Russia and includes chemical and petrochemical industry, subdivided into many industries and industries, as well as the microbiological industry. It provides the production of acids, alkalis, mineral fertilizers, various polymer materials, dyes, household chemicals, varnishes and paints, rubber-asbestos, photochemical and chemical-pharmaceutical products.
Chemical and petrochemical industry features the combination of which makes these industries unique in breadth economic use their products. On the one hand, the products of the complex are used as raw materials and materials in all branches of industry (medical, microbiological, radio engineering, space, woodworking, light), in agriculture and in transport. On the other hand, the process of processing chemical and petrochemical raw materials into the final product includes a large number of technological stages of redistribution, which determines a large share of intra-industry consumption.
The volume of goods shipped by type economic activity“Chemical production” in 2007 accounted for 67% of the output of manufacturing industries. The industry employs 7.6 thousand enterprises, employing more than 500 thousand people.
Since 2000, the volume of investments in fixed assets of the chemical complex at the expense of all sources of financing has increased 6.7 times. Foreign investments during this period exceeded $ 3.7 billion, although the payback period for a large chemical project is 13-26 years.
The current location of the chemical complex has a number of features:
- high concentration of enterprises in the European part of Russia;
- concentration of chemical industry centers in areas that are deficient in water and energy resources, but concentrate the bulk of the population and production potential;
- territorial discrepancy between the regions of production and consumption of the chemical industry;
- the raw material base of the industry, which is differentiated depending on the natural and economic specifics certain regions of the country.
The chemical industry plays the most important role in the economy of the Volga region, the Volga-Vyatka region, the Central Chernozem region, the Urals and the Center. The industry is even more important in the economy of individual regions, where it acts as the basis for the formation of the economy of these territories - in the Novgorod, Tula, Perm regions and Tatarstan.
The products of the Russian chemical complex are used in great demand abroad... In 2007, the volume of exports of chemical and petrochemical products amounted to $ 20.8 billion, or 5.9% of the total exports of the Russian Federation.
The development and location of the chemical complex is due to the influence of a number of factors
Raw material factor has a huge impact on the location of all branches of the chemical complex, and is decisive for the mining and chemical industry and the production of potash fertilizers. In the prime cost of finished products, the share of raw materials for individual industries ranges from 40 to 90%, which is due to either high consumption rates or its value.
Energy factor especially important for the industry of polymeric materials and certain branches of basic chemistry. The chemical complex consumes about 1/5 of the energy resources used in industry. The production of synthetic rubber, phosphorus by electric sublimation and nitrogen fertilizers by the method of water electrolysis, and the soda industry is distinguished by significant fuel consumption.
Water factor plays a special role in the location of chemical enterprises, since water is used for auxiliary purposes and as raw materials. The water consumption in the branches of the chemical complex varies from 50 m3 for the production of chlorine to 6,000 m3 for the production of chemical fibers.
Consumer factor are taken into account when placing, first of all, the branches of basic chemistry - the production of nitrogen and phosphate fertilizers, sulfuric acid, as well as highly specialized enterprises producing varnishes, paints, pharmaceuticals.
Labor factor influences the placement of labor-intensive branches of the chemical complex, which include the production of chemical fibers and plastics.
Environmental factor until recently, it was not sufficiently taken into account when placing enterprises of the chemical complex. However, it is this industry that is one of the main environmental pollutants among the industries (almost 30% of the volume of polluted industrial wastewater). Therefore, the main and decisive for further development and the placement of the industry is transformation traditional technologies in low-waste and resource-saving, the creation of closed technological cycles with the full use of raw materials and not generating waste that goes beyond them.
Infrastructure factor, involving the preparation and arrangement of the territory for industrial development, is especially important when placing industrial enterprises, mainly in areas of new development.
The composition of the chemical complex
As part of the chemical complex, one can distinguish the mining and chemical industry associated with the extraction of primary chemical raw materials, the main chemistry providing the production of mineral fertilizers, sulfuric acid and soda, and the industry of polymer materials (including organic synthesis).
The mining and chemical industry takes the third place in terms of production volume and includes the extraction of apatites, phosphorites, potash and sodium chloride, native sulfur, boron, chalk, etc. salts and phosphate raw materials (apatites and phosphorites), the country ranks first in the world. The main reserves of chemical raw materials are concentrated in the European part of the country. In the Eastern zone, large and profitable deposits have not yet been identified.
In the structure of phosphate raw material reserves, apatite ores prevail, where the main role is played by the Khibiny group in Murmansk region... Almost 90% of the country's proven reserves of potash salts are concentrated in the Verkhnekamskoye field in the Perm Territory, where the production of this raw material is fully carried out in Russia. Table salts are presented on the territory of the Volga region, the Urals, Western and Eastern Siberia, Of the Far East, deposits of sulfur and sulfur pyrite - in the Urals.
Fertilizer production
Basic chemistry takes a leading place in the chemical complex in terms of the volume of products. Her main industry is the mineral fertilizer industry, which includes the production of nitrogen, phosphate and potash fertilizers... In the structure of the production of mineral fertilizers, approximately the same share (more than 2/5) is accounted for by potash and nitrogen fertilizers, and 1/6 - by phosphate fertilizers. In the cost of production of mineral fertilizers, the costs of feedstock, natural gas, electricity and transport account for about 70-80%.
The territorial organization of the production of mineral fertilizers has not undergone any changes over the past decade. As before, more than 95% of the production of mineral fertilizers is concentrated in the Western zone of the country, where the importance of the Urals (2/5 of all-Russian production) has increased even more against the background of the reduction in the role of the Center, North-West, Volga region, Volga-Vyatka region.
Modern nitrogen industry is based on the synthesis and subsequent processing of ammonia, in the cost of which almost 50% of the costs are accounted for by natural gas (as raw materials and fuel). At the same time, the decisive factor in the location is either the presence in the region of gas resources (Nevinnomyssk in the North Caucasus), or consumers of finished products - agriculture - and enterprises are located along the routes of main gas pipelines (Novomoskovsk in Central, Novgorod in North-West, Dzerzhinsk in Volgo-Vyatsky areas). When coke oven gas, which is formed during the coking of coal, is used as a feedstock, nitrogen fertilizer enterprises are built either in coal basins (Kemerovo, Angarsk), or near full-cycle metallurgical plants (Magnitogorsk, Nizhny Tagil, Lipetsk, Cherepovets).
Potash fertilizers are produced at enterprises of the mining and chemical industry, they combine the extraction and processing of potash ores. On the basis of the Verkhnekamskoye deposit, potash fertilizers are produced at two large enterprises in Solikamsk and Berezniki in the Perm Territory.
Production phosphate fertilizers is based on acid processing of phosphate raw materials (phosphorites and apatites) and is carried out at 19 enterprises located in almost all European regions of the country, including the Urals. The decisive factor in the location is the presence of a consumer, therefore, enterprises are built mainly in agricultural areas: Kingisepp (North-West), Voskresensk, Novomoskovsk (Center), Uvarovo (Central Chernozem region), Balakovo (Volga region), Krasnouralsk (Ural).
The sulfuric acid industry produces products that are widely used, especially in the production of phosphate fertilizers. Sulfuric acid production is concentrated in the European part of the country, the main regions are the European North, the Urals and the Center, which provide almost 2/3 of the all-Russian output, slightly less - 1/5 - from the Volga region and the North-West.
A distinctive feature of the soda industry is its attraction to raw material bases - deposits of table salt. Production of caustic and soda ash refers to material-intensive (for the production of 1 ton of finished products, up to 5 m3 of salt brine is consumed), auxiliary materials (about 1.5 tons of limestone per 1 ton of finished products) and fuel and energy resources are widely used. The leading regions where the soda industry is concentrated are the Volga region, the Urals, Eastern Siberia and the Volgo-Vyatka region, which account for over 9/10 of the all-Russian production of caustic and soda ash.
The industry of polymeric materials ranks second in the chemical complex in terms of production volume and includes organic synthesis (production of hydrocarbon raw materials based on oil, gas and coke chemistry), developing on its basis polymer chemistry (production of synthetic rubber, synthetic resins and plastics, chemical fibers ), as well as the processing of polymer products (production of rubber products, tires, plastic products).
The development and distribution of organic synthesis is due to a significant and widespread resource base, which removes territorial restrictions for the industry. Initially, organic synthesis relied on raw materials of wood and agricultural origin, coal, and was presented in Kuzbass, Moscow region, the Urals, as well as in European regions - consumers of finished products. Now the availability of oil and gas raw materials is decisive.
Among the branches of polymer chemistry the largest scale the industry of synthetic resins and plastics stands out, which suffered less than others during the period of market transformations of the economy, the volume of its production decreased by 1/5. The presence of hydrocarbon petrochemical raw materials determines the location of the industry and production is approaching petrochemical plants located in oil production areas or along the routes of oil and gas pipelines.
The expected shifts in the placement of the industry in the Eastern zone did not occur. Over the past 15 years, the share of eastern regions in the all-Russian production of synthetic resins and plastics has decreased from 31 to 26% and the role of the Volga region (Novokuibyshevsk, Volgograd, Volzhsky, Kazan) and the Urals (Ufa, Salavat, Yekaterinburg, Nizhniy Tagil) has increased. . ensured the production of more than 2/5 of the industry's finished products. The situation remains stable in the largest consumption region - Central, where large enterprises operate in Moscow, Ryazan, Yaroslavl.
Chemical fiber industry and yarns in terms of the volume of polymer chemistry products produced, it ranks second and includes the production of artificial (from cellulose) and synthetic fibers (from refined products).
