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Modern methods for obtaining mineral acids. Fundamentals of mineral acid technology (using the example of sulfuric acid)

Complex substances, consisting of hydrogen atoms and an acid residue, are called mineral or not organic acids. The acid residue is oxides and non-metals combined with hydrogen. The main property of acids is the ability to form salts.

Classification

The basic formula of mineral acids is H n Ac, where Ac is the acid residue. Depending on the composition of the acid residue, two types of acids are distinguished:

  • oxygen containing oxygen;
  • oxygen-free, consisting only of hydrogen and non-metal.

The main list of inorganic acids according to type is presented in the table.

Type

Name

Formula

Oxygen

Nitrogenous

Dichrome

Iodineous

Silicon - metasilicon and orthosilicon

H 2 SiO 3 and H 4 SiO 4

Manganese

Manganese

Metaphosphoric

Arsenic

Orthophosphoric

Sulphurous

Thiosulfur

Tetrathionic

Coal

Phosphorous

Phosphorous

Chlorous

Chloride

Hypochlorous

Chrome

Cyan

Oxygen-free

Hydrofluoric (fluoric)

Hydrochloric (salt)

Hydrobromic

Hydroiodic

Hydrogen sulfide

Hydrogen cyanide

In addition, according to their properties, acids are classified according to the following criteria:

  • solubility: soluble (HNO 3, HCl) and insoluble (H 2 SiO 3);
  • volatility: volatile (H 2 S, HCl) and non-volatile (H 2 SO 4, H 3 PO 4);
  • degree of dissociation: strong (HNO 3) and weak (H 2 CO 3).

Rice. 1. Acid classification scheme.

To designate mineral acids, traditional and trivial names. Traditional names correspond to the name of the element that forms the acid with the addition of the morphemes -naya, -ovaya, as well as -istaya, -novataya, -novataya to indicate the degree of oxidation.

Receipt

The main methods for producing acids are presented in the table.

Properties

Most acids are liquids with a sour taste. Tungstic, chromic, boric and several other acids are found in solid state at normal conditions. Some acids (H 2 CO 3, H 2 SO 3, HClO) exist only in the form of an aqueous solution and are classified as weak acids.

Rice. 2. Chromic acid.

Acids - active substances, reacting:

  • with metals:

    Ca + 2HCl = CaCl 2 + H 2;

  • with oxides:

    CaO + 2HCl = CaCl 2 + H 2 O;

  • with base:

    H 2 SO 4 + 2KOH = K 2 SO 4 + 2H 2 O;

  • with salts:

    Na 2 CO 3 + 2HCl = 2NaCl + CO 2 + H 2 O.

All reactions are accompanied by the formation of salts.

Possible qualitative reaction with indicator color changing:

  • litmus turns red;
  • methyl orange - to pink;
  • phenolphthalein does not change.

Rice. 3. Colors of indicators when acid reacts.

Chemical properties mineral acids are determined by their ability to dissociate in water to form hydrogen cations and anions of hydrogen residues. Acids that react irreversibly with water (dissociate completely) are called strong. These include chlorine, nitrogen, sulfur and hydrogen chloride.

What have we learned?

Inorganic acids are formed by hydrogen and an acid residue, which is a non-metal atom or an oxide. Depending on the nature of the acid residue, acids are classified into oxygen-free and oxygen-containing. All acids have a sour taste and are capable of dissociating in an aqueous environment (breaking down into cations and anions). Acids are obtained from simple substances, oxides, and salts. When interacting with metals, oxides, bases, and salts, acids form salts.

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HClO, etc.) cannot be isolated in the form of individual compounds; they exist only in solution.

By chemical composition a distinction is made between oxygen-free acids (HCl, H 2 S, HF, HCN) and oxygen-containing acids (oxo acids) (H 2 SO 4, H 3 PO 4). The composition of oxygen-free acids can be described by the formula: H n X, where X is chemical element forming an acid (halogen, chalcogen) or an oxygen-free radical: for example, hydrobromic HBr, hydrocyanic HCN, azide HN 3 acids. In turn, everything oxygenated acids have a composition that can be expressed by the formula: H n XO m, where X is a chemical element that forms an acid.

The hydrogen atoms in oxygen-containing acids are most often linked to the oxygen by a polar covalent bond. Acids are known with several (usually two) tautomeric or isomeric forms, which differ in the position of the hydrogen atom:

Certain classes of inorganic acids form compounds in which the atoms of the acid-forming element form molecular homo- and heterogeneous chain structures. Isopolyacids are acids in which the atoms of the acid-forming element are connected through an oxygen atom (oxygen bridge). Examples are polysulfur acids H 2 S 2 O 7 and H 2 S 3 O 10 and polychromic acids H 2 Cr 2 O 7 and H 2 Cr 3 O 10 . Acids with several atoms of different acid-forming elements connected through an oxygen atom are called heteropolyacids. There are acids whose molecular structure is formed by a chain of identical acid-forming atoms, for example in polythionic acids H 2 S n O 6 or in sulfans H 2 S n, where n≥2.

texvc not found; See math/README for setup help.): \mathsf(HA + H_2O \rightleftarrows H_3O^+ + A^-) Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(HA \rightarrow H^+ + A^-)(simplified notation)
Acid Meaning
(m–n)		 K a
HClO 0 10 −8
H3AsO3 0 10 −10
H 2 SO 3 1 10 −2
N 3 PO 4 1 10 −2
HNO3 2 10 1
H2SO4 2 10 3
HClO4 3 10 10

This pattern is due to increased polarization N-O connections due to a shift in electron density from a bond to an electronegative oxygen atom along mobile π-bonds E=O and delocalization of the electron density in the anion.

Inorganic acids have properties common to all acids, including: indicator coloring, dissolution active metals with the release of hydrogen (except HNO 3), the ability to react with bases and basic oxides to form salts, for example:

Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(2HCl + Mg \rightarrow MgCl_2 + H_2\uparrow) Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(HNO_3 + NaOH \rightarrow NaNO_3 + H_2O) Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(2HCl + CaO \rightarrow CaCl_2 + H_2O)

The number of hydrogen atoms that are split off from an acid molecule and can be replaced by a metal to form a salt is called the basicity of the acid. Acids can be divided into one-, two- and three-basic. Acids with higher basicity are unknown.

