipitate forms over time:
MgCl 2 + Na 2 HPO 4 + NH 3 ˙ H 2 O \u003d MgNH 4 PO 4 + 2NaCl + H 2 O
The reaction can also be carried out as microcrystalloscopic. A drop of magnesium salt (tasks), a drop of NH 4 Cl is applied to a glass slide, kept over a bottle with a concentrated solution of NH 3 (drop down), a crystal of dry Na 2 HPO 4 12H 2 O is added and after a minute crystals of MgNH 4 PO 4 are observed in the form of dendrites (leaves) under a microscope.
Reaction with ammonium carbonate.
2MgCl 2 + 2(NH 4) 2 CO 3 + H 2 O \u003d Mg 2 (OH) 2 CO 3 + 4NH 4 Cl + CO 2
The precipitate is slightly soluble in water and precipitates only at pH> 9. It is soluble in ammonium salts, which can be explained based on the following equilibrium: Mg 2 (OH) 2 CO 3 Mg 2 (OH) 2 CO 3 2Mg 2+ + 2OH – + CO 3 2–
With the introduction of NH 4 Cl, it dissociates NH 4 Cl NH 4 + + Cl - . Ions NH 4 + bind with hydroxide ions into a low-dissociating compound NH 3 ˙ H 2 O, as a result of which the concentration of OH ions decreases and is not reached and the precipitate dissolves.
5. Reaction with 8-hydroxyquinoline.
8-hydroxyquinoline in an ammonia medium at pH 9.5–12.7 forms a greenish-yellow crystalline precipitate of the intra-complex salt of magnesium oxyquinolate Mg (C 9 H 6 NO) 2 2H 2 O with magnesium ions:
Mg 2+ + 2C 9 H 6 NOH + 2NH 4 OH \u003d Mg (C 9 H 6 NO) 2 + 2NH 4 +
The precipitate is soluble in acetic and mineral acids. Alkali and alkaline earth metal cations do not interfere with the reaction.
Executing a reaction: 2 drops of phenolphthalein solution and 2 M ammonia solution are added dropwise to 3–4 drops of the test solution until a pink color appears. The contents of the tube are heated to a boil and 4-5 drops of a 5% alcohol solution of 8-hydroxyquinoline are added. In the presence of magnesium, a greenish-yellow precipitate forms. The reactions are not interfered with by alkali and alkaline earth metal ions.
To the family alkaline earth elements include calcium, strontium, barium and radium. D. I. Mendeleev included magnesium in this family. Alkaline earth elements are named for the reason that their hydroxides, like alkali metal hydroxides, are soluble in water, that is, they are alkalis. “... They are called earthy because in nature they are found in the state of compounds that form an insoluble mass of the earth, and themselves, in the form of RO oxides, have an earthy appearance,” Mendeleev explained in Fundamentals of Chemistry.
General characteristics of the elements of group IIa
Metals of the main subgroup of group II have an electronic configuration of the outer energy level ns², and are s-elements.
Easily donate two valence electrons, and in all compounds they have an oxidation state of +2
Strong reducing agents
The activity of metals and their reducing ability increases in the series: Be–Mg–Ca–Sr–Ba
Alkaline earth metals include only calcium, strontium, barium and radium, less often magnesium
Beryllium is closer to aluminum in most properties.
Physical properties of simple substances
Alkaline earth metals (versus alkali metals) have higher t°pl. and t ° boiling., ionization potentials, densities and hardness.
Chemical properties of alkaline earth metals + Be
1. Reaction with water.
V normal conditions the surface of Be and Mg is covered with an inert oxide film, so they are resistant to water. In contrast, Ca, Sr and Ba dissolve in water with the formation of alkalis:
Mg + 2H 2 O - t ° → Mg (OH) 2 + H 2
Ca + 2H 2 O → Ca (OH) 2 + H 2
2. Reaction with oxygen.
All metals form oxides RO, barium peroxide - BaO 2:
2Mg + O 2 → 2MgO
Ba + O 2 → BaO 2
3. Form binary compounds with other non-metals:
Be + Cl 2 → BeCl 2 (halides)
Ba + S → BaS (sulfides)
3Mg + N 2 → Mg 3 N 2 (nitrides)
Ca + H 2 → CaH 2 (hydrides)
Ca + 2C → CaC 2 (carbides)
3Ba + 2P → Ba 3 P 2 (phosphides)
Beryllium and magnesium react relatively slowly with non-metals.
4. All alkaline earth metals dissolve in acids:
Ca + 2HCl → CaCl 2 + H 2
Mg + H 2 SO 4 (dec.) → MgSO 4 + H 2
5. Beryllium dissolves in aqueous solutions alkalis:
Be + 2NaOH + 2H 2 O → Na 2 + H 2
6. Volatile compounds alkaline earth metals give the flame its characteristic color:
calcium compounds - brick red, strontium - carmine red, and barium - yellowish green.
Beryllium, like lithium, is an s-element. The fourth electron that appears in the Be atom is placed in the 2s orbital. The ionization energy of beryllium is higher than that of lithium due to the larger nuclear charge. In strong bases, it forms the BeO 2-2 beryllate ion. Therefore, beryllium is a metal, but its compounds are amphoteric. Beryllium, although a metal, is much less electropositive than lithium.