The industry of chemical fibers and threads is characterized by high rates of consumption of raw materials, water, fuel and energy and is oriented towards the regions of the textile industry - Central (Tver, Shuya, Klin, Serpukhov), Povolzhsky (Balakovo, Saratov, Engels). In the east, large enterprises operate in Krasnoyarsk, Barnaul, Kemerovo.
The synthetic rubber industry occupies a special place, since the world's first enterprises based on food raw materials were built in the early 1930s of the twentieth century. in Central Russia. The transition to hydrocarbon feedstock led to the construction of new plants in the Volga region, the Urals, and Western Siberia.
In addition to the high material consumption, the industry is distinguished by a significant electrical intensity (almost 3 thousand kW / h per 1 ton of synthetic rubber) and is characterized by a certain territorial dispersion. Almost 2/3 of the production of synthetic rubber falls on European part, where the Volga region remains the leading region (Kazan, Togliatti, Nizhnekamsk). Significant production volumes are in the Central (Moscow, Yaroslavl), Central Chernozem (Voronezh) and Ural (Ufa, Sterlitamak, Perm) regions. In the east, Omsk ( Western Siberia) and Krasnoyarsk (Eastern Siberia).
Taking into account the resource availability of individual territories and the possibilities of the processing industry, the following are distinguished by large complexes of the chemical industry economic regions Russia:- The center dominated by polymer chemistry (production of synthetic rubber, plastics, chemical fibers), is the production of nitrogen and phosphorus fertilizers, sulfuric acid, dyes and varnishes;
- The Urals, where all types of mineral fertilizers, soda, sulfuric acid, as well as synthetic alcohol, synthetic rubber, plastics from oil and associated gases are produced;
- North-West supplies the all-Russian market with phosphoric fertilizers, sulfuric acid, polymer chemistry products (synthetic resins, plastics, chemical fibers);
- The Volga region provides for the production of various polymer products based on organic synthesis (synthetic rubber, chemical fibers);
- The North Caucasus develops the production of nitrogen fertilizers, organic synthesis, synthetic resins and plastics;
- Siberia (Western and Eastern) is characterized by the development of organic synthesis chemistry and polymer chemistry, and the production of nitrogen fertilizers.
Chemical industry- one of the most important sectors of the world economy, thanks to which full-fledged work of ferrous and non-ferrous metallurgy, construction, agriculture, pharmaceuticals is ensured, Food Industry... V modern world the importance of the chemical industry is very great, since its achievements make life much easier for people.
general characteristics
The chemical industry is based on the processing of raw materials by chemical methods. The basic materials used in this industry are oil and various mineral raw materials. Thanks to her, people have the opportunity to use plastic and plastic products, fertilizers for agriculture, medications, household chemicals and cosmetics, and much more.
Rice. 1. Household chemicals.
Many industries are in need of chemical products, thanks to which the industry is actively developing. The chemical industry is of particular importance for agriculture, automotive industry and construction.
The beginning of the development of the chemical industry is considered to be the beginning of the 17th century, when an industrial revolution took place. Before that, chemistry - the "science of substances" - developed extremely slowly, and only when people learned to apply their knowledge in practice, everything changed. The very first product of the chemical industry was sulfuric acid, which still remains the most important component in the chemical industry.
Rice. 2. Sulfuric acid.
This industry is characterized by the following features:
- Usage a large number raw materials for the manufacture of products. This is especially true for rubber, plastics, soda, fertilizers.
- Chemical industry materials are very diverse.
- High level of energy costs.
- Low labor intensity combined with the need for highly qualified specialists.
- Large investment. The work of chemical enterprises is impossible without complex structures and mechanisms.
- Complex industry structure.
- Environmental problems associated with the manufacture of chemical products.
Branches of the chemical industry
The global chemical industry includes many different areas. Currently, there are more than two hundred different subsectors and industries, and the range of its products reaches one million species.
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The main branches of the chemical industry are:
- Mining chemical - mining, processing and enrichment of sulfur, phosphorites and various salts.
- Basic - production of inorganic substances (fertilizers, acids, soda).
- Industry of polymeric materials - based on organic synthesis and includes production and processing of various polymers (plastic, resin, rubber).
In the era of the scientific and technological revolution, the production of polymer materials was most developed in the chemical industry. Semi-finished petrochemicals are used as raw materials for these products. Polymers are an essential part of industry and construction.
Rice. 3. Plastics production.
Preservation of ecology
The active development of the chemical industry has led to the construction of a large number of industries in large and medium-sized settlements worldwide.
At the same time, only a small number of enterprises are equipped with low-waste or completely waste-free technologies and modern treatment facilities. All this led to the emergence of a difficult ecological situation, especially in developing countries where little attention is paid to environmental protection.
To improve the environmental situation in technological processes the chemical industry needs to implement in a timely manner the following techniques :
- reduction and oxidation using oxygen and nitrogen;
- membrane technology, due to which there is a separation of gas mixtures and from liquid;
- biotechnology;
- electrochemical methods.
What have we learned?
When we studied the topic "Chemical industry", we learned how the chemical industry has a great influence on the development of many important industries. We found out what the main features are inherent in it, what industries it consists of.
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Recently, my friends and I watched a rather interesting film. It told about our future, about what will happen to people's lives. In general, as I understood the genre of this film, it was a fantasy. And in one of the scenes it was said about the growth of the chemical industry, and about the fact that soon we will not be able to fully live, due to the fact that the whole world will be enveloped chemical materials. Everyone, of course, laughed and let this moment pass in passing, but I wondered that indeed chemical industry is gradually moving to the fore, displacing other areas of activity, and this alarmed me a little. I decided to figure it out and now I want to tell you too.
What is the chemical industry
Chemical industry- exceptional activity in economics based on chemicalization process, i.e. use of chemical methods, materials and processes in various sectors of the economy.
It stands out as a complex organization that includes these industries:
- booty mining and chemical raw materials;
- basic chemistry;
- polymer chemistry(organic synthesis).
Even by explaining this term, I have already concluded about the importance of this industry, and this importance is infinitely enormous. After all, the chemical industry includes the possibility of consuming raw materials and recycling almost all production waste, even the most toxic. In my opinion, this is a very powerful argument about the role of this activity in the industrial world. No other industry can compare with chemistry. industry in the production of virtually new materials with predetermined properties.
Factors in the location of chemical industry enterprises
Mainly to placement factors refers to:
- raw factor;
- consumer factor;
- consumer-raw material factor.
The specificity of the location of these industries in Russia is their concentration in the European part of the country. There are several reasons for this feature. Among the main ones are the proximity of the consumer and the availability of raw materials ( consumer-raw material factor).
Placement examples
Basically, of course, the extraction of raw materials can be attributed to raw factor. For example, mining and chemical enterprises are located in Berezniki and Solikamsk, because one of the largest deposits of potash salts is located here. Phosphate fertilizers are produced from apatites mined in the Khibiny. important factor chemical enterprises is consumer factor... Almost all centers are located in large cities... For example, it is more convenient to build an enterprise in St. Petersburg, where many people live and there is demand, than in a provincial town with a small population.
Inorganic substances are simple and complex. Simple substances are divided into metals (K, Na, Li) and non-metals (O, Cl, P). Complex substances are divided into oxides, hydroxides (bases), salts and acids.
Oxides
Oxides- compounds of a chemical element (metal or non-metal) with oxygen (oxidation state -2), while oxygen is associated with a less electronegative element.
Allocate:
1. Acid oxides- oxides showing acidic properties. Formed by non-metals and oxygen. Examples: SO3, SO2, CO2, P2O5, N2O5.
2. Amphoteric oxides- oxides that can exhibit both basic and acidic properties (this property is called amphotericity). Examples: Al2O3, CrO3, ZnO, BeO, PbO.
3. Basic oxides- metal oxides, while the metals exhibit an oxidation state of +1 or +2. Examples: K2O, MgO, CaO, BaO, Li2O, Na2O.
4. Non-salt-forming oxides- practically do not enter into reactions, do not have corresponding acids and hydroxides. Examples: CO, NO.
Chemical properties of basic oxides
1. Interaction with water
Only oxides of alkali and alkaline earth metals enter into the reaction, the hydroxides of which form a soluble base
basic oxide + water → alkali
K2O + H2O → 2KOH
CaO + H2O → Ca (OH) 2
2. Interaction with acid
basic oxide + acid → salt + water
MgO + H2SO4 → MgSO4 + H2O
Na2O + H2S (g) → 2NaHS + H2O
MgO (g) + HCl → Mg (OH) Cl
3. Interaction with acidic or amphoteric oxides
basic oxide + acidic / amphoteric oxide → salt
In this case, the metal in the basic oxide becomes a cation, and the acidic / amphoteric oxide becomes an anion (acidic residue). Reactions between solid oxides occur when heated. Water-insoluble basic oxides do not interact with gaseous acidic oxides.
BaO + SiO2 (t) → BaSiO3
K2O + ZnO (t) → K2ZnO2
FeO + CO2 ≠
4. Interaction with amphoteric hydroxides
basic oxide + amphoteric hydroxide → salt + water
Na2O + 2Al (OH) 3 (t) → 2NaAlO2 + 3H2O
5. Decomposition at a temperature of oxides of noble metals and mercury
2Ag2O (t) → 4Ag + O2
2HgO (t) → 2Hg + O2
6. Interaction with carbon (C) or hydrogen (H2) at high temperatures.
When the oxides of alkali, alkaline earth metals and aluminum are reduced in this way, not the metal itself is released, but its carbide.
