SaO– calcium oxide or quicklime, obtained by the decomposition of limestone: CaCO 3 = CaO + CO 2 is an oxide of an alkaline earth metal, so it actively interacts with water: CaO + H 2 O = Ca (OH) 2
Ca(OH) 2 – calcium hydroxide or slaked lime, therefore the reaction CaO + H 2 O = Ca(OH) 2 is called slaking of lime. If the solution is filtered, the result is lime water - this is an alkali solution, so it changes the color of phenolphthalein to crimson.
Slaked lime is widely used in construction. Its mixture with sand and water is a good binding material. Under the influence of carbon dioxide, the mixture hardens Ca(OH) 2 + CO 2 = CaCO3 + H 2 O.
At the same time, part of the sand and mixture turns into silicate Ca(OH) 2 + SiO 2 = CaSiO 3 + H 2 O.
The equations Ca (OH) 2 + CO 2 = CaCO 2 + H 2 O and CaCO 3 + H 2 O + CO 2 = Ca (HCO 3) 2 play a large role in nature and in shaping the appearance of our planet. Carbon dioxide in the form of a sculptor and architect creates underground palaces in the strata of carbonate rocks. It is capable of moving hundreds and thousands of tons of limestone underground. Along cracks in rocks, water containing dissolved in it carbon dioxide, falls into the thickness of limestone, forming cavities - caster caves. Calcium bicarbonate exists only in solution. Groundwater move in the earth's crust, evaporating water under suitable conditions: Ca(HCO3) 2 = CaCO3 + H2O + CO 2 , This is how stalactites and stalagmites are formed, the formation scheme of which was proposed by the famous geochemist A.E. Fersman. There are a lot of castrum caves in Crimea. Science studies them speleology.
Calcium carbonate used in construction CaCO3- chalk, limestone, marble. You have all seen our railway station: it is decorated with white marble brought from abroad.
experience: blow through a tube into a solution of lime water, it becomes cloudy .
Ca(OH) 2 + CO 2 = CaCO 3 + N 2 ABOUT
Flows to the formed sediment acetic acid, boiling is observed, because carbon dioxide is released.
CaCO 3 +2CH 3 COOH = Ca(CH 3 SOO) 2 +H 2 O + CO 2
THE TALE OF THE CARBONATE BROTHERS.
Three brothers live on earth
From the Carbonate family.
The older brother is a handsome MARBLE,
Glorious in the name of Karara,
An excellent architect. He
Built Rome and the Parthenon.
Everyone knows LIMESTONE,
That's why it's named like that.
Famous for his work
Building a house behind the house.
Both capable and able
Little soft brother MEL.
Look how he draws,
This CaCO 3!
Brothers love to frolic
Heat in a hot oven,
CaO and CO 2 are then formed.
This is carbon dioxide
Each of you is familiar with him,
We exhale it.
Well, this is SaO -
Hot-burnt quicklime.
Add water to it,
Mix thoroughly
So that there is no trouble,
We protect our hands
Well-kneaded LIME, but SLASHED!
Lime milk
The walls are whitewashed easily.
The bright house became cheerful,
Turning lime into chalk.
Hocus Pocus for the People:
You just have to blow through the water,
How easy it is
Turned into milk!
And now it's pretty clever
I get soda:
Milk plus vinegar. Ay!
Foam is pouring over the edge!
Everything is in worries, everything is in work
From dawn to dawn -
These brothers Carbonates,
These CaCO 3!
Repetition:
CaO– calcium oxide, quicklime;
Ca(OH) 2
– calcium hydroxide (slaked lime, lime water, milk of lime depending on the concentration of the solution).
General - the same chemical formula Ca(OH) 2. Difference: lime water is a transparent saturated solution of Ca(OH) 2, and milk of lime is a white suspension of Ca(OH) 2 in water.
CaCl 2
- calcium chloride, calcium chloride;
CaCO 3
– calcium carbonate, chalk, shell marble, limestone.
L/R: collections. Next, we demonstrate a collection of minerals available in the school laboratory: limestone, chalk, marble, shell rock.
CaS0 4
∙ 2H 2
0
- calcium sulfate crystal hydrate, gypsum;
CaCO 3
- calcite, calcium carbonate is part of many minerals that cover 30 million km 2 on earth.
