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Titles |
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Metaaluminum |
Metaaluminate |
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Metaarsenic |
Metaarsenate |
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orthoarsenic |
orthoarsenate |
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Metaarsenic |
Metaarsenite |
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orthoarsenic |
orthoarsenite |
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metabornaya |
Metaborate |
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orthoborn |
orthoborate |
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Tetrahedral |
tetraborate |
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Hydrogen bromide | ||
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Bromous |
Hypobromite |
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bromine | ||
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Formic | ||
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Acetic | ||
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Hydrogen cyanide | ||
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Coal |
Carbonate |
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sorrel | ||
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Hydrogen chloride | ||
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hypochlorous |
Hypochlorite |
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Chloride | ||
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Chlorine | ||
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Perchlorate |
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metachromic |
Metachromite |
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Chrome | ||
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double chrome |
dichromate |
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Hydrogen iodine | ||
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Iodineous |
Hypoioditis |
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Iodine | ||
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Periodat |
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manganese |
Permanganate |
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manganese |
manganate |
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molybdenum |
Molybdate |
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Hydrogen azidide (hydrazoic) | ||
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nitrogenous | ||
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Metaphosphoric |
Metaphosphate |
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orthophosphoric |
orthophosphate |
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Diphosphoric (pyrophosphoric) |
Diphosphate (pyrophosphate) |
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Phosphorous | ||
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Phosphorous |
Hypophosphite |
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hydrogen sulfide | ||
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Rhodohydrogen | ||
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sulphurous | ||
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Thiosulphuric |
thiosulfate |
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Two-sulfur (pyrosulfur) |
Disulfate (pyrosulfate) |
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Peroxo-two-sulphuric (nadsulphuric) |
Peroxodisulfate (persulfate) |
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hydrogen selenium | ||
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selenist | ||
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Selenic | ||
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Silicon | ||
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Vanadium | ||
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Tungsten |
tungstate |
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salt – substances that can be considered as the product of substitution of hydrogen atoms in an acid by metal atoms or a group of atoms. There are 5 types of salts: medium (normal), acidic, basic, double, complex, differing in the nature of the ions formed during dissociation.
1.Medium salts are products of complete substitution of hydrogen atoms in the molecule acids. Salt composition: cation - metal ion, anion - acid residue ion. Na 2 CO 3 - sodium carbonate
Na 3 PO 4 - sodium phosphate
Na 3 RO 4 \u003d 3Na + + RO 4 3-
cation anion
2. Acid salts - products of incomplete substitution of hydrogen atoms in the acid molecule. The anion contains hydrogen atoms.
NaH 2 RO 4 \u003d Na + + H 2 RO 4 -
Dihydrogen phosphate cation anion
Acid salts give only polybasic acids, with an insufficient amount of base taken.
H 2 SO 4 + NaOH \u003d NaHSO 4 + H 2 O
hydrosulphate
By adding an excess of alkali, the acid salt can be converted into a medium
NaHSO 4 + NaOH \u003d Na 2 SO 4 + H 2 O
3.Basic salts - products of incomplete replacement of hydroxide ions in the base by an acid residue. The cation contains a hydroxo group.
CuOHCl=CuOH + +Cl -
hydroxochloride cation anion
Basic salts can only be formed by polyacid bases.
(bases containing several hydroxyl groups), when they interact with acids.
Cu(OH) 2 + HCl \u003d CuOHCl + H 2 O
You can convert the basic salt to the middle one by acting on it with acid:
CuOHCl + HCl \u003d CuCl 2 + H 2 O
4.Double salts - they include cations of several metals and anions of one acid
KAl(SO 4) 2 = K + + Al 3+ + 2SO 4 2-
potassium aluminum sulfate
Characteristic properties all considered types of salts are: exchange reactions with acids, alkalis and with each other.
For naming salts use Russian and international nomenclature.
The Russian name of the salt is made up of the name of the acid and the name of the metal: CaCO 3 - calcium carbonate.
For acidic salts, an “acidic” additive is introduced: Ca (HCO 3) 2 - acidic calcium carbonate. For the name of the basic salts, the additive is “basic”: (СuOH) 2 SO 4 - basic copper sulfate.
The most widespread is the international nomenclature. The name of the salt according to this nomenclature consists of the name of the anion and the name of the cation: KNO 3 - potassium nitrate. If the metal has a different valency in the compound, then it is indicated in brackets: FeSO 4 - iron sulfate (III).