FeO + C (t) → Fe + CO
3Fe2O3 + C (t) → 2Fe3O4 + CO
CaO + 3C (t) → CaC2 + CO
CaO + 2H2 (t) → CaH2 + H2O
7. Active metals reduce less active metals from their oxides at high temperatures
CuO + Zn (t) → ZnO + Cu
8. Oxygen oxidizes lower oxides to higher ones.
Alkali and alkaline earth metal oxides are converted to peroxides
4FeO + O2 (t) → 2Fe2O3
2BaO + O2 (t) → 2BaO2
2NaO + O2 (t) → 2Na2O2
Chemical properties of acidic oxides
1. Interaction with water
acid oxide + water → acid
SO3 + H2O → H2SO4
SiO2 + H2O ≠
Some oxides do not have corresponding acids, in which case a disproportionation reaction occurs
2NO2 + H2O → HNO3 + HNO2
3NO2 + H2O (t) → 2HNO3 + NO
2ClO2 + H2O → HClO3 + HClO2
6ClO2 + 3H2O (t) → 5HClO3 + HCl
Depending on the number of water molecules attached to P2O5, three different acids are formed - metaphosphoric НРО3, pyrophosphoric Н4Р2О7 or orthophosphoric Н3РО4.
P2O5 + H2O → 2HPO3
P2O5 + 2H2O → H4P2O7
P2O5 + 3H2O → 2H3PO4
Chromium oxide corresponds to two acids - chromic H2CrO4 and dichromic H2Cr2O7 (III)
CrO3 + H2O → H2CrO4
2CrO3 + H2O → H2Cr2O7
2. Interaction with bases
acid oxide + base → salt + water
Insoluble acidic oxides react only upon fusion, and soluble ones under normal conditions.
SiO2 + 2NaOH (t) → Na2SiO3 + H2O
With an excess of oxide, an acidic salt is formed.
CO2 (g) + NaOH → NaHCO3
P2O5 (g) + 2Ca (OH) 2 → 2CaHPO4 + H2O
P2O5 (g) + Ca (OH) 2 + H2O → Ca (H2PO4) 2
With an excess of base, a basic salt is formed
CO2 + 2Mg (OH) 2 (g) → (MgOH) 2CO3 + H2O
Oxides that do not have corresponding acids undergo disproportionation reactions and form two salts.
2NO2 + 2NaOH → NaNO3 + NaNO2 + H2O
2ClO2 + 2NaOH → NaClO3 + NaClO2 + H2O
CO2 reacts with some amphoteric hydroxides (Be (OH) 2, Zn (OH) 2, Pb (OH) 2, Cu (OH) 2) to form basic salt and water.
CO2 + 2Be (OH) 2 → (BeOH) 2CO3 ↓ + H2O
CO2 + 2Cu (OH) 2 → (CuOH) 2CO3 ↓ + H2O
3. Interaction with basic or amphoteric oxide
acidic oxide + basic / amphoteric oxide → salt
Reactions between solid oxides take place during fusion. Amphoteric and water-insoluble basic oxides interact only with solid and liquid acidic oxides.
SiO2 + BaO (t) → BaSiO3
3SO3 + Al2O3 (t) → Al2 (SO4) 3
4. Interaction with salt
acidic non-volatile oxide + salt (t) → salt + acidic volatile oxide
SiO2 + CaCO3 (t) → CaSiO3 + CO2
P2O5 + Na2CO3 → 2Na3PO4 + 2CO2
5. Acidic oxides do not interact with acids, but P2O5 reacts with anhydrous oxygen-containing acids.
In this case, HPO3 and the corresponding acid anhydride are formed
P2O5 + 2HClO4 (anhydrous) → Cl2O7 + 2HPO3
P2O5 + 2HNO3 (anhydrous) → N2O5 + 2HPO3
6. Enter into redox reactions.
1. Recovery
At high temperatures, some non-metals can reduce oxides.
CO2 + C (t) → 2CO
SO3 + C → SO2 + CO
H2O + C (t) → H2 + CO
Magnesium thermal is often used to reduce non-metals from their oxides.
CO2 + 2Mg → C + 2MgO
SiO2 + 2Mg (t) → Si + 2MgO
N2O + Mg (t) → N2 + MgO
2. Lower oxides are converted into higher ones when interacting with ozone (or oxygen) at high temperatures in the presence of a catalyst
NO + O3 → NO2 + O2
SO2 + O3 → SO3 + O2
2NO2 + O3 → N2O5 + O2
2CO + O2 (t) → 2CO2
2SO2 + O2 (t, kat) → 2SO3
P2O3 + O2 (t) → P2O5
2NO + O2 (t) → 2NO2
2N2O3 + O2 (t) → 2N2O4
3. Oxides also enter into other redox reactions
SO2 + NO2 → NO + SO3 4NO2 + O2 + 2H2O → 4HNO3
2SO2 + 2NO → N2 + 2SO3 2N2O5 → 4NO2 + O2
SO2 + 2H2S → 3S ↓ + 2H2O 2NO2 (t) → 2NO + O2
2SO2 + O2 + 2H2O → 2H2SO4 3N2O + 2NH3 → 4N2 + 3H2O
2CO2 + 2Na2O2 → 2Na2CO3 + O2 10NO2 + 8P → 5N2 + 4P2O5
N2O + 2Cu (t) → N2 + Cu2O
2NO + 4Cu (t) → N2 + 2Cu2O
N2O3 + 3Cu (t) → N2 + 3CuO
2NO2 + 4Cu (t) → N2 + 4CuO
N2O5 + 5Cu (t) → N2 + 5CuO
Chemical properties of amphoteric oxides
1. Do not interact with water
amphoteric oxide + water ≠
2. Interaction with acids
amphoteric oxide + acid → salt + water
Al2O3 + 3H2SO4 → Al2 (SO4) 3 + 3H2O
With an excess of polybasic acid, an acid salt is formed
Al2O3 + 6H3PO4 (g) → 2Al (H2PO4) 3 + 3H2O
With an excess of oxide, a basic salt is formed
ZnO (g) + HCl → Zn (OH) Cl
Double oxides form two salts
Fe3O4 + 8HCl → FeCl2 + 2FeCl3 + 4H2O
3. Interaction with acidic oxide
amphoteric oxide + acidic oxide → salt
Al2O3 + 3SO3 → Al2 (SO4) 3
4. Interaction with alkali
amphoteric oxide + alkali → salt + water
During fusion, medium salt and water are formed, and in solution - complex salt
ZnO + 2NaOH (tv) (t) → Na2ZnO2 + H2O
ZnO + 2NaOH + H2O → Na2
5. Interaction with basic oxide
amphoteric oxide + basic oxide (t) → salt
ZnO + K2O (t) → K2ZnO2
6. Interaction with salts
amphoteric oxide + salt (t) → salt + volatile acidic oxide
Amphoteric oxides displace volatile acid oxides from their salts during fusion
Al2O3 + K2CO3 (t) → KAlO2 + CO2
Fe2O3 + Na2CO3 (t) → 2NaFeO2 + CO2
Chemical properties of bases
Bases are substances that include a metal cation and a hydroxide anion. Bases are soluble (alkalis - NaOH, KOH, Ba (OH) 2) and insoluble (Al2O3, Mg (OH) 2).
1. Soluble base + indicator → color change
When the indicator is added to the base solution, its color changes:
Colorless phenolphthalein - raspberry
Purple litmus - blue
Methyl orange - yellow
2. Interaction with acid (neutralization reaction)
base + acid → salt + water
By the reaction, medium, acidic or basic salts can be obtained. With an excess of a polyacidic acid, an acidic salt is formed, with an excess of a polyacidic base, a basic salt is formed.
Mg (OH) 2 + H2SO4 → MGSO4 + 2H2O
Mg (OH) 2 + 2H2SO4 → MG (HSO4) 2 + 2H2O
2Mg (OH) 2 + H2SO4 → (MgOH) 2SO4 + 2H2O
3. Interaction with acidic oxides
base + acid oxide → salt + water
6NH4OH + P2O5 → 2 (NH4) 3PO4 + 3H2O
4. Interaction of alkali with amphoteric hydroxide
alkali + amphoteric hydroxide → salt + water
In this reaction, amphoteric hydroxide exhibits acidic properties. During the reaction in the melt, average salt and water are obtained, and in the solution, a complex salt is obtained. Iron (III) and chromium (III) hydroxides dissolve only in concentrated alkali solutions.
2KOH (tv) + Zn (OH) 2 (t) → K2ZnO2 + 2H2O
KOH + Al (OH) 3 → K
3NaOH (conc) + Fe (OH) 3 → Na3
5. Interaction with amphoteric oxide
alkali + amphoteric oxide → salt + water
2NaOH (s) + Al2O3 (t) → 2NaAlO2 + H2O
6NaOH + Al2O3 + 3H2O → 2Na3
6. Interaction with salt
An ion exchange reaction occurs between the base and the salt. It occurs only during the precipitation of a precipitate or during the evolution of gas (with the formation of NH4OH).
A. Reaction between soluble base and soluble acid salt
soluble base + soluble acid salt → medium salt + water
If the salt and base are formed by different cations, then two middle salts are formed. In the case of acidic ammonium salts, excess alkali leads to the formation of ammonium hydroxide.