Many inorganic acids are monobasic: hydrohalic acids HHal, nitric HNO 3, chloric HClO 4, hydrogen thiocyanate HSCN, etc. Sulfuric acid H 2 SO 4, chromic H 2 CrO 4, hydrogen sulfide H 2 S are examples of dibasic acids, etc.

Polybasic acids dissociate stepwise, each step has its own acidity constant, and each subsequent K a is always less than the previous one by approximately five orders of magnitude. The dissociation equations for tribasic orthophosphoric acid are shown below:

Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(H_3PO_4 \rightleftarrows H^+ + H_2PO_4^- \ \ K_(a1) = 7\cdot 10^(-3)) Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(H_2PO_4^- \rightleftarrows H^+ + HPO_4^(2-) \ \ K_(a2) = 6\cdot 10^(-8)) Unable to parse expression (Executable file texvc not found; See math/README for setup help.: \mathsf(HPO_4^(2-) \rightleftarrows H^+ + PO_4^(3-) \ \ K_(a3) = 1\cdot 10^(-12))

Basicity determines the number of rows of medium and acid salts - acid derivatives.

Only hydrogen atoms that are part of the hydroxy groups -OH are capable of substitution, therefore, for example, orthophosphoric acid H 3 PO 4 forms medium salts - phosphates of the form Na 3 PO 4, and two series of acidic ones - hydrophosphates Na 2 HPO 4 and dihydrogen phosphates NaH 2 PO 4 . Whereas, phosphorous acid H 2 (HPO 3) has only two series - phosphites and hydrophosphites, and hypophosphorous acid H (H 2 PO 2) - only a series of middle salts - hypophosphites.

General methods for producing acids

There are many methods for producing acids, including general ones, among which in industrial and laboratory practice the following can be distinguished:

  • Interaction of acid oxides (anhydrides) with water, for example:
Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(P_2O_5 + 3H_2O \rightarrow 2H_3PO_4) Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(2CrO_3 + H_2O \rightarrow H_2Cr_2O_7)
  • Displacement of a more volatile acid from its salt by a less volatile acid, for example:
Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(CaF_2 + H_2SO_4 \rightarrow CaSO_4 + 2HF\uparrow) Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(KNO_3 + H_2SO_4 \rightarrow KHSO_4 + HNO_3\uparrow)
  • Hydrolysis of halides or salts, for example:
Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(PCl_5 + 4H_2O \rightarrow H_3PO_4 + 5HCl) Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(Al_2Se_3 + 6H_2O \rightarrow 2Al(OH)_3 + 3H_2Se)
  • Synthesis of oxygen-free acids from simple substances
Unable to parse expression (Executable file texvc not found; See math/README for setup help.): \mathsf(H_2 + Cl_2 \rightarrow 2HCl)
  • Ion exchange reactions on the surface of ion exchange resins: chemisorption of cations of dissolved salts and their replacement with H +.

Application

Mineral acids are widely used in metal and woodworking, textile, paint and varnish, oil and gas and other industries and in scientific research. The substances produced in the largest volumes include sulfuric, nitric, phosphoric, and hydrochloric acids. The total annual production of these acids in the world amounts to hundreds of millions of tons per year.

In metalworking, they are often used for pickling iron and steel and as cleaning agents before welding, plating, painting or galvanizing.

Sulfuric acid, aptly named by D. I. Mendeleev “ bread industry", used in the production of mineral fertilizers, for the production of other mineral acids and salts, in the production of chemical fibers, dyes, smoke-forming and explosives, in the oil, metalworking, textile, leather, food and other industries, in industrial organic synthesis, etc.

Hydrochloric acid is used for acid treatment, purification of tin and tantalum ores, for the production of molasses from starch, for descaling from boilers and heat exchange equipment of thermal power plants. It is also used as a tanning agent in the leather industry.

Nitric acid is used in the production of ammonium nitrate, which is used as a fertilizer and in the production of explosives. In addition, it is used in organic synthesis processes, metallurgy, ore flotation and for the reprocessing of spent nuclear fuel.

Orthophosphoric acid is widely used in the production of mineral fertilizers. It is used in soldering as a flux (on oxidized copper, on ferrous metal, on stainless steel). Included in corrosion inhibitors. It is also used in the composition of freons in industrial freezing units as a binder.

Peroxoacids, oxygen-containing acids of chlorine, manganese, and chromium are used as strong oxidizing agents.

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Literature

  1. Nekrasov B.V., Fundamentals of General Chemistry, 3rd ed., vol. 1-2. M., 1973;
  2. Campbell J., Modern general chemistry, trans. from English, vol. 1-3, M., 1975;
  3. Bell R., Proton in Chemistry, trans. from English, M., 1977;
  4. Hyun D., Inorganic chemistry, trans. from English, M., 1987.

see also

Notes


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Inorganic acids

An excerpt characterizing inorganic acids

The same little man, Hugues de Arcy, stopped in front of the Cathars. Impatiently marking time, apparently wanting to finish as quickly as possible, he began the selection in a hoarse, cracked voice...
- What is your name?
“Esclarmonde de Pereil,” came the answer.
- Hugues de Arcy, acting on behalf of the King of France. You are accused of heresy in Qatar. You know, in accordance with our agreement, which you accepted 15 days ago, in order to be free and save your life, you must renounce your faith and sincerely swear allegiance to the faith of the Roman Catholic Church. You must say: “I renounce my religion and accept the Catholic religion!”
“I believe in my religion and will never renounce it...” was the firm answer.
- Throw her into the fire! – the little man shouted contentedly.
OK it's all over Now. Her fragile and short life came to its terrible conclusion. Two people grabbed her and threw her onto a wooden tower, on which a gloomy, emotionless “performer” was waiting, holding thick ropes in his hands. There was a fire burning there... Esclarmonde was seriously hurt, but then she smiled bitterly to herself - very soon she would have much more pain...
- What is your name? – Arcee’s survey continued.
- Corba de Pereil...
A short moment later, her poor mother was thrown just as roughly next to her.
So, one after another, the Cathars passed the “selection”, and the number of those sentenced kept increasing... All of them could save their lives. All you had to do was lie and renounce what you believed. But no one agreed to pay such a price...
The flames of the fire cracked and hissed - the damp wood did not want to burn at full power. But the wind grew stronger and from time to time brought burning tongues of fire to one of the condemned. The clothes on the unfortunate man flared up, turning the person into a burning torch... Screams were heard - apparently, not everyone could endure such pain.