For salts of oxygen-containing acids, the suffix “at” is introduced in the name if the acid-forming element exhibits the highest valence: KNO 3 - potassium nitrate; the suffix "it" if the acid-forming element exhibits a lower valence: KNO 2 - potassium nitrite. In cases where an acid-forming element forms acids in more than two valence states, the suffix "at" is always used. Moreover, if it shows the highest valency, add the prefix "per". For example: KClO 4 - potassium perchlorate. If the acid-forming element forms a lower valency, the suffix "it" is used, with the addition of the prefix "hypo". For example: KClO– potassium hypochlorite. For salts formed by acids containing different amounts of water, the prefixes "meta" and "ortho" are added. For example: NaPO 3 - sodium metaphosphate (salt of metaphosphoric acid), Na 3 PO 4 - sodium orthophosphate (salt of orthophosphoric acid). In the name of the acid salt, the prefix "hydro" is introduced. For example: Na 2 HPO 4 - sodium hydrogen phosphate (if there is one hydrogen atom in the anion) and the prefix "hydro" with a Greek numeral (if there are more than one hydrogen atoms) -NaH 2 PO 4 - sodium dihydrogen phosphate. The prefix "hydroxo" is introduced into the names of the basic salts. For example: FeOHCl - hydroxide iron chloride (P).
5. Complex salts - compounds that form complex ions (charged complexes) during dissociation. When writing complex ions, it is customary to enclose them in square brackets. For example:
Ag (NH 3) 2 Cl \u003d Ag (NH 3) 2 + + Cl -
K 2 PtCl 6 \u003d 2K + + PtCl 6 2-
According to the ideas proposed by A. Werner, in a complex compound, internal and external spheres are distinguished. So, for example, in the considered complex compounds, the inner sphere is made up of complex ions Ag (NH 3) 2 + and PtCl 6 2-, and the outer sphere, respectively, Cl - and K + . The central atom or ion of the inner sphere is called the complexing agent. In the proposed compounds, these are Ag +1 and Pt +4. Molecules or ions of the opposite sign coordinated around the complexing agent are ligands. In the compounds under consideration, these are 2NH 3 0 and 6Cl -. The number of ligands of a complex ion determines its coordination number. In the proposed compounds, it is respectively equal to 2 and 6.
According to the sign of the electric charge, complexes are distinguished
1.Cationic (coordination around the positive ion of neutral molecules):
Zn +2 (NH 3 0) 4 Cl 2 -1; Al +3 (H 2 O 0) 6 Cl 3 -1
2.Anionic (coordination around a complexing agent in a positive oxidation state of a ligand having a negative oxidation state):
K 2 +1 Be +2 F 4 -1 ; K 3 +1 Fe +3 (CN -1) 6
3. Neutral complexes - complex compounds without an outer spherePt + (NH 3 0) 2 Cl 2 - 0. Unlike compounds with anionic and cationic complexes, neutral complexes are not electrolytes.
Dissociation of complex compounds into the inner and outer spheres is called primary . It flows almost completely like strong electrolytes.
Zn (NH 3) 4 Cl 2 → Zn (NH 3) 4 +2 + 2Cl ─
K 3 Fe(CN) 6 → 3 K + +Fe(CN) 6 3 ─
Complex ion (charged complex) in a complex compound it forms the inner coordination sphere, the remaining ions form the outer sphere.
In the K 3 complex compound, the 3- complex ion, consisting of the complexing agent - the Fe 3+ ion and the ligands - the CN ions - ions, is the inner sphere of the compound, and the K + ions form the outer sphere.
The ligands located in the inner sphere of the complex are bound by the complexing agent much more strongly and their cleavage during dissociation takes place only to a small extent. The reversible dissociation of the inner sphere of a complex compound is called secondary .
Fe(CN) 6 3 ─ Fe 3+ + 6CN ─
The secondary dissociation of the complex proceeds according to the type of weak electrolytes. The algebraic sum of the charges of particles formed during the dissociation of a complex ion is equal to the charge of the complex.
The names of complex compounds, as well as the names of ordinary substances, are formed from the Russian names of cations and the Latin names of anions; just as in ordinary substances, in complex compounds the anion is called first. If the anion is complex, its name is formed from the name of the ligands with the ending “o” (Cl - - chloro, OH - hydroxo, etc.) and the Latin name of the complexing agent with the suffix “at”; the number of ligands is usually indicated by the corresponding numeral. If the complexing agent is an element capable of exhibiting a variable oxidation state, the numerical value of the oxidation state, as in the names of ordinary compounds, is indicated by a Roman numeral in parentheses
Example: Names of complex compounds with a complex anion.