Ba (OH) 2 + Ba (HCO3) 2 → 2BaCO3 ↓ + 2H2O
2NaOH (g) + NH4HS → Na2S + NH4OH + H2O
B. Reaction of a soluble base with a soluble medium or basic salt.
Several scenarios are possible
soluble base + soluble medium / basic salt → insoluble salt ↓ + base
→ salt + insoluble base ↓
→ salt + weak electrolyte NH4OH
→ there is no reaction
Reactions occur between soluble bases and a medium salt only if the result is an insoluble salt, or an insoluble base, or a weak electrolyte NH4OH
NaOH + KCl ≠ the reaction does not go
If the original salt is formed by a multi-acid base, with a lack of alkali, a basic salt is formed
Under the action of alkalis on silver and mercury (II) salts, not their hydroxides are released, which dissolve at 25C, but insoluble oxides Ag2O and HgO.
7. Decomposition at temperature
basic hydroxide (t) → oxide + water
Ca (OH) 2 (t) → CaO + H2O
NaOH (t) ≠
Some bases (AgOH, Hg (OH) 2 and NH4OH) decompose even at room temperature
LiOH (t) → Li2O + H2O
NH4OH (25C) → NH3 + H2O
8. Interaction of alkali and transition metal
alkali + transition metal → salt + H2
2Al + 2KOH + 6H2O → 2K + 3H2
Zn + 2NaOH (s) (t) → Na2ZnO2 + H2
Zn + 2NaOH + 2H2O → Na2 + H2
9. Interaction with non-metals
Alkalis interact with some non-metals - Si, S, P, F2, Cl2, Br2, I2. In this case, two salts are often formed as a result of disproportionation.
Si + 2KOH + H2O → K2SiO3 + 2H2
3S + 6KOH (t) → 2K2S + K2SO3 + 3H2O
Cl2 + 2KOH (conc) → KCl + KClO + H2O (for Br, I)
3Cl2 + 6KOH (conc) (t) → 5KCl + KClO3 + 3H2O (for Br, I)
Cl2 + Ca (OH) 2 → CaOCl2 + H2O
4F2 + 6NaOH (decomp) → 6NaF + OF2 + O2 + 3H2O
4P + 3NaOH + 3H2O → 3NaH2PO2 + PH3
Hydroxides with reducing properties can be oxidized by oxygen
4Fe (OH) 2 + O2 + 2H2O → 4Fe (OH) 3 (= Cr)
Chemical properties of acids
1. Change the color of the indicator
soluble acid + indicator → color change
Violet litmus and methyl orange turn red, phenolphthalein becomes transparent
2. Interaction with bases (neutralization reaction)
acid + base → salt + water
H2SO4 + Mg (OH) 2 → MgSO4 + 2H2O
3. Interaction with basic oxide
acid + basic oxide → salt + water
2HCl + CuO → CuCl2 + H2O
4. Interaction with amphoteric hydroxides with the formation of medium, acidic or basic salts
acid + amphoteric hydroxide → salt + water
2HCl + Be (OH) 2 → BeCl2 + 2H2O
H3PO4 () + Zn (OH) 2 → ZNHPO4 + 2H2O
HCl + Al (OH) 3 () → Al (OH) 2Cl + H2O
5. Interaction with amphoteric oxides
acid + amphoteric oxide → salt + water
H2SO4 + ZnO → ZnSO4 + H2O
6. Interaction with salts
General reaction scheme: acid + salt → salt + acid
An ion exchange reaction takes place, which goes to the end only in the case of gas formation or precipitation.
For example: HCl + AgNO3 → AgCl ↓ + HNO3
2HBr + K2SiO3 → 2KBr + H2SiO3 ↓
A. Reaction with a salt of a more volatile or weaker acid to form a gas
HCl + NaHS → NaCl + H2S
B. Reaction between a strong acid and a strong or moderate acid salt to form an insoluble salt
strong acid + strong / medium acid salt → insoluble salt + acid
Non-volatile phosphoric acid displaces strong, but volatile hydrochloric and nitric acids from their salts, subject to the formation of an insoluble salt
B. Interaction of an acid with a basic salt of the same acid
acid1 + basic acid salt1 → medium salt + water
HCl + Mg (OH) Cl → MgCl2 + H2O
D. The interaction of a polybasic acid with a medium or acidic salt of the same acid with the formation of an acidic salt of the same acid containing a greater number of hydrogen atoms
polybasic acid1 + medium / acidic acid salt1 → acidic acid1
H3PO4 + Ca3 (PO4) 2 → 3CaHPO4
H3PO4 + CaHPO4 → Ca (H2PO4) 2
E. Interaction of hydrogen sulfide acid with salts of Ag, Cu, Pb, Cd, Hg with the formation of insoluble sulfide
acid H2S + salt Ag, Cu, Pb, Cd, Hg → Ag2S / CuS / PbS / CdS / HgS ↓ + acid
H2S + CuSO4 → CuS ↓ + H2SO4
E. Reaction of an acid with a medium or complex salt with an amphoteric metal in the anion
a) in the case of a lack of acid, a medium salt and amphoteric hydroxide are formed
acid + medium / complex salt in amphoteric metal in anion → medium salt + amphoteric hydroxide
b) in the case of an excess of acid, two average salts and water are formed
acid + medium / complex salt with amphoteric metal in the anion → medium salt + medium salt + water
G. In some cases, acids with salts enter into redox reactions or complexation reactions:
H2SO4 (conc) and I‾ / Br‾ (products H2S and I2 / SO2 and Br2)
H2SO4 (conc) and Fe² + (products SO2 and Fe³ +)
HNO3 diluted / conc and Fe² + (products NO / NO2 and Fe³ +)
HNO3 open / conc and SO3²‾ / S²‾ (products NO / NO2 and SO4²‾ / S or SO4²‾)
HClconc and KMnO4 / K2Cr2O7 / KClO3 (products Cl2 and Mn² + / Cr² + / Cl‾)
3. Interaction of concentrated sulfuric acid with solid salt
Non-volatile acids can displace volatile acids from their solid salts
7. Interaction of acid with metal
A. Interaction of acid with metals in a row before or after hydrogen
acid + metal up to Н2 → silt metal in the minimum oxidation state + Н2
Fe + H2SO4 (diluted) → FeSO4 + H2
acid + metal after H2 ≠ the reaction does not go
Cu + H2SO4 (decomp) ≠
B. Interaction of concentrated sulfuric acid with metals
H2SO4 (conc) + Au, Pt, Ir, Rh, Ta ≠ the reaction is not proceeding
H2SO4 (conc) + alkali / alkaline earth metal and Mg / Zn → H2S / S / SO2 (depending on conditions) + metal sulfate in the maximum oxidation state + H2O
Zn + 2H2SO4 (conc) (t1) → ZnSO4 + SO2 + 2H2O
3Zn + 4H2SO4 (end) (t2> t1) → 3ZnSO4 + S ↓ + 4H2O
4Zn + 5H2SO4 (end) (t3> t2) → 4ZnSO4 + H2S + 4H2O
H2SO4 (conc) + other metals → SO2 + metal sulfate in the maximum oxidation state + H2O
Cu + 2H2SO4 (conc) (t) → CuSO4 + SO2 + 2H2O
2Al + 6H2SO4 (conc) (t) → Al2 (SO4) 3 + 3SO2 + 6H2O
B. Reaction of concentrated nitric acid with metals
HNO3 (conc) + Au, Pt, Ir, Rh, Ta, Os ≠ the reaction does not proceed
HNO3 (conc) + Pt ≠
HNO3 (conc) + alkali / alkaline earth metal → N2O + metal nitrate in the maximum oxidation state + H2O
4Ba + 10HNO3 (conc) → 4Ba (NO3) 2 + N2O + 5H2O
HNO3 (conc) + other metals at temperature → NO2 + metal nitrate in the maximum oxidation state + H2O
Ag + 2HNO3 (conc) → AgNO3 + NO2 + H2O
It interacts with Fe, Co, Ni, Cr and Al only when heated, since under normal conditions these metals are passivated with nitric acid - they become chemically resistant
D. Reaction of dilute nitric acid with metals
HNO3 (decomposition) + Au, Pt, Ir, Rh, Ta ≠ the reaction does not proceed
Very passive metals (Au, Pt) can be dissolved in aqua regia - a mixture of one volume of concentrated nitric acid with three volumes of concentrated hydrochloric acid. The oxidizing agent in it is atomic chlorine, which is split off from nitrosyl chloride, which is formed as a result of the reaction: HNO3 + 3HCl → 2H2O + NOCl + Cl2
HNO3 (decomp) + alkaline / alkaline earth metal → NH3 (NH4NO3) + metal nitrate in maximum oxidation state + H2O
NH3 is converted to NH4NO3 in excess of nitric acid
4Ca + 10HNO3 (diluted) → 4Ca (NO3) 2 + NH4NO3 + 3H2O
HNO3 (broken) + metal in the series of stresses up to Н2 → NO / N2O / N2 / NH3 (depending on conditions) + metal nitrate in the maximum oxidation state + Н2О
With the rest of the metals, which are in the series of voltages up to hydrogen and non-metals, HNO3 (diluted) forms salt, water and, mainly, NO, but, depending on the conditions, both N2O, and N2, and NH3 / NH4NO3 (the more diluted the acid , the lower the oxidation state of nitrogen in the emitted gaseous product)
3Zn + 8HNO3 (decomp) → 3Zn (NO3) 2 + 2NO + 4H2O
4Zn + 10HNO3 (decomp) → 4Zn (NO3) 2 + N2O + 5H2O
5Zn + 12HNO3 (decomp) → 5Zn (NO3) 2 + N2 + 6H2O
4Zn + 10HNO3 (fine parsed) → 4Zn (NO3) 2 + NH4NO3 + 3H2O
HNO3 (decomp) + metal after Н2 → NO + metal nitrate in the maximum oxidation state + H2O
With low-activity metals, standing after H2, HNO3 dissociates forms salt, water and NO
3Cu + 8HNO3 (decomp) → 3Cu (NO3) 2 + 2NO + 4H2O
8. Decomposition of acids at temperature
acid (t) → oxide + water
H2CO3 (t) → CO2 + H2O
H2SO3 (t) → SO2 + H2O
H2SiO3 (t) → SiO2 + H2O
2H3PO4 (t) → H4P2O7 + H2O
H4P2O7 (t) → 2HPO3 + H2O
4HNO3 (t) → 4NO2 + O2 + 2H2O
3HNO2 (t) → HNO3 + 2NO + H2O
2HNO2 (t) → NO2 + NO + H2O
3HCl (t) → 2HCl + HClO3
4H3PO3 (t) → 3H3PO4 + PH3
9. Interaction of acid with non-metals (redox reaction). In this case, the non-metal is oxidized to the corresponding acid, and the acid is reduced to a gaseous oxide: H2SO4 (conc) - to SO2; HNO3 (conc) - up to NO2; HNO3 (diluted) - to NO.