The most important of these minerals is limestone. Shell rocks, limestones of organic origin. It is used in the production of cement, calcium carbide, soda, all types of lime, and in metallurgy. Limestone is the basis of the construction industry; many building materials are made from it.
Chalk It's not just tooth powder and school chalk. This is also a valuable additive in the production of paper (coated - highest quality) and rubber; in construction and renovation of buildings - as whitewash.
Marble is a dense crystalline rock. There is a colored one - white, but most often various impurities color it in different colors. Clean white marble is rare and is mainly used by sculptors (statues by Michelangelo, Rodin. In construction, colored marble is used as facing material (Moscow Metro) or even as the main building material of palaces (Taj Mahal).
In the world of interesting things “Taj Mahal MAUSOLEUM”
Shah Jahan of the Great Mughal dynasty kept almost all of Asia in fear and obedience. In 1629, Mumzat Mahal, Shah Jahan's beloved wife, died at the age of 39 during childbirth on a campaign (this was their 14th child, all of them boys). She was unusually beautiful, bright, smart, the emperor obeyed her in everything. Before her death, she asked her husband to build a tomb, take care of the children, and not marry. The saddened king sent his envoys to all big cities, the capitals of neighboring states - to Bukhara, Samarkand, Baghdad, Damascus, to find and invite the best masters- in memory of his wife, the king decided to erect the best building in the world. At the same time, messengers sent plans for all the best buildings in Asia and the best building materials to Agra (India). They even brought malachite from Russia and the Urals. The chief masons came from Delhi and Kandahar; architects - from Istanbul, Samarkand; decorators - from Bukhara; gardeners - from Bengal; the artists were from Damascus and Baghdad, and the well-known master Ustad-Isa was in charge.
Together, over 25 years, a chalk marble structure was built surrounded by green gardens, blue fountains and a red sandstone mosque. 20,000 slaves erected this miracle of 75 m (25-story building). Nearby I wanted to build a second mausoleum of black marble for myself, but I didn’t have time. He was overthrown from the throne by his own son (the 2nd, and he also killed all his brothers).
The ruler and master of Agra spent the last years of his life looking out of the narrow window of his prison. For 7 years my father admired his creation. When the father went blind, the son made him a system of mirrors so that the father could admire the mausoleum. He was buried in the Taj Mahal, next to his Mumtaz.
Those entering the mausoleum see cenotaphs - false tombs. The eternal resting places of the Great Khan and his wife are located downstairs in the basement. Everything is inlaid there precious stones, which glow as if alive, and the branches fairy trees, intertwined with flowers, intricate patterns decorate the walls of the tomb. Crafted by the best carvers, turquoise-blue lapis lazuli, green-black jades and red amethysts celebrate the love of Shah Jahal and Mumzat Mahal.
Every day tourists rush to Agra, wanting to see the true wonder of the world - the Taj Mahal mausoleum, as if floating above the ground.
CaCO 3 - This construction material external skeleton of mollusks, corals, shells, etc., egg shells. (illustrations or Animals of the coral biocenosis” and display of a collection of sea corals, sponges, shell rock).
Limestone is very famous material, which is used in various areas of national industry. One of its brightest representatives is ordinary chalk, used to produce quicklime.
There are also other types of this rock, which are much stronger, which makes it possible to make facing tiles from them. This material is in great demand in the construction world, as it has unique decorative characteristics.
When choosing such products, the price of limestone tiles may vary depending on its quality.
This rock was formed by the layering of organic calcium remains of living beings. Limestone, for the most part, consists of several types of minerals:
The exact composition of such a substance depends specifically on the environmental conditions in which it was formed. For example, if we talk about dolomitized limestone, then its composition includes magnesium oxide (MgO), the percentage of which can reach 17%, while in marly limestone, on the contrary, there is a ratio of SiO2 + R3O3 in an amount from 6% to 21%.
Limestones are often named by the predominant substance in their composition. Thus, sandy rocks contain quartz, opal and chalcedony.
Limestones have a certain color scheme. The main color is white with shades of gray and yellow. There are also rocks that have a brown or reddish color, which indicates the presence of iron and manganese in its composition.
If algae also took part in the formation of limestone, then they can color it greenish. There is also black material, but these types of rocks are very rare.
The density of a given rock also varies and can differ significantly for each type of substance.