K 3 - potassium hexacyanoferrate (III)
Complex cations in the vast majority of cases contain neutral molecules of water H 2 O, called “aqua,” or ammonia NH 3, called “ammine,” as ligands. In the first case, complex cations are called aquacomplexes, in the second - ammoniates. The name of the complex cation consists of the name of the ligands, indicating their number, and the Russian name of the complexing agent, with the indicated value of its oxidation state, if necessary.
Example: Names of complex compounds with a complex cation.
Cl 2 - tetrammine zinc chloride
Complexes, despite their stability, can be destroyed in reactions in which ligands are bound into even more stable weakly dissociating compounds.
Example: Destruction of a hydroxo complex by an acid due to the formation of weakly dissociating H 2 O molecules.
K 2 + 2H 2 SO 4 \u003d K 2 SO 4 + ZnSO 4 + 2H 2 O.
Name of the complex compound they begin with the composition of the inner sphere, then they name the central atom and the degree of its oxidation.
In the inner sphere, anions are first named, adding the ending "o" to the Latin name.
F -1 - fluoro Cl - - chloroCN - - cyanoSO 2 -2 - sulfito
OH - - hydroxoNO 2 - - nitrite, etc.
Then the neutral ligands are called:
NH 3 - ammine H 2 O - aqua
The number of ligands is marked with Greek numerals:
I - mono (as a rule, not indicated), 2 - di, 3 - three, 4 - tetra, 5 - penta, 6 - hexa. Next, they pass to the name of the central atom (complexing agent). This takes into account the following:
If the complexing agent is part of the cation, then the Russian name of the element is used and the degree of its oxidation is indicated in brackets in Roman numerals;
If the complexing agent is part of the anion, then the Latin name of the element is used, the degree of its oxidation is indicated in front of it, and the ending - “at” is added at the end.
After the designation of the inner sphere, indicate the cations or anions located in the outer sphere.
When forming the name of a complex compound, it must be remembered that the ligands that make up its composition can be mixed: electrically neutral molecules and charged ions; or charged ions of various kinds.
Ag +1 NH 3 2 Cl– diamine-silver (I) chloride
K 3 Fe +3 CN 6 - hexacyano (Ш) potassium ferrate
NH 4 2 Pt +4 OH 2 Cl 4 – dihydroxotetrachloro (IV) ammonium platinate
Pt +2 NH 3 2 Cl 2 -1 o - diammine dichloride-platinum x)
X) in neutral complexes, the name of the complexing agent is given in the nominative case
acids- complex substances consisting of one or more hydrogen atoms that can be replaced by metal atoms, and acid residues.
Acid classification
1. According to the number of hydrogen atoms: number of hydrogen atoms ( n ) determines the basicity of acids:
n= 1 single base
n= 2 dibasic
n= 3 tribasic
2. By composition:
a) Table of oxygen containing acids, acid residues and corresponding acid oxides:
|
Acid (H n A) |
Acid residue (A) |
Corresponding acid oxide |
|
H 2 SO 4 sulfuric |
SO 4 (II) sulfate |
SO 3 sulfur oxide (VI) |
|
HNO 3 nitric |
NO 3 (I) nitrate |
N 2 O 5 nitric oxide (V) |
|
HMnO 4 manganese |
MnO 4 (I) permanganate |
Mn2O7 manganese oxide ( VII) |
|
H 2 SO 3 sulfurous |
SO 3 (II) sulfite |
SO 2 sulfur oxide (IV) |
|
H 3 PO 4 orthophosphoric |
PO 4 (III) orthophosphate |
P 2 O 5 phosphorus oxide (V) |
|
HNO 2 nitrogenous |
NO 2 (I) nitrite |
N 2 O 3 nitric oxide (III) |
|
H 2 CO 3 coal |
CO 3 (II) carbonate |
CO2 carbon monoxide ( IV) |
|
H 2 SiO 3 silicon |
SiO 3 (II) silicate |
SiO 2 silicon oxide (IV) |
|
HClO hypochlorous |
СlO(I) hypochlorite |
C l 2 O chlorine oxide (I) |
|
HClO 2 chloride |
Сlo 2 (I) chlorite |
C l 2 O 3 chlorine oxide (III) |
|
HClO 3 chloric |
СlO 3 (I) chlorate |
C l 2 O 5 chlorine oxide (V) |
|
HClO 4 chloride |
СlO 4 (I) perchlorate |
С l 2 O 7 chlorine oxide (VII) |
b) Table of anoxic acids
|
Acid (N n A) |
Acid residue (A) |
|
HCl hydrochloric, hydrochloric |
Cl(I) chloride |
|
H 2 S hydrogen sulfide |
S(II) sulfide |
|
HBr hydrobromic |
Br(I) bromide |
|
HI hydroiodic |
I(I) iodide |
|
HF hydrofluoric, hydrofluoric |
F(I) fluoride |
Physical properties of acids
Many acids, such as sulfuric, nitric, hydrochloric, are colorless liquids. solid acids are also known: orthophosphoric, metaphosphoric HPO 3 , boric H 3 BO 3 . Almost all acids are soluble in water. An example of an insoluble acid is silicic H2SiO3 . Acid solutions have a sour taste. So, for example, many fruits give a sour taste to the acids they contain. Hence the names of acids: citric, malic, etc.