Esclarmonde was trembling from cold and fear... No matter how brave she was, the sight of her burning friends gave her a real shock... She was completely exhausted and unhappy. She really wanted to call someone for help... But she knew for sure that no one would help or come.
Little Vidomir appeared before my eyes. She will never see him grow... will never know if his life will be happy. She was a mother who hugged her child just once, for a moment... And she would never give birth to Svetozar’s other children, because her life was ending right now, on this bonfire... next to others.
Esclarmonde took a deep breath, ignoring the freezing cold. What a pity that there was no sun!.. She loved to bask under its gentle rays!.. But that day the sky was gloomy, gray and heavy. It said goodbye to them...
Somehow holding back the bitter tears that were ready to flow, Esclarmonde raised her head high. She will never show how bad she really felt!.. No way!!! She'll endure it somehow. The wait wasn't that long...
The mother was nearby. And just about ready to burst into flames...
Father stood like a stone statue, looking at both of them, and there was not a single drop of blood in his frozen face... It seemed as if life had left him, rushing away to where they would very soon go too.
A heart-rending scream was heard nearby - it was my mother who burst into flames...
- Korba! Korba, forgive me!!! – it was the father who shouted.
Suddenly Esclarmonde felt a gentle, affectionate touch... She knew that it was the Light of her Dawn. Svetozar... It was he who extended his hand from afar to say the last “goodbye”... To say that he was with her, that he knew how scared and painful she would be... He asked her to be strong...
A wild, sharp pain slashed through the body - here it is! It's here!!! A burning, roaring flame touched his face. Her hair flared up... A second later her body was in full flame... A sweet, bright girl, almost a child, accepted her death in silence. For some time she still heard her father screaming wildly, calling her name. Then everything disappeared... Her pure soul went into a kind and correct world. Without giving up and without breaking. Exactly the way she wanted.
Suddenly, completely out of place, singing was heard... It was the clergy present at the execution who began to sing in order to drown out the screams of the burning “convicts.” With voices hoarse from the cold, they sang psalms about the forgiveness and kindness of the Lord...
Finally, evening came at the walls of Montsegur.
The terrible fire was burning out, sometimes still flaring up in the wind as dying red coals. During the day the wind had strengthened and was now raging at full speed, carrying black clouds of soot and burning throughout the valley, seasoned with the sweetish smell of burnt human flesh...
At the funeral pyre, bumping into those nearby, a strange, detached man wandered lostly... From time to time, screaming out someone's name, he suddenly grabbed his head and began to sob loudly, heartbreakingly. The crowd surrounding him parted, respecting the grief of others. And the man again walked slowly, not seeing or noticing anything... He was gray-haired, hunched over and tired. Sharp gusts of wind blew his long gray hair, tore his thin dark clothes from his body... For a moment the man turned around and - oh, gods!.. He was still very young!!! His haggard, thin face was breathing with pain... And his wide-open gray eyes looked in surprise, seemingly not understanding where and why he was. Suddenly the man screamed wildly and... threw himself straight into the fire!.. Or rather, into what was left of him... People standing nearby tried to grab his hand, but did not have time. The man fell prostrate on the dying red coals, clutching something colored to his chest...
And he didn't breathe.
Finally, having somehow dragged him away from the fire, those around him saw what he was holding, tightly clutched in his thin, frozen fist... It was a bright hair ribbon, the kind that young Occitan brides wore before their wedding... Which meant - everything just a few hours ago he was still a happy young groom...
The wind still disturbed his long hair that had turned gray during the day, quietly playing in the burnt strands... But the man no longer felt or heard anything. Having found his beloved again, he walked with her hand in hand along the sparkling starry road of Qatar, meeting their new stellar future... He was again very happy.
Still wandering around the dying fire, people with faces frozen in grief were looking for the remains of their relatives and friends... Also, not feeling the piercing wind and cold, they rolled out the burnt bones of their sons, daughters, sisters and brothers, wives and husbands from the ashes. ... Or even just friends... From time to time, someone would cry and pick up a ring blackened in the fire... a half-burnt shoe... and even the head of a doll, which, having rolled to the side, did not have time to burn completely...
The same little man, Hugues de Arcy, was very pleased. It was finally over - the Qatari heretics were dead. Now he could safely go home. Shouting to the frozen knight on guard to bring his horse, Arcee turned to the warriors sitting by the fire to give them his final orders. His mood was joyful and upbeat - the mission, which had lasted for many months, had finally come to a “happy” end... His duty was fulfilled. And he could honestly be proud of himself. A short moment later, the rapid clatter of horse hooves could be heard in the distance - the seneschal of the city of Carcassonne was hurrying home, where a hearty hot dinner and a warm fireplace awaited him to warm his frozen, road-weary body.
On high mountain Montsegur heard the loud and sorrowful crying of eagles - they were seeing off their faithful friends and owners on their last journey... The eagles were crying very loudly... In the village of Montsegur, people fearfully closed their doors. The cry of the eagles echoed throughout the valley. They were mourning...

The terrible end of the wonderful empire of Qatar - the empire of Light and Love, Goodness and Knowledge - has come to its end...
Somewhere in the depths of the Occitan mountains there were still fugitive Cathars. They hid with their families in the Lombriv and Ornolak caves, unable to decide what to do next... Having lost the last Perfects, they felt like children who no longer had support.
They were persecuted.
They were game, for the capture of which large rewards were given.