Limestone is used to make various types slabs for cladding, and it is also used for the construction of roads and other coatings. Sometimes it is used as filters for installation on special hydraulic structures.
Limestone is a unique substance that has different properties, which makes it very popular in various fields.
The video explains in detail what limestone is made of:
From a chemical point of view, chalk, marble and limestone are the same substance - calcium carbonate, or rather, one of its crystalline modifications - calcite.
Chalk- This is a soft rock that can be easily ground into powder. Chalk is used as a white pigment in the paint and varnish and rubber industries, in the production of Portland cement, and as a writing material.
Limestonehas greater hardness: it has long been used as a material for stone structures. Most of the churches of Grand Ducal Moscow were built from Myachkovo limestone, which was mined near the village of Myachkovo on the Moscow River and transported to the construction site on special ships. No wonder Moscow was called white stone in the old days. Currently, limestone serves as a valuable material in the production of cement, in metallurgy as a flux (flux in metallurgy refers to substances introduced into the charge to bind impurities, for example P 2 O 5, SiO2 , in fusible slags) and in the chemical industry in the production of soda, bleach, calcium carbide.
Chalk and limestone are sedimentary rocks formed from the remains of the shells of living organisms (primarily ancient protozoa - radiolarians and foraminifera).
Assumption Cathedral on Gorodok. Zvenigorod. Around 1399
White stone carving of the Assumption Cathedral in Gorodok.
Marble- metamorphic rock formed during the recrystallization under pressure of sedimentary carbonate rocks - mainly limestones. It also consists of calcite (calcium carbonate), however, unlike chalk and limestone, it is a coarse-crystalline material: on the surface
a piece of marble, its granular structure is clearly visible. Compared to chalk and limestone, marble is hard: it was not for nothing that the ancients built temples from it. Due to various impurities, marble is often colored; marble from some deposits has a beautiful structure in which layers of different colors alternate. In ancient times, snow-white Carrara marble, pink Parian, yellow Siena. The main temple of the Athenian Acropolis - the famous Parthenon - is built from blocks Pentelic marble, which was mined in the town of Pentelikon, northeast of Athens. Pentelic marble has a barely noticeable golden hue, which intensifies when you look at the Parthenon in the evening, at sunset. In Italy, a common type of marble is cippolino- this is the name given to white marble with small yellow or green veins. But the famous red one Veronese marble ( rosso di Verona ) is actually a brownish-red limestone in which fossils are often found.
Well, I hope everyone guessed that we're talking about about a substance, one of the modifications of which is known to us as “chalk”, and this issue is dedicated to the upcoming beginning school year- although all sorts of innovations are now coming to schools, such as white boards with markers or even interactive whiteboards, a dark board - black, brown or green - and chalk still remain the main attributes of the educational process.
Even if someone, having graduated from school, ceases his contact with the educational authorities once and for all, his hands do not stop touching the closest relative of chalk - every time we pick up an egg to peel it, we touch limestone - a form of carbonate calcium, which gives hardness eggshells and mollusk shells.
... and Carrara marble would not look after you...
So, today's wonderful substance is the many-sided potassium carbonate, existing (and known) in the form various forms. The formula of this compound is CaCO 3, it is a salt in which the calcium cation is bound by an ionic bond to the carbonate anion. This substance is quite common in nature, as a single substance it forms two minerals - calcite and aragonite, and is also the main component of such minerals as limestone, chalk and marble. The last trinity, in addition to calcium carbonate, includes its “cousin” - magnesium carbonate MgCO 3, as well as metal oxides; It is the oxides of transition metals that give marble its characteristic color - ferric oxide gives shades of red, and trivalent chromium oxide gives shades of green.
An old drawing, relevant in connection with the introduction of 4th grade course “Fundamentals of religious culture and secular ethics”
As for school crayons, the days when they consisted of almost pure chalk have sunk into oblivion. It is guaranteed that in my school childhood we wrote with almost pure chalk, which sometimes contained pieces of shells (why this is a sign of pure chalk will be literally in the next paragraph), and we loved to test the teachers’ nerves by deliberately running such a piece of shell across the board (well and I probably won’t develop this topic). Modern molded school chalk consists of 40% of chalk itself (calcium carbonate) and 60% of gypsum (this is another relative of our today’s “hero” - calcium sulfate dihydrate - CaSO 4 ˙H 2 O), and the addition to it pigments - organic or inorganic origin allows you to diversify White color school chalk, giving it color.