Methods for obtaining acids
|
anoxic |
oxygen-containing |
|
HCl, HBr, HI, HF, H2S |
HNO 3 , H 2 SO 4 and others |
|
RECEIVING |
|
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1. Direct interaction of non-metals H 2 + Cl 2 \u003d 2 HCl |
1. Acid oxide + water = acid SO 3 + H 2 O \u003d H 2 SO 4 |
|
2. Exchange reaction between salt and less volatile acid 2 NaCl (tv.) + H 2 SO 4 (conc.) \u003d Na 2 SO 4 + 2HCl |
|
Chemical properties of acids
1. Change the color of the indicators
|
Name of the indicator |
Neutral environment |
acid environment |
|
Litmus |
Violet |
Red |
|
Phenolphthalein |
Colorless |
Colorless |
|
Methyl orange |
Orange |
Red |
|
Universal indicator paper |
orange |
Red |
2. React with metals in the activity series up to H 2
(excl. HNO 3 -Nitric acid)
Video "Interaction of acids with metals"
Me + ACID \u003d SALT + H 2 (p. substitution)
Zn + 2 HCl \u003d ZnCl 2 + H 2
3. With basic (amphoteric) oxides – metal oxides
Video "Interaction of metal oxides with acids"
Me x O y + ACID \u003d SALT + H 2 O (p. exchange)
4. React with bases – neutralization reaction
ACID + BASE = SALT + H 2 O (p. exchange)
H 3 PO 4 + 3 NaOH = Na 3 PO 4 + 3 H 2 O
5. React with salts of weak, volatile acids - if an acid is formed that precipitates or a gas is released:
2 NaCl (tv.) + H 2 SO 4 (conc.) \u003d Na 2 SO 4 + 2HCl ( R . exchange )
Video "Interaction of acids with salts"
6. Decomposition of oxygen-containing acids when heated
(excl. H 2 SO 4 ; H 3 PO 4 )
ACID = ACID OXIDE + WATER (r. decomposition)
Remember!Unstable acids (carbonic and sulphurous) - decompose into gas and water:
H 2 CO 3 ↔ H 2 O + CO 2
H 2 SO 3 ↔ H 2 O + SO 2
Hydrosulphuric acid in products released as a gas:
CaS + 2HCl \u003d H 2 S+ CaCl2
TASKS FOR REINFORCEMENT
No. 1. Distribute the chemical formulas of acids in a table. Give them names:
LiOH , Mn 2 O 7 , CaO , Na 3 PO 4 , H 2 S , MnO , Fe (OH ) 3 , Cr 2 O 3 , HI , HClO 4 , HBr , CaCl 2 , Na 2 O , HCl , H 2 SO 4 , HNO 3 , HMnO 4 , Ca (OH ) 2 , SiO 2 , Acids
Bes-sour-
native
Oxygen-containing
soluble
insoluble
one-
main
two-core
tri-basic
No. 2. Write reaction equations:
Ca+HCl
Na + H 2 SO 4
Al + H 2 S
Ca + H 3 PO 4
Name the reaction products.
No. 3. Make the reaction equations, name the products:
Na 2 O + H 2 CO 3
ZnO + HCl
CaO + HNO3
Fe 2 O 3 + H 2 SO 4
No. 4. Make up the reaction equations for the interaction of acids with bases and salts:
KOH + HNO3
NaOH + H2SO3
Ca(OH) 2 + H 2 S
Al(OH)3 + HF
HCl + Na 2 SiO 3
H 2 SO 4 + K 2 CO 3
HNO 3 + CaCO 3
Name the reaction products.