S + 2HNO3 (decomp) → H2SO4 + 2NO
S + 6HNO3 (conc) → H2SO4 + 6NO2 + 2H2O
S + 2H2SO4 (conc) → 3SO2 + CO2 + 2H2O
C + 2H2SO4 (conc) → 2SO2 + CO2 + 2H2O
C + 4HNO3 (conc) → 4NO2 + CO2 + 2H2O
P + 5HNO3 (decomp) + 2H2O → 3H3PO4 + 5NO
P + 5HNO3 (conc) → HPO3 + 5NO2 + 2H2O
H2S + G2 → 2HG + S ↓ (except F2)
H2SO3 + G2 + H2O → 2HG + H2SO4 (except F2)
2H2S (aq) + O2 → 2H2O + 2S ↓
2H2S + 3O2 → 2H2O + 2SO2 (combustion)
2H2S + O2 (short) → 2H2O + 2S ↓
More active halogens displace less active ones from NG acids (exception: F2 reacts with water, not acid)
2HBr + Cl2 → 2HCl + Br2 ↓
2HI + Cl2 → 2HCl + I2 ↓
2HI + Br2 → 2HBr + I2 ↓
10. Redox reactions between acids
H2SO4 (conc) 2HBr → Br2 ↓ + SO2 + 2H2O
H2SO4 (conc) + 8HI → 4I2 ↓ + H2S + 4H2O
H2SO4 (conc) + HCl ≠
H2SO4 (conc) + H2S → S ↓ + SO2 + 2H2O
3H2SO4 (conc) + H2S → 4SO2 + 4H2O
H2SO3 + 2H2S → 3S ↓ + 3H2O
2HNO3 (conc) + H2S → S ↓ + 2NO2 + 2H2O
2HNO3 (conc) + SO2 → H2SO4 + 2NO2
6HNO3 (conc) + HI → HIO3 + 6NO2 + 3H2O
2HNO3 (conc) + 6HCl → 3Cl2 + 2NO + 4H2O
Chemical properties of amphoteric hydroxides
1. Interaction with basic oxide
amphoteric hydroxide + basic oxide → salt + water
2Al (OH) 3 + Na2O (t) → 2NaAlO2 + 3H2O
2. Interaction with amphoteric or acidic oxide
amphoteric hydroxide + amphoteric / acidic oxide ≠ no reaction
Some amphoteric oxides (Be (OH) 2, Zn (OH) 2, Pb (OH) 2) react with acidic oxide CO2 to form precipitates of basic salts and water
2Be (OH) 2 + CO2 → (BeOH) 2CO3 ↓ + H2O
3. Interaction with alkali
amphoteric hydroxide + alkali → salt + water
Zn (OH) 2 + 2KOH (tv) (t) → K2ZnO2 + 2H2O
Zn (OH) 2 + 2KOH → K2
4. Does not interact with insoluble bases or amphoteric hydroxides
amphoteric hydroxide + insoluble base / amphoteric hydroxide ≠ no reaction
5. Interaction with acids
amphoteric hydroxide + acid → salt + water
Al (OH) 3 + 3HCl → AlCl3 + 3H2O
6. Do not react with salts
amphoteric hydroxide + salt ≠ no reaction
7. Do not react with metals / non-metals (simple substances)
amphoteric hydroxide + metal / non-metal ≠ no reaction
8. Thermal decomposition
amphoteric hydroxide (t) → amphoteric oxide + water
2Al (OH) 3 (t) → Al2O3 + 3H2O
Zn (OH) 2 (t) → ZnO + H2O
General information about salts
Let's imagine that we have an acid and an alkali, we carry out a neutralization reaction between them and get an acid and a salt.
NaOH + HCl → NaCl (sodium chloride) + H2O
It turns out that the salt consists of a metal cation and an acid residue anion.
Salts are:
1. Acidic (with one or two hydrogen cations (that is, they have an acidic (or slightly acidic) environment) - KHCO3, NaHSO3).
2. Medium (I have a metal cation and an acid residue anion, the medium must be determined using a pH meter - BaSO4, AgNO3).
3. Basic (have a hydroxide ion, that is, an alkaline (or weakly alkaline) medium - Cu (OH) Cl, Ca (OH) Br).
There are also double salts that form cations of two metals (K) upon dissociation.
Salts, with a few exceptions, are crystalline solids with high melting points. Most salts white(KNO3, NaCl, BaSO4, etc.). Some salts are colored (K2Cr2O7 - orange, K2CrO4 - yellow, NiSO4 - green, CoCl3 - pink, CuS - black). According to their solubility, they can be divided into soluble, slightly soluble and practically insoluble. Acidic salts are generally better soluble in water than the corresponding average, and basic ones are worse.
Chemical properties of salts
1. Salt + water
When many salts are dissolved in water, their partial or complete decomposition occurs - hydrolysis... Some salts form crystalline hydrates. When medium salts containing an amphoteric metal in the anion are dissolved in water, complex salts are formed.
NaCl + H2O → NaOH + HCl
Na2ZnO2 + 2H2O = Na2
2. Salt + Basic oxide ≠ the reaction does not go
3. Salt + amphoteric oxide → (t) acid volatile oxide + salt
Amphoteric oxides displace volatile acid oxides from their salts during fusion.
Al2O3 + K2CO3 → KAlO2 + CO2
Fe2O3 + Na2CO3 → 2NaFeO2 + CO2
4. Salt + acidic non-volatile oxide → acidic volatile oxide + salt
Non-volatile acidic oxides displace volatile acidic oxides from their salts upon fusion.
SiO2 + CaCO3 → (t) CaSiO3 + CO2
P2O5 + Na2CO3 → (t) 2Na3PO4 + 3CO2
3SiO2 + Ca3 (PO4) 2 → (t) 3CaSiO3 + P2O5
5. Salt + base → base + salt
Reactions between salts and bases are ion exchange reactions. Therefore, under normal conditions, they proceed only in solutions (and the salt and base must be soluble) and only under the condition that a precipitate or a weak electrolyte (H2O / NH4OH) is formed as a result of exchange; gaseous products are not formed in these reactions.
A. Soluble base + soluble acidic salt → medium salt + water
If the salt and the base are formed by different cations, then two average salts are formed; in the case of acidic ammonium salts, an excess of alkali leads to the formation of ammonium hydroxide.
Ba (OH) 2 + Ba (HCO3) → 2BaCO3 + 2H2O
2KOH + 2NaHCO3 → Na2CO3 + K2CO3 + 2H2O
2NaOH + 2NH4HS → Na2S + (NH4) 2S + 2H2O
2NaOH (g) + NH4Hs → Na2S + NH4OH + H2O
B. Soluble base + soluble medium / basic salt → insoluble salt ↓ + base
Soluble base + soluble medium / basic salt → salt + insoluble base ↓
Soluble base + soluble medium / basic salt → salt + weak electrolyte NH4OH
Soluble base + soluble medium / basic salt → no reaction
The reaction between soluble bases and an average / basic salt occurs only if, as a result of ion exchange, an insoluble salt, or an insoluble base, or a weak electrolyte NH4OH is formed.
Ba (OH) 2 + Na2SO4 → BaSO4 ↓ + 2NaOH
2NH4OH + CuCl2 → 2NH4Cl + Cu (OH) 2 ↓
Ba (OH) 2 + NH4Cl → BaCl2 + NH4OH
NaOH + KCl ≠
If the starting salt is formed by a polyacid base, a base salt is formed when there is a lack of alkali.
NaOH (short) + AlCl3 → Al (OH) Cl2 + NaCl
Under the action of alkalis on silver and mercury (II) salts, not AgOH and Hg (OH) 2 are released, which decompose at room temperature, but insoluble oxides Ag2O and HgO.
2AgNO3 + 2NaOH → Ag2O ↓ 2NaNO3 + H2O
Hg (NO3) 2 + 2KOH → HgO ↓ + 2KNO3 + H2O
6. Salt + amphoteric hydroxide → the reaction does not go
7. Salt + acid → acid + salt
Mostly. the reactions of acids with salts are reactions of ion exchange, therefore they occur in solutions and only if, in this case, an acid-insoluble salt or a weaker and volatile acid is formed.
HCl + AgNO3 → AgCl ↓ + HNO3
2HBr + K2SiO3 → 2KBr + H2SiO3 ↓
2HNO3 + Na2CO3 → 2NaNO3 + H2O + CO2
A. Acid1 + salt of more volatile / weak acid2 → salt of acid1 + more volatile / weak acid2
Acids interact with solutions of salts of weaker or volatile acids. Regardless of the salt composition (medium, acidic, basic), as a rule, a medium salt and a weaker volatile acid are formed.