Chalk rocks on south coast England near the towns of Seaford and Eastbourne
Most of the currently known rocks containing calcium carbonate are of sedimentary origin - they were formed from the shells and skeletons of dead sea inhabitants, compacted as a result of the pressure of subsequent layers of sedimentary rocks. Chalk and limestone are similar materials, the difference being that chalk is less compact and for this reason softer. The formation of marble, calcite and aragonite requires longer time- the starting material for the formation of marble is limestone or chalk, which, under the influence high pressures and temperatures - conditions usual for the geological formation of minerals, are rearranged into a form with a more compact and dense crystal lattice.
Bio- (or rather, zoogenic) deposits of calcium carbonate gave the name to an entire geological period - the Cretaceous period (mile Cretaceous). This period is last period The Mesozoic era, it lasted 80 million years, began 145 million years ago, ended 65 million years ago and is most famous for the “Cretaceous catastrophe”, which resulted in a mass extinction of species - many gymnosperms, aquatic reptiles, pterosaurs, all dinosaurs died out (but survived birds). Ammonites, many brachiopods, and almost all belemnites disappeared. In the surviving groups, 30-50% of species became extinct.
One of interesting shapes The calcium carbonate mineral is clear calcite or Iceland spar. In 1669 the Danish naturalist Rasmus Bartholin at work Experimentia Crystalli Islandici Disdiaclastici described the strange property of Islan spar, now known as “birefringence.” It lies in the fact that if a ray of light falls perpendicular to the surface of the crystal, then on this surface it is split into two rays. The first ray continues to propagate straight, and is called ordinary, but the second deviates to the side, violating the usual law of light refraction, and is called extraordinary, and, accordingly, looking through a calcite crystal, we see a “double” image.
Birefringence in Iceland spar crystals has been and is used in practice, for example, for rangefinders in bomb sights, however, naturally, the use of calcium carbonate by mankind began a very long time ago.
Thus, one of the first examples " landscape design" may be considered prehistoric white horses of the British county of Wilshire, which were obtained by removing turf and fertile layer soil, exposing the underlying layer of chalk.
Calcium carbonate in the form of limestone and marble has been used since ancient times as a building material. Despite a certain softness of limestone, humanity has not abandoned them practical application- so the great pyramid of Giza, which remained the most tall building in the world, built from approximately two and a half million limestone blocks.
Again, since ancient times, calcium carbonate has given rise to another building material, although this required the first chemical production. From the time of Ancient Egypt architects knew that calcination of carbonate makes it possible to obtain slaked (or calcined) lime, the main component of which is calcium oxide CaO. Quicklime is used in binders mortars and in the manufacture of cement - on its own or after treatment with water (slaked lime or calcium hydroxide Ca (OH) 2). There are known cases of using quicklime in the defense of castles - quicklime actively interacts with water, and since the skin of a healthy person is always wet (especially if this healthy person is crawling along a siege ladder to someone else’s fortress wall), the besieged poured quicklime on the besiegers, causing skin burns to them and organs of vision.
Also, since ancient times, calcium carbonate has been used to reduce the acidity of the soil (this is also the same recipe for an amateur gardener, of which there were millions in the country of councils - throw egg shells into the soil where moss has begun to sprout- moss grows on acidic soils, and calcium carbonate, being a salt of a weak acid, reacts with the free acid of the soil, binding it).
Since the beginning of the twentieth century, calcium carbonate has been used in many industrial production in addition to the construction industry, for example, the pulp and paper industry for the production of high-quality coated paper. Calcium carbonate is used as a filler to provide additional strength polymer materials, it was used in bakery production(to increase calcium intake). Today, calcium carbonate is used in Food Industry like white food coloring(E170). Calcium carbonate was and is used in tooth powders and toothpastes, although for this purpose they use not “organic” chalk, formed from the remains of extinct species of animals, but synthetic one - for oral hygiene, calcium carbonate is obtained by passing carbon dioxide through slaked lime: Ca( OH) 2 + CO 2 = CaCO 3 + H 2 O. I don’t specifically explain why this is so, think for yourself, activating your brain at the beginning of the school year, but I suggest that the reason for this phenomenon can be found by carefully reading the post ( throw your guesses in the comments, you’re right, I won’t screen them).