SIMULATORS
Trainer number 1. "Formulas and names of acids"
Trainer number 2. "Correspondence: acid formula - oxide formula"
Safety Precautions - First Aid for Skin Contact with Acids
Safety -
Substances that dissociate in solutions to form hydrogen ions are called.
Acids are classified according to their strength, basicity, and the presence or absence of oxygen in the composition of the acid.
By strengthacids are divided into strong and weak. The most important strong acids are nitric HNO 3 , sulfuric H 2 SO 4 , and hydrochloric HCl .
By the presence of oxygen distinguish oxygen-containing acids ( HNO3, H3PO4 etc.) and anoxic acids ( HCl, H 2 S , HCN, etc.).
By basicity, i.e. according to the number of hydrogen atoms in an acid molecule that can be replaced by metal atoms to form a salt, acids are divided into monobasic (for example, HNO 3, HCl), dibasic (H 2 S, H 2 SO 4), tribasic (H 3 PO 4 ), etc.
The names of oxygen-free acids are derived from the name of the non-metal with the addition of the ending -hydrogen: HCl - hydrochloric acid, H 2 S e - hydroselenic acid, HCN - hydrocyanic acid.
The names of oxygen-containing acids are also formed from the Russian name of the corresponding element with the addition of the word "acid". At the same time, the name of the acid in which the element is in the highest oxidation state ends in "naya" or "ova", for example, H2SO4 - sulfuric acid, HClO 4 - perchloric acid, H 3 AsO 4 - arsenic acid. With a decrease in the degree of oxidation of the acid-forming element, the endings change in the following sequence: “oval” ( HClO 3 - chloric acid), "pure" ( HClO 2 - chlorous acid), "wobbly" ( H O Cl - hypochlorous acid). If the element forms acids, being in only two oxidation states, then the name of the acid corresponding to the lowest oxidation state of the element receives the ending "pure" ( HNO3 - Nitric acid, HNO 2 - nitrous acid).
Table - The most important acids and their salts
|
Acid |
Names of the corresponding normal salts |
|
|
Name |
Formula |
|
|
Nitrogen |
HNO3 |
Nitrates |
|
nitrogenous |
HNO 2 |
Nitrites |
|
Boric (orthoboric) |
H3BO3 |
Borates (orthoborates) |
|
Hydrobromic |
Bromides |
|
|
Hydroiodine |
iodides |
|
|
Silicon |
H2SiO3 |
silicates |
|
manganese |
HMnO 4 |
Permanganates |
|
Metaphosphoric |
HPO 3 |
Metaphosphates |
|
Arsenic |
H 3 AsO 4 |
Arsenates |
|
Arsenic |
H 3 AsO 3 |
Arsenites |
|
orthophosphoric |
H3PO4 |
Orthophosphates (phosphates) |
|
Diphosphoric (pyrophosphoric) |
H4P2O7 |
Diphosphates (pyrophosphates) |
|
dichrome |
H2Cr2O7 |
Dichromates |
|
sulfuric |
H2SO4 |
sulfates |
|
sulphurous |
H2SO3 |
Sulfites |
|
Coal |
H2CO3 |
Carbonates |
|
Phosphorous |
H3PO3 |
Phosphites |
|
Hydrofluoric (hydrofluoric) |
Fluorides |
|
|
Hydrochloric (hydrochloric) |
chlorides |
|
|
Chloric |
HClO 4 |
Perchlorates |
|
Chlorine |
HClO 3 |
Chlorates |
|
hypochlorous |
HClO |
Hypochlorites |
|
Chrome |
H2CrO4 |
Chromates |
|
Hydrogen cyanide (hydrocyanic) |
cyanides |
|
Obtaining acids
1. Anoxic acids can be obtained by direct combination of non-metals with hydrogen:
H 2 + Cl 2 → 2HCl,
H 2 + S H 2 S.
2. Oxygen-containing acids can often be obtained by directly combining acid oxides with water:
SO 3 + H 2 O \u003d H 2 SO 4,
CO 2 + H 2 O \u003d H 2 CO 3,
P 2 O 5 + H 2 O \u003d 2 HPO 3.
3. Both oxygen-free and oxygen-containing acids can be obtained by exchange reactions between salts and other acids:
BaBr 2 + H 2 SO 4 \u003d BaSO 4 + 2HBr,
CuSO 4 + H 2 S \u003d H 2 SO 4 + CuS,
CaCO 3 + 2HBr \u003d CaBr 2 + CO 2 + H 2 O.