And yet, the Cathars did not give up yet... Having moved to the caves, they felt at home there. They knew every turn there, every crevice, so it was almost impossible to track them. Although the servants of the king and the church tried their best, hoping for the promised rewards. They wandered around the caves, not knowing exactly where they should look. They got lost and died... And some of the lost ones went crazy, unable to find their way back to the open and familiar sunny world...
The pursuers were especially afraid of the Sakani cave - it ended in six separate passages, zigzags leading straight down. Nobody knew the real depth of these moves. There were legends that one of those passages led straight to the underground city of the Gods, into which not a single person dared to descend.
After waiting a little, Dad became furious. The Cathars did not want to disappear!.. This small group of exhausted and incomprehensible people did not give up!.. Despite the losses, despite the hardships, despite everything - they still LIVED. And Dad was afraid of them... He didn’t understand them. What motivated these strange, proud, unapproachable people?! Why didn’t they give up, seeing that they had no chance of salvation?.. Dad wanted them to disappear. So that not a single damned Qatar remains on earth!.. Unable to think of anything better, he ordered hordes of dogs to be sent to the caves...
The knights came to life. Now everything seemed simple and easy - they didn’t have to come up with plans to catch the “infidels.” They went into the caves “armed” with dozens of trained hunting dogs, which were supposed to lead them to the very heart of the refuge of the Qatari fugitives. Everything was simple. All that was left was to wait a little. Compared to the siege of Montsegur, this was a trifle...
The caves welcomed Qatar, opening their dark, damp arms for them... The life of the fugitives became difficult and lonely. Rather, it looked like survival... Although there were still very, very many people willing to help the fugitives. In the small towns of Occitania, such as the principality of de Foix, Castellum de Verdunum and others, the Cathars still lived under the cover of local lords. Only now they no longer gathered openly, trying to be more careful, because the Pope’s bloodhounds did not agree to calm down, wanting at all costs to exterminate this Occitan “heresy” that was hiding throughout the country...
“Be diligent in exterminating heresy by any means! God will inspire you! – the Pope’s call to the crusaders sounded. And the church messengers really tried...
- Tell me, Sever, of those who went into the caves, did anyone live to see the day when it was possible to go to the surface without fear? Did anyone manage to save their life?
– Unfortunately, no, Isidora. The Montsegur Cathars did not survive... Although, as I just told you, there were other Cathars who existed in Occitania for quite a long time. Only a century later the last Qatar was destroyed there. But their life was completely different, much more secretive and dangerous. People frightened by the Inquisition betrayed them, wanting to save their lives. Therefore, some of the remaining Katar moved to the caves. Someone settled in the forests. But that was later, and they were much more prepared for such a life. Those whose relatives and friends died in Montsegur did not want to live long with their pain... Deeply grieving for the dead, tired of hatred and persecution, they finally decided to reunite with them in that other, much kinder and purer life . There were about five hundred of them, including several old people and children. And with them were four Perfect Ones, who came to the rescue from a neighboring town.
On the night of their voluntary “departure” from the unjust and evil material world, all the Cathars went outside to last time breathe in the wonderful spring air to once again look at the familiar glow of the distant stars they love so much... where their tired, exhausted Qatari soul will fly away very soon.
The night was gentle, quiet and warm. The earth was fragrant with the smells of acacias, blossoming cherries and thyme... People inhaled the intoxicating aroma, experiencing real childhood pleasure!.. For almost three long months they did not see the clear night sky, did not breathe real air. After all, in spite of everything, no matter what happened on it, it was their land!.. Their native and beloved Occitania. Only now it was filled with hordes of the Devil, from which there was no escape.
Without saying a word, the Cathars turned to Montsegur. They wanted to take one last look at their HOME. To the Temple of the Sun, sacred to each of them. A strange, long procession of thin, emaciated people unexpectedly easily ascended to the highest of Qatari castles. It was as if nature itself was helping them!.. Or perhaps these were the souls of those with whom they were going to meet very soon?
At the foot of Montsegur a small part of the Crusader army was located. Apparently, the holy fathers were still afraid that the crazy Cathars might return. And they were guarding... The sad column passed like quiet ghosts next to the sleeping guards - no one even moved...
– They used “blackout”, right? – I asked in surprise. – Did all the Cathars know how to do this?..
- No, Isidora. “You forgot that the Perfect Ones were with them,” answered the North and calmly continued.
Having reached the top, the people stopped. In the light of the moon, the ruins of Montsegur looked ominous and unusual. It was as if every stone, soaked in the blood and pain of the dead Qatar, called for revenge on those who had come again... And although there was dead silence around, it seemed to people that they could still hear the dying cries of their relatives and friends, burning in the flames of the terrifying “cleansing” papal bonfire . Montsegur towered over them, menacing and... unnecessary to anyone, like a wounded animal left to die alone...
The walls of the castle still remembered Svetodar and Magdalena, the children's laughter of Beloyar and golden-haired Vesta... The castle remembered wonderful years Qatar, filled with joy and love. I remembered the kind and bright people who came here under his protection. Now this was no longer the case. The walls stood bare and alien, as if Kathar and the big, kind soul of Montsegur had flown away along with the souls of those burned...

The Cathars looked at the familiar stars - from here they seemed so big and close!.. And they knew that very soon these stars would become their new Home. And the stars looked down on their lost children and smiled tenderly, preparing to receive their lonely souls.
The next morning, all the Cathars gathered in a huge, low cave, which was located directly above their beloved - “cathedral”... There, once upon a time, Golden Maria taught KNOWLEDGE... New Perfects gathered there... There the Light and Good World Qatar.
And now, when they returned here only as “shards” of this wonderful world, they wanted to be closer to the past, which was no longer possible to return... The Perfect Ones quietly gave Purification (consolementum) to each of those present, affectionately laying their magic hands on their tired ones , drooping heads. Until all those “leaving” were finally ready.
In complete silence, people took turns lying down directly on the stone floor, crossing their thin arms over their chests, and completely calmly closing their eyes, as if they were just getting ready for bed... Mothers hugged their children to themselves, not wanting to part with them. A moment later, the entire huge hall turned into a quiet tomb of five hundred who had fallen asleep forever. good people...Qatar. Faithful and Bright followers of Radomir and Magdalena.
Their souls flew away together to where their proud, brave “brothers” were waiting. Where the world was gentle and kind. Where you no longer had to be afraid that, by someone’s evil, bloodthirsty will, your throat would be cut or simply thrown into the “cleansing” papal fire.
A sharp pain squeezed my heart... Tears flowed in hot streams down my cheeks, but I didn’t even notice them. Bright, beautiful and pure people have passed away... by at will. They left so as not to surrender to the killers. To leave the way they wanted. In order not to drag out a miserable, wandering life in your own proud and native land- Occitania.
– Why did they do this, Sever? Why didn't they fight?..
– We fought – with what, Isidora? Their battle was completely lost. They simply chose HOW they wanted to leave.
– But they committed suicide!.. Isn’t this punishable by karma? Didn’t this make them suffer the same way there, in that other world?
- No, Isidora... They just “left”, taking them out of physical body your souls. And this is the most natural process. They did not use violence. They just "gone away."
With deep sadness I looked at this terrible tomb, in the cold, perfect silence of which the falling drops rang from time to time. It was nature that began to slowly create its eternal shroud - a tribute to the dead... So, over the years, drop by drop, each body will gradually turn into a stone tomb, not allowing anyone to mock the dead...