2CH3COOH + Na2S → 2CH3COONa + H2S
HCl + NaHS → NaCl + H2S
B. Strong acid + strong / medium acid salt → insoluble salt ↓ + acid
Strong acids interact with solutions of salts of other strong acids to form an insoluble salt. Non-volatile Н3РО4 (medium strength acid) displaces strong, but volatile hydrochloric HCl and nitric HNO3 acids from their salts, provided that an insoluble salt is formed.
H2SO4 + Ca (NO3) 2 → CaSO4 ↓ + 2HNO3
2H3PO4 + 3CaCl2 → Ca3 (PO4) 2 ↓ + 6HCl
H3PO4 + 3AgNO3 → Ag3PO4 ↓ + 3HNO3
B. Acid1 + basic acid salt1 → medium salt + water
When an acid acts on a basic salt of the same acid, a medium salt and water are formed.
HCl + Mg (OH) Cl → MgCl2 + H2O
D. Polybasic acid1 + medium / acidic acid salt1 → acidic acid1
When a polybasic acid acts on an average salt of the same acid, an acid salt is formed, and when an acid salt is acted upon, an acid salt is formed containing a greater number of hydrogen atoms.
H3PO4 + Ca3 (PO4) → 3CaHPO4
H3PO4 + CaHPO4 → Ca (H2PO4) 2
CO2 + H2O + CaCO3 → Ca (HCO3) 2
E. Acid H2S + salt Ag, Cu, Pb, Cd, Hg → Ag2S / CuS / PbS / CdS / HgS ↓ + acid
Weak and volatile hydrogen sulfide acid H2S displaces even strong acids from solutions of Ag, Cu, Pb, Cd and Hg salts, forming sulfide precipitates with them, insoluble not only in water, but also in the resulting acid.
H2S + CuSO4 → CuS ↓ + H2SO4
E. Acid + medium / complex salt with amphoteric Me in the anion → medium salt + amphoteric hydroxide ↓
→ medium salt + medium salt + H2O
When an acid acts on a medium or complex salt with an amphoteric metal in the anion, the salt is destroyed and forms:
a) in case of lack of acid - medium salt and amphoteric hydroxide
b) in the case of an excess of acid - two medium salts and water
2HCl (weeks) + Na2ZnO2 → 2NaCl + Zn (OH) 2 ↓
2HCl (week) + Na2 → 2NaCl + Zn (OH) 2 ↓ + 2H2O
4HCl (g) + Na2ZnO2 → 2NaCl + ZnCl2 + 2H2O
4HCl (g) + Na2 → 2NaCl + ZnCl2 + 4H2O
It should be borne in mind that in some cases, ORP or complexation reactions occur between acids and salts. So, the OVR is joined by:
H2SO4 conc. and I‾ / Br‾ (products H2S and I2 / SO2 and Br2)
H2SO4 conc. and Fe² + (products SO2 and Fe³ + )
HNO3 dil. / Conc. and Fe² + (products NO / NO2 and Fe 3 + )
HNO3 dil. / Conc. and SO3²‾ / S²‾ (NO / NO2 products and sulfate / sulfur or sulfate)
HCl conc. and KMnO4 / K2Cr2O7 / KClO3 (products are chlorine (gas) and Mn²+ / Cr³ + / Cl‾.
G. The reaction takes place without solvent.
Sulfuric acid conc. + salt (TV) → acidic / medium salt + acidic
Non-volatile acids can displace volatile acids from their dry salts. Most often, the interaction of concentrated sulfuric acid with dry salts of strong and weak acids is used, with the formation of an acid and an acidic or medium salt.
H2SO4 (conc) + NaCl (tv) → NaHSO4 + HCl
H2SO4 (conc) + 2NaCl (tv) → Na2SO4 + 2HCl
H2SO4 (conc) + KNO3 (tv) → KHSO4 + HNO3
H2SO4 (conc) + CaCO3 (tv) → CaSO4 + CO2 + H2O
8. Soluble salt + soluble salt → insoluble salt ↓ + salt
Reactions between salts are exchange reactions. Therefore, under normal conditions, they proceed only if:
a) both salts are soluble in water and taken in the form of solutions
b) as a result of the reaction, a precipitate or a weak electrolyte is formed (the latter is very rare).
AgNO3 + NaCl → AgCl ↓ + NaNO3
If one of the starting salts is insoluble, the reaction proceeds only when an even more insoluble salt is formed as a result. The criterion for "insolubility" is the PR value (solubility product), however, since its study goes beyond school course, the cases when one of the reagent salts is insoluble are not further considered.
If a salt is formed in the exchange reaction, which completely decomposes as a result of hydrolysis (in the solubility table there are dashes in place of such salts), then the products of the hydrolysis of this salt become the reaction products.
Al2 (SO4) 3 + K2S ≠ Al2S3 ↓ + K2SO4
Al2 (SO4) 3 + K2S + 6H2O → 2Al (OH) 3 ↓ + 3H2S + K2SO4
FeCl3 + 6KCN → K3 + 3KCl
AgI + 2KCN → K + KI
AgBr + 2Na2S2O3 → Na3 + NaBr
Fe2 (SO4) 3 + 2KI → 2FeSO4 + I2 + K2SO4
NaCl + NaHSO4 → (t) Na2SO4 + HCl
Medium salts sometimes interact with each other to form complex salts. OVR is possible between salts. Some salts interact when fusing.
9. Salt of less active metal + metal more active → metal less active ↓ + salt
The more active metal displaces the less active metal (standing to the right in the series of stress) from the solution of its salt, thus forming a new salt, and the less active metal is released in a free form (settles on the plate of the active metal). The exception is that alkali and alkaline earth metals in solution interact with water.
Salts with oxidizing properties in solution enter into other redox reactions with metals.
FeSO4 + Zn → Fe ↓ + ZnSO4
ZnSO4 + Fe ≠
Hg (NO3) 2 + Cu → Hg ↓ + Cu (NO3) 2
2FeCl3 + Fe → 3FeCl2
FeCl3 + Cu → FeCl2 + CuCl2
HgCl2 + Hg → Hg2Cl2
2CrCl3 + Zn → 2CrCl2 + ZnCl2
Metals can displace each other from molten salts (the reaction is carried out without air access). It should be remembered that:
a) when melted, many salts decompose
b) a series of metal stress determines the relative activity of metals only in aqueous solutions (for example, Al in aqueous solutions is less active than alkaline earth metals, and in melts it is more active)
K + AlCl3 (melt) → (t) 3KCl + Al
Mg + BeF2 (melt) → (t) MgF2 + Be
2Al + 3CaCl2 (melt) → (t) 2AlCl3 + 3Ca
10. Salt + non-metal
Reactions of salts with non-metals are few. These are redox reactions.
5KClO3 + 6P → (t) 5KCl + 3P2O5
2KClO3 + 3S → (t) 2KCl + 2SO2
2KClO3 + 3C → (t) 2KCl + 3CO2
More active halogens displace less active halogen salts from solutions. An exception is molecular fluorine, which in solutions reacts not with salt, but with water.
2FeCl2 + Cl2 → (t) 2FeCl3
2NaNO2 + O2 → 2NaNO3
Na2SO3 + S → (t) Na2S2O3
BaSO4 + 2C → (t) BaS + 2CO2
2KClO3 + Br2 → (t) 2KBrO3 + Cl2 (the same reaction is typical for iodine)
2KI + Br2 → 2KBr + I2 ↓
2KBr + Cl2 → 2KCl + Br2 ↓
2NaI + Cl2 → 2NaCl + I2 ↓
11. Decomposition of salts.
Salt → (t) thermal decomposition products
1. Salts of nitric acid
The products of thermal decomposition of nitrates depend on the position of the metal cation in the series of metal stresses.
MeNO3 → (t) (for Me to the left of Mg (excluding Li)) MeNO2 + O2
MeNO3 → (t) (for Me from Mg to Cu, as well as Li) MeO + NO2 + O2
MeNO3 → (t) (for Me to the right of Cu) Me + NO2 + O2
(during the thermal decomposition of iron (II) / chromium (II) nitrate, iron (III) / chromium (III) oxide is formed.
2. Ammonium salts
All ammonium salts decompose on ignition. Most often, this produces ammonia NH3 and acid or its decomposition products.
NH4Cl → (t) NH3 + HCl (= NH4Br, NH4I, (NH4) 2S)
(NH4) 3PO4 → (t) 3NH3 + H3PO4
(NH4) 2HPO4 → (t) 2NH3 + H3PO4
NH4H2PO4 → (t) NH3 + H3PO4
(NH4) 2CO3 → (t) 2NH3 + CO2 + H2O
NH4HCO3 → (t) NH3 + CO2 + H2O
Sometimes ammonium salts containing oxidizing anions decompose on heating with the release of N2, NO or N2O.
(NH4) Cr2O7 → (t) N2 + Cr2O3 + 4H2O
NH4NO3 → (t) N2O + 2H2O
2NH4NO3 → (t) N2 + 2NO + 4H2O
NH4NO2 → (t) N2 + 2H2O
2NH4MnO4 → (t) N2 + 2MnO2 + 4H2O
3. Salts of carbonic acid
Almost all carbonates decompose to metal oxide and CO2. Alkali metal carbonates other than lithium do not decompose when heated. Silver and mercury carbonates decompose to free metal.
MeCO3 → (t) MeO + CO2
2Ag2CO3 → (t) 4Ag + 2CO2 + O2
All hydrocarbons are decomposed to the corresponding carbonate.