Unfortunately, the fact that calcium carbonate reacts with acids has now become a whole problem for the preservation of architectural and artistic heritage - buildings and sculptures and various forms of calcium carbonate - especially from less dense limestone, although this problem also applies to marble, although it is destroyed at a lower rate, are damaged due to acid erosion caused by acid rain.
So, we can say that no substance has made such a contribution to the culture of mankind and continues to do so to this day as calcium carbonate. We can trace its path in human civilization from the first rock paintings on the walls of the cave with chalk, pyramids before school board and chalk and buildings made of glass and concrete. And, knowing how much human civilization owes to calcium carbonate, we will not be mistaken if we say that human civilization grew up on bones - the bones of a huge number of organisms that became extinct at the end of the Cretaceous period.
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An excellent example of a metamorphic rock is the well-known marble. It is widely used in our country for interior decoration buildings, for making statues and various household crafts - ink utensils, ashtrays, etc.
In its chemical composition, marble is no different from limestone, but look how different they are from each other: limestone is matte and dense; marble, especially when freshly split, reveals a fine-crystalline structure, and the edges of the smallest crystals sparkle, as in lump sugar.
In nature we can trace how limestone turns into marble. Marble lies in places where deep rocks break through limestone strata: the closer the marble is to the point of contact, otherwise - to the contact, with deep rocks, the larger its grain and the darker its color (bluish, reddish, etc.), and as it moves away from the contact the grain becomes smaller and the color becomes lighter (grayish, yellowish).
Under the influence of enormous pressure from overlying rocks, as well as in connection with mountain building processes, the clays are compacted and transformed into clay shales. They have the ability to split into thin plates upon impact, do not get wet from water and are more hard than clay. From here it is not difficult to conclude what profound changes are produced in the mineral substance (without changing it chemical composition) high temperatures and pressure.
An example of metamorphism (transformation) under the influence of solutions are breccias, conglomerates and sandstones, which we have already discussed above.
In many places of our Union, especially in Karelia, Ukraine and Transbaikalia, gray light-colored crystalline rocks that have the same mineralogical composition as granites come directly to the surface of the earth. They also include feldspar, quartz and mica, only the mica is not arranged randomly, as in granite, but in more or less distinct rows; Such rocks are called gneisses.
Between granites and thin-layered or schistose gneisses there are a number of transitions in the form of granite-gneisses.
Gneisses arose through the metamorphosis of both sedimentary and igneous rocks. In the building earth's crust gneisses play a huge role. They serve as the foundation for sedimentary rocks on such flat areas globe, such as the Great Russian Plain. And indeed, everywhere on it, at one depth or another, the drills reach the granite-gneiss bed, on which the strata of sedimentary rocks rest. Near St. Petersburg, granite-gneiss rocks were discovered at a depth of 198 meters, and near Moscow - at a depth of 1655 meters.
Mica schists occupy a significant place among metamorphic rocks. They consist mainly of mica and quartz. Mica can be light or dark. Sometimes both varieties are present in shales.
A characteristic feature of mica schists is their pronounced slate composition, which is where their name comes from - “shales”. From the admixture of feldspar, shales turn into gneisses, and if quartz predominates, into quartzites.
Rocks formed as a result of metamorphization of mainly quartz sands and sandstones, through recrystallization of grains and the cement that binds them. Quartzite is a continuous dense mass in which individual grains of sand are indistinguishable. Quartzites have significant hardness. Our Karelian quartzites, predominantly dark red, enjoy well-deserved fame as a durable building and facing material, especially beautiful when polished. Red quartzite was used in the construction of the mausoleum on Red Square in Moscow.
Ferrous quartzites, which are associated with our largest iron ore deposits - Krivoy Rog in Ukraine and the famous Kursk anomaly, are of great industrial interest. It is called an anomaly because the compass gives incorrect needle readings here.
The Kursk magnetic anomaly occupies a huge area to the southeast and south of Kursk (about 250 kilometers long and 40 kilometers wide). Metamorphic rocks have their own characteristics: they do not contain fossils, but their structure still resembles sedimentary rocks, since mineral grains are sometimes arranged in distinct rows.
We briefly reviewed the main types rocks. Highest value The structure of the earth's crust includes igneous rocks such as granites, then sedimentary rocks, especially sandstones and limestones, and metamorphic rocks such as gneisses and shales.