Hydrochloric acid. Hydrochloric acid (HC1) belongs to the group of inorganic acids.

Pure hydrochloric acid is a colorless liquid with a sharp, irritating chlorine odor; its specific gravity at a temperature of 15° is 1.1; it releases hydrogen chloride in air and is called fuming acid.

Hydrogen chloride is a gas that is highly soluble in water: 503 volumes of hydrogen chloride can dissolve in one volume of water at a temperature of 0°.

Hydrochloric acid is used in the production of various salts, in the metallurgical industry, in the mining of gold, silver and platinum, in laboratory practice and in medicine.

In denture technology, hydrochloric acid is used to bleach gold in the manufacture of crowns. A solution of hydrochloric acid and nitric acid is used to bleach stainless steel.

Hydrochloric acid, if handled improperly, can have a harmful effect on the body. When inhaling acid vapors, inflammatory processes in the nasal mucosa can develop. Work with acid in a fume hood.

Hydrochloric acid must be stored in glass containers with a ground-in stopper; it must not be stored together with instruments and dental materials.

Nitric acid. Nitric acid (НО3) belongs to inorganic acids. In its pure form, it is a colorless liquid that fumes in air and has a pungent, irritating odor.

Its specific gravity is 1.56, boiling point 86°. Hardening at a temperature of 41.3°.

Technical nitric acid contains 68% pure nitric acid and has a yellowish color due to its partial decomposition under the influence of light during storage. When acid decomposes, nitrogen dioxide is formed.

Nitric acid is a very active acid, dissolving almost all metals except gold and platinum.

In industry, nitric acid is used for the production of nitrogenous fertilizers, explosives, medicines, dyes, etc.

In dental prosthetic technology, nitric acid is used in aqua regia to dissolve gold and platinum during refining, and is included in the bleaching agent for stainless steel.

Pure nitric acid can be used to separate gold from an alloy (quartering method).

Sulfuric acid. Sulfuric acid (H2SO4) is a chemical compound of sulfuric anhydride S0

with water N

Pure sulfuric acid is a colorless, oily liquid. Its specific gravity is 1.84, boils at a temperature of 338°, and has slight volatility.

Sulfuric acid greedily combines with water, generating a large amount of heat and absorbs moisture from the air. This ability should be taken into account when preparing solutions of sulfuric acid. When preparing the desired solution, the acid is added to the water gradually. You cannot pour water into acid, as this will cause a violent reaction that will cause the acid to splash out.

The properties of sulfuric acid to actively adsorb moisture from the air are used to dry rooms. For the winter, place a vessel with sulfuric acid in the window openings so that the glass does not fog up or become covered with an ice crust.

Sulfuric acid is obtained from sulfuric anhydride. First, sulfur dioxide, or sulfur dioxide, is produced. Sulfur dioxide can be produced by burning sulfur or heating iron ore containing sulfur (sulfur pyrite FeS

), during the metal smelting process.

In industry, in the process of metal mining, sulfur dioxide is a by-product; it is used to produce sulfuric acid.

Sulfuric acid is widely used in industry for the production of copper, zinc, nickel, silver,

MINERAL ACID

MINERAL ACID, a strong inorganic acid, such as hydrochloric (HCl), NITRIC (HNO 3) or SULFURIC ACID (H 2 SO 4).


Scientific and technical encyclopedic dictionary.

See what "MINERAL ACID" is in other dictionaries:

    mineral acid- inorganic acid...

    Caustic mineral acid HN03; in concentrated form can cause severe skin burns. Ingestion of acid leads to sharp burning pain and ulceration of the mouth, pharynx, esophagus and stomach. For treatment immediately... ... Medical terms

    NITRIC ACID- (nitric acid) caustic mineral acid HN03; in concentrated form can cause severe skin burns. Ingestion of acid leads to sharp burning pain and ulceration of the mouth, pharynx, esophagus and stomach. For treatment... ... Dictionary in medicine

    Mineral water water containing dissolved salts, microelements, as well as some biologically active components. Among mineral waters, natural mineral waters are distinguished drinking water, mineral waters for outdoor ... ... Wikipedia

    inorganic acid- mineral acid... Dictionary of chemical synonyms I

    GOST 4640-93: Mineral wool. Specifications- Terminology GOST 4640 93: Mineral wool. Technical specifications original document: 7.2 Determination of water resistance (pH) 7.2.1 Apparatus, equipment, reagents Chamber electric furnace, providing heating temperatures up to 600°C and automatic... ... Dictionary-reference book of terms of normative and technical documentation

    General... Wikipedia

    MINERAL, mineral, mineral. 1. adj. to mineral. Mineral acid. Mineral wealth of the USSR. Mineral kingdom. 2. Contains minerals. Mineral water. Mineral spring. Mineral salt. || Extracted from minerals... ... Ushakov's Explanatory Dictionary

    Asian, or Indian (cholera asiatica, ch. indica), is an acute contagious contagious disease. As can be seen from the name, X.’s homeland is Asia; here it dominates endemically in Bengal on the lower reaches of the Ganges and Brahmaputra;... ...

    The general name usually applied to all those chemicals. reactions in which water is added. These reactions are extremely numerous and varied, occur everywhere in nature and are constantly used in the laboratory... ... encyclopedic Dictionary F. Brockhaus and I.A. Ephron

There are no mineral acids and alkalis in diesel fuel produced by industrial plants. They are also not formed during storage. The only source of acids and alkalis in fuel is accidental entry into storage or transportation means or incomplete flushing of these means after repair or cleaning with inorganic solutions. [...]