MeHCO3 → (t) MeCO3 + CO2 + H2O
4. Sulfurous acid salts
When heated, sulfites disproportionate, forming sulfide and sulfate. The sulfide (NH4) 2S formed during the decomposition of (NH4) 2SO3 immediately decomposes into NH3 and H2S.
MeSO3 → (t) MeS + MeSO4
(NH4) 2SO3 → (t) 2NH3 + H2S + 3 (NH4) 2SO4
Hydrosulfites decompose to sulfites, SO2 and H2O.
MeHSO3 → (t) MeSO3 + SO2 + H2O
5. Sulfuric acid salts
Many sulfates decompose at t> 700-800 C to metal oxide and SO3, which decomposes to SO2 and O2 at this temperature. Sulfates of alkali metals are heat-resistant. Silver and mercury sulfates decompose to free metal. Hydrosulfates decompose first to disulfates and then to sulfates.
2CaSO4 → (t) 2CaO + 2SO2 + O2
2Fe2 (SO4) 3 → (t) 2Fe2O3 + 6SO2 + 3O2
2FeSO4 → (t) Fe2O3 + SO3 + SO2
Ag2SO4 → (t) 2Ag + SO2 + O2
MeHSO4 → (t) MeS2O7 + H2O
MeS2O7 → (t) MeSO4 + SO3
6. Complex salts
Hydroxo complexes of amphoteric metals decompose mainly into medium salt and water.
K → (t) KAlO2 + 2H2O
Na2 → (t) ZnO + 2NaOH + H2O
7. Basic salts
Many basic salts decompose when heated. Basic salts of anoxic acids decompose into water and oxosalts
Al (OH) 2Br → (t) AlOBr + H2O
2AlOHCl2 → (t) Al2OCl4 + H2O
2MgOHCl → (t) Mg2OCl2 + H2O
Basic salts of oxygen-containing acids decompose into metal oxide and thermal decomposition products of the corresponding acid.
2AlOH (NO3) 2 → (t) Al2O3 + NO2 + 3O2 + H2O
(CuOH) 2CO3 → (t) 2CuO + H2O + CO2
8. Examples of thermal decomposition of other salts
4K2Cr2O7 → (t) 4K2CrO4 + 2Cr2O3 + 3O2
2KMnO4 → (t) K2MnO4 + MnO2 + O2
KClO4 → (t) KCl + O2
4KClO3 → (t) KCl + 3KClO4
2KClO3 → (t) 2KCl + 3O2
2NaHS → (t) Na2S + H2S
2CaHPO4 → (t) Ca2P2O7 + H2O
Ca (H2PO4) 2 → (t) Ca (PO3) 2 + 2H2O
2AgBr → (hν) 2Ag + Br2 (= AgI)
Most of the material presented was taken from the manual by N.E.Deryabina. "Chemistry. The main classes of inorganic substances". IPO "At Nikitskiye Vorota" Moscow 2011.
Classification of substances All substances can be divided into simple ones consisting of atoms of one element and complex ones consisting of atoms of various elements. Simple substances are divided into metals and non-metals: Metals - s and d elements. Non-metals - p elements. Complex substances are divided into organic and inorganic.
The properties of metals are determined by the ability of atoms to donate their electrons. The characteristic type of chemical bond for metals is metal bond... It is characterized by such physical properties: malleability, ductility, thermal conductivity, electrical conductivity. At indoor conditions all metals except mercury are solid.
The properties of non-metals are determined by the ability of atoms to easily accept electrons and poorly give their own. Non-metals have physical properties opposite to metals: their crystals are brittle, there is no "metallic" luster, low values of thermal and electrical conductivity. Some non-metals are gaseous under room conditions.
Classification organic compounds... By the structure of the carbon skeleton: Saturated / unsaturated Linear / branched / cyclic By the presence of functional groups: Alcohols Acids Ethers and esters Carbohydrates Aldehydes and ketones
Oxides are complex substances, the molecules of which are composed of two elements, one of which is oxygen in the -2 oxidation state. Oxides are divided into salt-forming and non-salt-forming (indifferent). Salt-forming oxides are divided into basic, acidic and amphoteric.
Basic oxides are oxides that form salts in reactions with acids or acidic oxides. Basic oxides are formed by metals with a low oxidation state (+1, +2) - these are elements of the 1st and 2nd groups of the periodic table. Examples of basic oxides: Na 2 O, Ca. O, Mg. O, Cu. O. Examples of salt formation reactions: Cu. O + 2 HCl Cu. Cl 2 + H 2 O, Mg. O + CO 2 Mg. CO 3.
Basic oxides Oxides of alkali and alkaline earth metals react with water to form bases: Na 2 O + H 2 O 2 Na. OH Ca. O + H 2 O Ca (OH) 2 Oxides of other metals do not react with water, the corresponding bases are obtained indirectly.
Acidic oxides are oxides that react with bases or basic oxides to form salts. Acidic oxides are formed by elements - non-metals and d - elements in high oxidation states (+5, +6, +7). Examples of acidic oxides: N 2 O 5, SO 3, CO 2, Cr. O 3, V 2 O 5. Examples of reactions of acid oxides: SO 3 + 2 KOH K 2 SO 4 + H 2 O Ca. O + CO 2 Ca. CO 3
Acid oxides Some acid oxides react with water to form the corresponding acids: SO 3 + H 2 OH 2 SO 4 N 2 O 5 + H 2 O 2 HNO 3 Other acid oxides do not react directly with water (Si. O 2, Te. O 3, Mo. O 3, WO 3), the corresponding acids are obtained indirectly. One way to obtain acidic oxides is to remove water from the corresponding acids. Therefore, acidic oxides are sometimes referred to as "anhydrides".
Amphoteric oxides have the properties of both acidic and basic oxides. With strong acids such oxides react as basic, and with strong bases as acidic: Sn. O + H 2 SO 4 Sn. SO 4 + H 2 O Sn. O + 2 KOH + H 2 O K 2
Methods for producing oxides Oxidation simple substances: 4 Fe + 3 O 2 2 Fe 2 O 3, S + O 2 SO 2. Combustion of complex substances: CH 4 + 2 O 2 CO 2 + 2 H 2 O, 2 SO 2 + O 2 2 SO 3. Thermal decomposition salts, bases and acids. Examples respectively: Ca. CO 3 Ca. O + CO 2, Cd (OH) 2 Cd. O + H 2 O, H 2 SO 4 SO 3 + H 2 O.
Nomenclature of oxides The name of an oxide is constructed according to the formula "oxide + name of the element in the genitive case". If an element forms several oxides, then the oxidation state of the element is indicated in brackets after the name. For example: CO - carbon monoxide (II), CO 2 - carbon monoxide (IV), Na 2 O - sodium oxide. Sometimes, instead of the oxidation state, the name indicates the number of oxygen atoms: monoxide, dioxide, trioxide, etc.
Hydroxides are compounds containing a hydroxyl group (-OH). Depending on the strength of the bonds in row E-O-H hydroxides are divided into acids and bases: Acids have the weakest O-H communication, therefore, during their dissociation, E-O- and H + are formed. The bases have the weakest communication E-O, therefore, during dissociation, E + and OH- are formed. In amphoteric hydroxides, either of these two bonds can be broken, depending on the nature of the substance with which the hydroxide reacts.
Acids The term "acid" within the framework of the theory of electrolytic dissociation has the following definition: Acids are substances that dissociate in solutions with the formation of hydrogen cations and anions of the acid residue. HA H ++ A Acids are divided into strong and weak (according to their ability to dissociate), one-, two-, and tri-basic (according to the number of hydrogen atoms contained) and oxygen-containing and anoxic. For example: H 2 SO 4 - strong, dibasic, oxygen-containing.
Chemical properties of acids 1. Interaction with bases with the formation of salt and water (neutralization reaction): H 2 SO 4 + Cu (OH) 2 Cu. SO 4 + 2 H 2 O. 2. Interaction with basic and amphoteric oxides with the formation of salts and water: 2 HNO 3 + Mg. O Mg (NO 3) 2 + H 2 O, H 2 SO 4 + Zn. O Zn. SO 4 + H 2 O.
Chemical properties of acids 3. Interaction with metals. Metals in the “Stress Row” up to hydrogen displace hydrogen from acid solutions (except for nitric and concentrated sulfuric acids); this forms a salt: Zn + 2 HCl Zn. Cl 2 + H 2 Metals that are in the “Series of stresses” after hydrogen, hydrogen from acid solutions do not displace Cu + 2 HCl ≠.
Chemical properties of acids 4. Some acids decompose when heated: H 2 Si. O 3 H 2 O + Si. O 2 5. Less volatile acids displace more volatile acids from their salts: H 2 SO 4 conc + Na. Cltv Na. HSO 4 + HCl 6. Stronger acids displace less strong acids from solutions of their salts: 2 HCl + Na 2 CO 3 2 Na. Cl + H 2 O + CO 2
Nomenclature of acids The names of anoxic acids are formed by adding to the root of the Russian name of the acid-forming element (or to the name of a group of atoms, for example, CN - cyan, CNS - rhodane) the suffix "-o", the ending "hydrogen" and the word "acid". For example: HCl - hydrochloric acid H 2 S - hydrosulfuric acid HCN - hydrocyanic acid
Nomenclature of acids Oxygenated acids are named according to the formula "element name" + "ending" + "acid". The ending varies depending on the oxidation state of the acid-forming element. The endings "-new" / "-nay" are used for higher oxidation states. HCl. O 4 - perchloric acid. Then the ending "-owat" is used. HCl. O 3 - chloric acid. Then the ending "-sure" is used. HCl. O 2 - chlorous acid. Finally, the last ending is "oily" HCl. O is hypochlorous acid.