The high ionization energy of the beryllium atom differs markedly from other elements of the PA subgroup (magnesium and alkaline earth metals). Its chemistry is largely similar to that of aluminum (diagonal similarity). Thus, this is an element with the presence of amphoteric qualities in its compounds, among which the basic ones still prevail.
The electronic configuration of Mg: 1s 2 2s 2 2p 6 3s 2 has one significant feature compared to sodium: the twelfth electron is placed in the 2s orbital, where there is already 1e - .
Magnesium and calcium ions are indispensable elements of the vital activity of any cell. Their ratio in the body must be strictly defined. Magnesium ions are involved in the activity of enzymes (for example, carboxylase), calcium - in the construction of the skeleton and metabolism. Increasing the calcium content improves the absorption of food. Calcium excites and regulates the work of the heart. Its excess sharply increases the activity of the heart. Magnesium plays part of the role of a calcium antagonist. The introduction of Mg 2+ ions under the skin causes anesthesia without a period of excitement, paralysis of muscles, nerves and heart. Getting into the wound in the form of metal, it causes long-term non-healing purulent processes. Magnesium oxide in the lungs causes the so-called foundry fever. Frequent contact of the skin surface with its compounds leads to dermatitis. The most widely used calcium salts in medicine are CaSO 4 sulfate and CaCL 2 chloride. The first is used for plaster casts, and the second is used for intravenous infusions and as an internal remedy. It helps fight swelling, inflammation, allergies, relieves spasms of the cardiovascular system, and improves blood clotting.
All barium compounds except BaSO 4 are poisonous. Cause mengoencephalitis with damage to the cerebellum, damage to smooth heart muscles, paralysis, and in large doses - degenerative changes in the liver. In small doses, barium compounds stimulate the activity of the bone marrow.
When strontium compounds are introduced into the stomach, its disorder, paralysis, and vomiting occur; lesions are similar in signs to lesions from barium salts, but strontium salts are less toxic. Of particular concern is the appearance in the body of the radioactive isotope of strontium 90 Sr. It is extremely slowly excreted from the body, and its long half-life and, therefore, the duration of action can cause radiation sickness.
Radium is dangerous for the body with its radiation and a huge half-life (T 1/2 = 1617 years). Initially, after the discovery and production of radium salts in a more or less pure form, it began to be used quite widely for fluoroscopy, the treatment of tumors, and some serious diseases. Now, with the advent of other more accessible and cheaper materials, the use of radium in medicine has practically ceased. In some cases, it is used to produce radon and as an additive to mineral fertilizers.
The filling of the 4s orbital is completed in the calcium atom. Together with potassium, it forms a pair of s-elements fourth period. Calcium hydroxide is quite strong base. In calcium - the least active of all alkaline earth metals - the nature of the bond in the compounds is ionic.
According to its characteristics, strontium occupies an intermediate position between calcium and barium.
The properties of barium are closest to those of alkali metals.
Beryllium and magnesium are widely used in alloys. Beryllium bronzes are elastic copper alloys with 0.5-3% beryllium; aviation alloys (density 1.8) contain 85-90% magnesium ("electron"). Beryllium differs from other metals of group IIA - it does not react with hydrogen and water, but it dissolves in alkalis, since it forms amphoteric hydroxide:
Be + H 2 O + 2NaOH \u003d Na 2 + H 2.
Magnesium actively reacts with nitrogen:
3 Mg + N 2 \u003d Mg 3 N 2.
The table shows the solubility of hydroxides of elements of group II.
Traditional technical problem – hardness of water associated with the presence of Mg 2+ and Ca 2+ ions in it. Magnesium and calcium carbonates and calcium sulfate are deposited on the walls of heating boilers and pipes with hot water from bicarbonates and sulfates. They especially interfere with the work of laboratory distillers.
S-elements in a living organism perform an important biological function. The table shows their content.
The extracellular fluid contains 5 times more sodium ions than inside the cells. Isotonic solution ("physiological fluid") contains 0.9% sodium chloride, it is used for injections, washing wounds and eyes, etc. Hypertonic solutions (3-10% sodium chloride) are used as lotions in the treatment of purulent wounds ("stretching » pus). 98% of potassium ions in the body are inside the cells and only 2% in the extracellular fluid. A person needs 2.5-5 g of potassium per day. 100 g of dried apricots contains up to 2 g of potassium. In 100 g of fried potatoes - up to 0.5 g of potassium. In intracellular enzymatic reactions, ATP and ADP participate in the form of magnesium complexes.
Every day a person needs 300-400 mg of magnesium. It enters the body with bread (90 mg of magnesium per 100 g of bread), cereals (in 100 g of oatmeal up to 115 mg of magnesium), nuts (up to 230 mg of magnesium per 100 g of nuts). In addition to building bones and teeth based on hydroxylapatite Ca 10 (PO 4) 6 (OH) 2, calcium cations are actively involved in blood coagulation, transmission of nerve impulses, and muscle contraction. Adults need to consume about 1 g of calcium per day. 100 g of hard cheeses contain 750 mg of calcium; in 100 g of milk - 120 mg of calcium; in 100 g of cabbage - up to 50 mg.