Fatty acids are converted into soap with sodium hydroxide solution. The latter are separated from unsaponifiable substances by precipitation, and sometimes by a mixture of propyl and butyl alcohols. Fatty acids are separated from the soap solution with mineral acid and then salted out. Their purification is carried out by fractional vacuum distillation. An acidic salt solution containing residues of propyl and butyl alcohols forms highly contaminated wastewater. This wastewater consists mainly of paraffin oxidation products, such as alcohols, ketones and fatty acids. Since they are insoluble and their specific gravity is less than the weight of water, they can be separated in traps.[...]

Humic acids are compounds that are washed out of the soil by alkalis, phosphoric acid, oxalate or sodium fluoride and other solvents and precipitated from the resulting solutions by mineral acids in the form of a dark brown precipitate.[...]

Crown orange dissolves completely in alkalis and mineral acids, and partially dissolves in acetic acid. Orange crown consists of particles crystallizing in a tetragonal system and has high anti-corrosion properties due to its passivating (oxidizing) effect on metal (iron). Despite the presence of the PbO group in its composition, it is not capable of a soap formation reaction with oil.[...]

When acidified with mineral acids, terpine hydrate dehydrates (splits off water) and turns into a mixture of three isomeric terpineols a, 3 and -[, known as “commercial” terpineol. All isomeric terpineols have a pleasant odor, which is why they are widely used in the perfume industry.[...]

In this case, mineral acid is released in an amount equivalent to the ammonium salts present in the sample. The acid is titrated with NaOH, the titer of which corresponds to 1 mg of nitrogen ammonium salts. When preparing a sample for precipitation of carbon dioxide salts, BaCL is added.[...]

The ability of strong mineral acids to dissolve cellulose is explained by the formation of addition products, with the exception of nitric acid, which forms esters. He believes that when using phosphoric acid, a compound is formed (C6Hu03 2Hu - H3PO 4.)„. However, when cellulose is precipitated from solution, the acid can be completely washed off. Stam and Cohen were unable to dissolve degraded cellulose in 100% phosphoric acid without adding water. Ekenstam, Stamm and Cohen showed that cellulose dissolves very quickly in phosphoric acid if it is first converted to its hydrate form.[...]

Wastewater containing mineral acids or alkalis is neutralized before being discharged into water bodies or before being used in technological processes. Waters with pH = 6.5-8.5 should be considered practically neutral. [...]

Therefore, after isomerization (for example, after the action of HO on molten resin), the mixture of acids will consist only of abietic acid and dextropimaric acid, which has not undergone isomerization. [...]

We proposed to determine volatile fatty acids by steam distillation, the advantage of which is that the volume of the distillation mixture remains constant all the time, and therefore eliminates the possibility of hydrochloric acid and other volatile mineral acids getting into the distillate and eliminates the hydrolysis of complex organic compounds.[ ...]

Lignin reacts very easily with nitric acid (even dilute), which was often used to isolate cellulose fiber. In this process, lignin is completely broken down into water-soluble products. Rutala and Sevon studied the effect of nitric acid on protolignin in spruce wood and found that about 30% of the acid (based on wood) was absorbed, with 57.8% being organically bound, and the remainder being regenerated as 23.5% nitrogen, 5. 5% nitric oxide, 9.35% ammonia and 2.92% hydrogen cyanide. About 25% of the nitrated lignin was dissolved, but only a small amount of a yellow amorphous product was obtained from the aqueous filtrate. Extraction of the remaining wood with alkali produced a dark brown solution, from which, after acidification with a mineral acid, a brown flocculent product resembling nitrogen-containing alkali lignin precipitated. It dissolved in sodium carbonate to release carbon dioxide. The nitrogen content of the product has not been determined.[...]

Caustic, carbonic and bicarbonate alkalis are used as reagents for neutralizing mineral acids; the cheapest of them are Ca(OH)g in the form of fluff or lime milk and calcium and magnesium carbonates in the form of crushed chalk, limestone and dolomite. Caustic soda and soda are used to neutralize wastewater only in cases where these products are local waste.[...]

Well-known preservatives are preparations of mineral acids - sodium nitrite and sodium pyrosulfate. These preparations give a good preservative effect: when added to all types of plant feed in doses of 0.5-1.5% (wt.), when preserving feed, the loss of dry matter and other nutrients is reduced by 2-3 times compared to the usual method blanks. To preserve nutrients in straw, ammonia water, anhydrous ammonia, alkalis, etc. are widely used[...]

Wastewater from many industries contains free mineral acids: most often sulfuric, then hydrochloric (for example, in effluents of organochlorine synthesis), a mixture of sulfuric and nitric acids (in effluents of organic synthesis), less often phosphoric and phosphorous acids.[...]

Saponification catalysts esters Cellulose serves as an acid and a base. Saponification of cellulose esters and lower carboxylic acids catalyzed by mineral acids is reversible reaction. In addition to the usual method of saponification of cellulose acetate by treating with aqueous acetic acid in the presence of sulfuric acid, it is proposed to carry out this process in media containing various organic solvents: acetate, benzene, dioxane, ethanol, trichloroethane. It is assumed that these solvents make the structure of cellulose acetate more permeable to the saponifier acid solution. Turner carried out partial saponification of cellulose acetates by heating them at 180 ° C and above in alcohol (methanol, ethanol, ethylene glycol) under pressure. At these temperatures, cellulose ethers dissolved. Heating was continued until the required reduction in SZ was achieved A study of the kinetics of saponification of cellulose acetate in the temperature range of 23-95 ° C and at pH values ​​from 2 to 10 was carried out in the work of Boca et al.. The results obtained by him show that this reaction, apparently occurring in a homogeneous medium, has a pseudo -first order.[...]

Many methods of decomposition and leaching of aluminum ores with mineral acids are due to the different mineralogical composition of these ores. Thus, natural raw kaolinite and alunite in acids at atmospheric pressure decompose extremely slowly, and those fired at 500-700 ° C quite quickly and completely. Under autoclave conditions (>150°C), raw kaolinite and alunite quickly interact with solutions of all mineral acids. Nepheline reacts well with acids in the cold, while nepheline syenites and feldspars react only at high temperatures under autoclave conditions.[...]