Nomenclature of acids If an element forms only two oxygen-containing acids (for example, sulfur), then for the highest oxidation state the ending “–voy” / “naya” is used, and for the lower one, the ending “-pure”. Example for sulfur acids: H 2 SO 4 - sulfuric acid H 2 SO 3 - sulfurous acid
Nomenclature of acids If one acidic oxide attaches a different number of water molecules to form an acid, then an acid containing large quantity water is denoted by the prefix "ortho-", and the lesser "meta-". P 2 O 5 + H 2 O 2 HPO 3 - metaphosphoric acid P 2 O 5 + 3 H 2 O 2 H 3 PO 4 - orthophosphoric acid.
Bases The term "base" within the framework of the theory of electrolytic dissociation has the following definition: Bases are substances that dissociate in solutions to form hydroxide ions (OH‾) and metal ions. Bases are classified into weak and strong (according to their ability to dissociate), into one-, two-, three-acid (according to the number of hydroxo groups that can be replaced by an acid residue) into soluble (alkalis) and insoluble (according to the ability to dissolve in water). For example, KOH is strong, one-acid, soluble.
Chemical properties of bases 1. Interaction with acids: Ca (OH) 2 + H 2 SO 4 Ca. SO 4 + H 2 O 2. Interaction with acid oxides: Ca (OH) 2 + CO 2 Ca. CO 3 + H 2 O 3. Interaction with amphoteric oxides: 2 KOH + Sn. O + H 2 O K 2
Chemical properties of bases 4. Interaction with amphoteric bases: 2 Na. OH + Zn (OH) 2 Na 2 5. Thermal decomposition of bases with the formation of oxides and water: Ca (OH) 2 Ca. O + H 2 O. Hydroxides of alkali metals do not decompose when heated. 6. Interaction with amphoteric metals (Zn, Al, Pb, Sn, Be): Zn + 2 Na. OH + 2 H 2 O Na 2 + H 2
Base nomenclature The base name is formed by the formula "hydroxide" + "metal name in genitive". If an element forms several hydroxides, then its oxidation state is indicated in parentheses. For example Cr (OH) 2 - chromium (II) hydroxide, Cr (OH) 3 - chromium (III) hydroxide. Sometimes the name of the prefix to the word "hydroxide" indicates the number of hydroxyl groups - monohydroxide, dihydroxide, trihydroxide, etc.
Salts The term "base" in the framework of the theory of electrolytic dissociation has the following definition: Salts are substances that dissociate in solutions or melts to form positively charged ions other than hydrogen ions and negatively charged ions other than hydroxide ions. Salts are considered as a product of partial or complete substitution of hydrogen atoms for metal atoms or hydroxo groups for an acid residue. If the substitution occurs completely, then a normal (medium) salt is formed. If the substitution occurs partially, then such salts are called acidic (there are hydrogen atoms), or basic (there are hydroxyl groups).
Chemical properties of salts 1. Salts enter into ion exchange reactions if a precipitate is formed, a weak electrolyte or gas is released: salts react with alkalis, the metal cations of which correspond to insoluble bases: Cu. SO 4 + 2 Na. OH Na 2 SO 4 + Cu (OH) 2 ↓ salts interact with acids: a) whose cations form an insoluble salt with the new acid anion: Ba. Cl 2 + H 2 SO 4 Ba. SO 4 ↓ + 2 HCl b) whose anions correspond to an unstable carbonic acid or some volatile acid (in the latter case, the reaction is carried out between a solid salt and a concentrated acid): Na 2 CO 3 + 2 HCl 2 Na. Cl + H 2 O + CO 2, Na. Cltw + H 2 SO 4 conc Na. HSO 4 + HCl;
Chemical properties of salts c) which anions correspond to poorly soluble acid: Na 2 Si. O 3 + 2 HCl H 2 Si. O 3 ↓ + 2 Na. Cl d) whose anions correspond to a weak acid: 2 CH 3 COONa + H 2 SO 4 Na 2 SO 4 + 2 CH 3 COOH 2.Salts interact with each other if one of the new salts formed is insoluble or decomposes (completely hydrolyzes) with the release of gas or sediment: Ag. NO 3 + Na. Cl Na. NO 3+ Ag. Cl ↓ 2 Al. Cl 3 + 3 Na 2 CO 3 + 3 H 2 O 2 Al (OH) 3 ↓ + 6 Na. Cl + 3 CO 2
Chemical properties of salts 3. Salts can interact with metals if the metal to which the salt cation corresponds is in the “Stress Row” to the right of the reacting free metal (the more active metal displaces the less active metal from the solution of its salt): Zn + Cu. SO 4 Zn. SO 4 + Cu 4. Some salts decompose when heated: Ca. CO 3 Ca. O + CO 2 5. Some salts can react with water and form crystalline hydrates: Cu. SO 4 + 5 H 2 O Cu. SO 4 * 5 H 2 O
Chemical properties of salts 6. Salts undergo hydrolysis. This process will be discussed in detail in further lectures. 7. The chemical properties of acidic and basic salts differ from the properties of medium salts in that acidic salts also enter into all reactions characteristic of acids, and basic salts enter into all reactions characteristic of bases. For example: Na. HSO 4 + Na. OH Na 2 SO 4 + H 2 O, Mg. OHCl + HCl Mg. Cl 2 + H 2 O.
Salt preparation 1. Interaction of basic oxide with acid: Cu. O + H 2 SO 4 Cu. SO 4 + H 2 O 2. Interaction of a metal with a salt of another metal: Mg + Zn. Cl 2 Mg. Cl 2 + Zn 3. Interaction of metal with acid: Mg + 2 HCl Mg. Cl 2 + H 2 4. Reaction of the base with acid oxide: Ca (OH) 2 + CO 2 Ca. CO 3 + H 2 O 5. Reaction of base with acid: Fe (OH) 3 + 3 HCl Fe. Cl 3 + 3 H 2 O
Getting salts 6. Interaction of salt with base: Fe. Cl 2 + 2 KOH Fe (OH) 2 + 2 KCl 7. Interaction of two salts: Ba (NO 3) 2 + K 2 SO 4 Ba. SO 4 + 2 KNO 3 8. Interaction of metal with non-metal: 2 K + S K 2 S 9. Interaction of acid with salt: Ca. CO 3 + 2 HCl Ca. Cl 2 + H 2 O + CO 2 10. Interaction of acidic and basic oxides: Ca. O + CO 2 Ca. CO 3
Salt nomenclature The name of the average salt is formed according to the following rule: "the name of the acid residue in the nominative case" + "the name of the metal in the genitive". If the metal can be part of the salt in several oxidation states, then the oxidation state is indicated in brackets after the name of the salt.
Names of acid residues. For anoxic acids, the name of the acid residue consists of the root of the Latin name of the element and the ending "id". For example: Na 2 S- sodium sulfide, Na. Cl is sodium chloride. For oxygen-containing acids, the name of the residue consists of the root of the Latin name and several variants of the endings.
Names of acid residues. For the acid residue from elements in the highest oxidation state, the ending "at" is used. Na 2 SO 4 - sodium sulfate. For an acidic residue with a lower oxidation state (-pure acid), the ending "-it" is used. Na 2 SO 3 - sodium sulfite. For an acidic residue with an even lower oxidation state (-oviscous acid), the prefix "hippo" and the ending "-it" are used. Na. Cl. O - sodium hypochlorite.
Names of acid residues. Some acidic residues are called historical names Na. Cl. O 4 - sodium perchlorate. The prefix "hydro" is added to the name of acidic salts, followed by another prefix indicating the number of unsubstituted (remaining) hydrogen atoms. For example Na. H 2 PO 4 - sodium dihydrogen phosphate. Similarly, the prefix "hydroxo" is added to the name of the metal of basic salts. For example, Cr (OH) 2 NO 3 is dihydroxochrome (III) nitrate.
Names and formulas of acids and their residues Acid formula Acid residue Name of acid residue 2 3 4 Nitric HNO 3 ‾ nitrate Nitrous HNO 2 ‾ nitrite Hydrobromic HBr Br ‾ bromide Hydrogen iodide HI I‾ iodide Silicon H 2 Si. O 32¯ silicate Manganese HMn. O 4¯ permanganate Manganese H 2 Mn. O 42¯ manganate Metaphosphoric HPO 3¯H 3 As. O 43¯ Name of acid 1 Arsenic metaphosphate arsenate
Acid formula Arsenous H 3 As. O 3 Orthophosphoric H 3 PO 4 Name of acid Pyrophosphoric H 4 P 2 O 7 Bichromic Rhodanic hydrogen Sulphurous Phosphorous Hydrofluoric (hydrofluoric) Hydrogen chloride (hydrochloric) Chloric Chloric Chloride Hypochlorous Chromic Hydrogen cyanide (hydrochloric acid) H 2 H 2 Cr SO 3 H 3 PO 3 Acidic Name of the acidic residue of the residue As. O 33¯ arsenite PO 43¯ orthophosphate (phosphate) pyrophosphate P 2 O 7 4 ¯ (diphosphate) Cr 2 O 72¯ dichromate CNS¯ thiocyanate SO 42¯ sulfate SO 32¯ sulfite PO 33¯ phosphite HF F¯ HCl. O 4 HCl. O 3 HCl. O 2 HCl. O H 2 Cr. O 4 Cl¯ Cl. O 4¯ Cl. O 3¯ Cl. O 2¯ Cl. O¯ Cr. O 42¯ HCN CN¯ fluoride chloride perchlorate chlorite hypochlorite chromate cyanide