Solutions of mineral acids (sulfuric, hydrochloric), salt bases, organic solvents, and water are most often used as regenerating agents. Any type of ion exchanger - granular, fibrous, etc. - can be subjected to chemical regeneration. Methods for chemical regeneration of ion exchangers are given in table. 48.[...]

The high efficiency of acidification of soda solonetzes with spent sulfuric acid has been noted in all regions of their distribution. Sulfuric acid and other waste mineral acids are fast-acting ameliorants.[...]

Scandium oxide is an amorphous white powder, 7’pl 1539° C. Insoluble in water, soluble in mineral acids, does not interact with alkalis. The physical state in the air is aerosol. .[...]

The process of converting carbonate hardness into non-carbonate hardness by adding mineral acid to water is called impregnation (from the German impfen - add).[...]

To decompose sodium silicates, substances are used that displace weak silicic acid from its salt - mineral acids (HC1, H2504, etc.), carbon and sulfur dioxides (CO2, BSb), acid salts (NaHSO4, NaHBO3, NaHCO3), as well as salts , forming acids during hydrolysis [Na251P6, Al2(504)3, AlCl3, FeCl3, Fe504, (MH4)2504, etc.]. Chlorine and ion exchange resins can be successfully used as an activator for the decomposition of liquid glass; promotes decomposition and electrolysis.[...]

Severely aggressive waters include: wastewater from metal pickling, containing metal acids and sulfates; water from electroplating shops contaminated with acids and salts; water from the production of mineral acids and nitroproducts; waters from some oil refinery shops containing hydrogen sulfide, acids and sulfur dioxide. Some types of wastewater from ferrous metallurgy plants are also aggressive, in particular water from slag granulation containing hydrogen sulfide and sulfates; wastewater from coke plants and gas generating stations containing organic acids and hydrogen sulfide; acidic waters of sulphite pulp mills, etc.[...]

Chemical properties. It is stable under normal storage conditions, but quickly hydrolyzes under the influence of mineral acids and alkalis at high temperatures.[...]

Neutralization installations are mandatory for all enterprises whose wastewater contains mineral acids and their salts. The main reagent for neutralizing acids in wastewater is slaked lime (usually in the form of milk of lime with an active lime content of 5-10%). When the active reaction of acid waste is brought to pH = 8 -9, the acids contained in them are neutralized and iron and metals are released in the form of insoluble hydroxides. [...]

In Fig. 6.9 shows a diagram of the installation for fire neutralization of waste with quasi-dry gas purification from gaseous mineral acids and their anhydrides, described in Section. 6.1. The exhaust gases from the fire reactor 1 are sent to the spray dryer-absorber 2, where upon contact of drops of an alkaline solution with acids and their anhydrides, they are neutralized. Sawing the alkaline solution is possible with nozzles or disk sprayers. Part of the coarse dust contained in the exhaust gases and coarse particles of the resulting salts fall into the collection of the absorber dryer. Gas purification from fine dust is carried out in electric precipitator 3. In the scheme under consideration, the captured entrainment of exhaust gases is mixed with mineral salts formed in the absorber dryer. The use of the scheme is advisable in cases where the captured dust is not a useful product and when the formation of secondary wastewater is undesirable.[...]

These lignins are called acidic because they are produced by the action of strong mineral acids (sulfuric or hydrochloric) on lignified plant material. Isolation by sulfuric acid is based on the discovery of Braconneau and Payen, who found that cellulose is hydrolyzed by this acid. However, Klason was the first to isolate lignin in this way, and therefore the lignin obtained in this way is called Klason lignin, or sulfuric acid lignin. In his original process, Klason used 72% acid, but later changed the concentration of the acid, weakening it somewhat. His method is as follows: for every 1-1.3 g of crushed wood, previously extracted and dried at a temperature of 100°, 15 cm3 of 66% sulfuric acid is added, and the mixture is stirred until foamy gelatinization. The mixture is left at a temperature of 20° for 48 hours. with periodic stirring and then diluted with water. The resulting lignin is filtered and washed until the filtrate is almost free of acid. The lignin is then suspended in 0.5% hydrochloric acid and heated in a boiling water bath for 12 hours. to remove all bound sulfuric acid and hydrolyze the remaining pentosans. The lignin is again filtered, washed from acid and dried.[...]

The determination is based on the binding of ammonia with formalin in organic compound hexamethylenetetramine. Ammonia fertilizers release mineral acid in an amount equivalent to ammonia nitrogen in the sample being analyzed. Based on the amount of acid formed, which is taken into account by titration with alkali, the nitrogen content in the fertilizer is determined.[...]

One of the most expressive examples of the differentiating and leveling effect of solvents on the strength of electrolytes dissolved in them can be a comparison of the strength of mineral acids in water and anhydrous acetic acid.[...]

Niobium is a gray metal with high ductility, Tkia 4840° C, Tm 2470° C, density 8.6 g/cm3, very resistant to various chemical influences, insoluble in mineral acids and their mixtures (with the exception of hydrofluoric acid). It may be present in the air of the work area in the form of an aerosol.[...]

The wastewater from these industries includes the following main groups of chemical compounds: unsaturated hydrocarbons, alcohols, ethers, aldehydes, ketones, organic and mineral acids and aromatic compounds. In addition, “the wastewater from some industries contains nekal, salts of heavy metals, and resins; the common wastewater of all enterprises contains latex and rubber crumbs. As many years of experience have shown, water containing large amounts of organic matter only to a small extent can they be purified by physicochemical (and expensive) methods. The most rational cleaning method is biochemical.[...]

Technological diagrams of installations for waste disposal of group V. A special feature of these installations is the need to purify the exhaust gases not only from dust, but also from gaseous mineral acids and their anhydrides.[...]

There may be various methods to carry out the reaction of formaldehyde with cellulose. The most significant of them are the interaction of formaldehyde and cellulose in the presence of strong mineral acids in an aqueous medium and the interaction of formaldehyde vapor with cellulose in the presence of catalysts (mineral acids, salts).[...]

The water hardness given in the analyzes is determined by the presence of alkaline earth metal salts. Total hardness consists of removable, or carbonate, and permanent hardness (alkaline earth salts of mineral acids and water-soluble carbonates of magnesium and partially calcium).[...]

Poorly soluble in water, alcohols, acetone, aromatic hydrocarbons. Dissolves in aqueous solutions of mineral acids and alkalis.[...]

Although numerous studies have been carried out on the oxidation of cellulose with alkaline, neutral and acidic hypochlorite, hypobromite, hydrogen peroxide, ozone, permanganate, oxygen and alkali, nitric acid, sulfurous acid at 150° and other agents, the results did not provide sufficient insight into the detailed structure of the resulting at the same time products. Many of these, when boiled with mineral acid, yield the largest quantities of furfural and carbon dioxide, and appear to contain a structural unit (11) containing no more than 40% of the carboxyl groups in the oxy-cellulose prepared with alkali hypobromite, the remainder probably represents the structure of the formula (7, U=COOH). This residue may arise from the oxidation of the corresponding dialdehyde, but it can also be obtained from further oxidation of ketones (16) and (17), and therefore the appearance of this residue does not prove that the initial oxidation occurs along a selective periodate pathway. [...]

The second sewerage system consists of separate networks for the removal of toxic and highly mineralized wastewater. This system includes: 1) a network of mineralized wastewater treatment units; 2) sulfur-alkaline wastewater network; 3) a network of acidic wastewater contaminated with mineral acids; 4) a network of acidic wastewater containing fatty acids and paraffin; 5) a network of wastewater from the production of protein-vitamin concentrate (PVC); 6) a network of wastewater containing tetraethyl lead (TES); 7) network for discharging process condensate.[...]

The reaction is carried out like this. To 2-3 cm3 of approximately 0.5% solution of tannins, add 3-5 drops of a 1% solution of ferrous alum (ferrous sulfate is also good). You should not use ferric chloride, which has an acidic reaction in the solution, and the presence of mineral acids in the solution prevents the reaction.[...]

Chemical properties. The presence of a hydroxyl group in S. determines their reactivity. For example, when S. is exposed to alkali metals (potassium, sodium, lithium, etc.), alcoholates are formed - derivatives of S., in which the hydrogen of the hydroxyl group is replaced by a metal. When S. acts on acids, esters are formed. With strong mineral acids, this reaction occurs quickly; the rate of formation of esters with organic acids depends on the structure of the acid and the acid. The removal of water from carbon leads to the formation of either ethylene hydrocarbons or ethers. In the first case, water is released from one S. molecule, in the second - from two. The oxidation of primary carbonates produces aldehydes, and the oxidation of secondary substances produces ketones. The oxidation of tertiary carbons is more difficult and is accompanied by the breaking of bonds between carbon atoms. Unsaturated compounds are characterized by reactions characteristic of unsaturated compounds, while the hydroxyl group gives them all the properties inherent in ordinary saturated compounds. [...]

The amount of calcium and magnesium equivalent to the amount of carbonates and bicarbonates is called carbonate hardness. Non-carbonate hardness is defined as the difference between total and carbonate hardness and shows the amount of alkaline earth metal cations corresponding to the anions of mineral acids: chloride, sulfate, nitrate ions, etc. [...]

Back in 1897, Klason suggested that lignin consists of simple structural units. This alcohol is very sensitive to acids and polymerizes easily.[...]

Anion exchangers are divided into weakly basic, in which the main radical has a dissociation constant less than MO-3, and into strongly basic, in which the main radical has a dissociation constant greater than NO-2. Strong base anion exchangers can absorb any anions, but their regeneration is associated with great difficulties. Weakly basic anion exchange resins exchange the anions of strong acids (BO2-, C1, N0, PO-, etc.), but the anions of weak mineral acids (CO, 5ISO) are practically not absorbed (very slightly in an acidic environment). Therefore, weakly basic anion exchangers are used in the first anionization stage, and strongly basic ones in the second stage.[...]

Hydrocellulose is a mixture of natural cellulose and the initial products of its hydrolysis. The term hydrocellulose was first proposed by Girard in 1875 to designate the powdery residues resulting from the acid hydrolysis of cellulose. Currently, hydrocellulose is defined as “a group of macromolecular substances formed by the hydrolysis of cellulose with acid, any member of this group being hydrocellulose.” Hydrocellulose is obtained under certain conditions of prolonged exposure of cellulose to dilute mineral acids at normal temperatures or during shorter-term treatment with them when heated.[...]

The conditions for cultivating microorganisms significantly affect the production of activated sludge biomass used as a flocculant. If native activated sludge is used as a flocculant, it must be pre-aerated to prevent biomass from rotting and, in addition, to improve flocculating properties. Preliminary acidification or direct supply of a mineral acid solution into the zone of mixing activated sludge with a clarified fine suspension or wastewater intensifies the flocculation process using activated sludge biomass. Reducing the pH to 3 - 4 increases the degree of flocculation of particles of the solid phase of the clarified suspension, leading to virtually the cessation of rotting of the activated sludge biomass and, consequently, the release of explosive gases, such as hydrogen sulfide and methane. This contributes to the safety of work using activated sludge.[...]

Bentonite clays can be active sorbents towards non-ferrous metal ions. At the Kazmekhanobr Institute, the sorption capacity of some clay materials for calcium, cadmium, zinc and copper ions was determined, which amounted to 25-40 mg/dm3 for each ion; Vermiculite capacity reaches 60 mg/dm3. To purify solutions from non-ferrous metal ions at their concentrations of up to 50 mg/dm3, the consumption of natural clay materials is at least 20 g/dm3 of the solution being purified. Treated wastewater mixed with natural clays settles very slowly. There are methods for improving coagulating and sorption properties natural clays, in particular their chemical activation. For example, the action of sulfuric acid on bentonite clay leads to destruction crystal lattice mineral, due to which the treated wastewater is clarified quickly. The main reason for the increase in the sorption capacity of bentonite clays treated with mineral acids and alkalis is the partial dissolution of sesquioxides and metal oxides during activation, which leads to a significant change porous structure clay minerals. To activate natural sorbents, their heat treatment can be used.