4. In some cases, redox reactions can be used to obtain acids:
H 2 O 2 + SO 2 \u003d H 2 SO 4,
3P + 5HNO 3 + 2H 2 O = 3H 3 PO 4 + 5NO.
Chemical properties of acids
1. The most characteristic chemical property of acids is their ability to react with bases (as well as with basic and amphoteric oxides) to form salts, for example:
H 2 SO 4 + 2NaOH \u003d Na 2 SO 4 + 2H 2 O,
2HNO 3 + FeO \u003d Fe (NO 3) 2 + H 2 O,
2 HCl + ZnO \u003d ZnCl 2 + H 2 O.
2. The ability to interact with some metals in the series of voltages up to hydrogen, with the release of hydrogen:
Zn + 2HCl \u003d ZnCl 2 + H 2,
2Al + 6HCl \u003d 2AlCl 3 + 3H 2.
3. With salts, if a poorly soluble salt or volatile substance is formed:
H 2 SO 4 + BaCl 2 = BaSO 4 ↓ + 2HCl,
2HCl + Na 2 CO 3 \u003d 2NaCl + H 2 O + CO 2,
2KHCO 3 + H 2 SO 4 \u003d K 2 SO 4 + 2SO 2+ 2H2O.
Note that polybasic acids dissociate in steps, and the ease of dissociation in each of the steps decreases, therefore, for polybasic acids, acidic salts are often formed instead of medium salts (in the case of an excess of the reacting acid):
Na 2 S + H 3 PO 4 \u003d Na 2 HPO 4 + H 2 S,
NaOH + H 3 PO 4 = NaH 2 PO 4 + H 2 O.
4. A special case of acid-base interaction is the reaction of acids with indicators, leading to a change in color, which has long been used for the qualitative detection of acids in solutions. So, litmus changes color in an acidic environment to red.
5. When heated, oxygen-containing acids decompose into oxide and water (preferably in the presence of a water-removing P2O5):
H 2 SO 4 \u003d H 2 O + SO 3,
H 2 SiO 3 \u003d H 2 O + SiO 2.
M.V. Andryukhova, L.N. Borodin
Acids are complex substances whose molecules consist of hydrogen atoms (capable of being replaced by metal atoms) associated with an acid residue.
general characteristics
Acids are classified into oxygen-free and oxygen-containing, as well as organic and inorganic.
Rice. 1. Classification of acids - anoxic and oxygen-containing.
Anoxic acids are solutions in water of such binary compounds as hydrogen halides or hydrogen sulfide. In solution, the polar covalent bond between hydrogen and an electronegative element is polarized by the action of dipole water molecules, and the molecules break up into ions. the presence of hydrogen ions in the substance and allows you to call aqueous solutions of these binary compounds acids.
Acids are named after the name of the binary compound by adding the ending -naya. for example, HF is hydrofluoric acid. The acid anion is called by the name of the element by adding the ending -id, for example, Cl - chloride.
Oxygen-containing acids (oxoacids)- these are acid hydroxides dissociating according to the acid type, that is, as protoliths. Their general formula is E (OH) mOn, where E is a non-metal or a metal with variable valence in the highest oxidation state. provided that n is 0, then the acid is weak (H 2 BO 3 - boric), if n \u003d 1, then the acid is either weak or of medium strength (H 3 PO 4 - orthophosphoric), if n is greater than or equal to 2, then acid is considered strong (H 2 SO 4).
Rice. 2. Sulfuric acid.
Acid hydroxides correspond to acid oxides or acid anhydrides, for example, sulfuric acid corresponds to sulfuric anhydride SO 3 .
Chemical properties of acids
Acids have a number of properties that distinguish them from salts and other chemical elements:
- Action on indicators. How acid protolytes dissociate to form H+ ions, which change the color of the indicators: a purple litmus solution turns red, and an orange methyl orange solution turns pink. Polybasic acids dissociate in steps, and each subsequent stage is more difficult than the previous one, since increasingly weaker electrolytes dissociate in the second and third steps:
H 2 SO 4 \u003d H + + HSO 4 -
The color of the indicator depends on whether the acid is concentrated or diluted. So, for example, when litmus is lowered into concentrated sulfuric acid, the indicator turns red, but in dilute sulfuric acid, the color does not change.
- Neutralization reaction, that is, the interaction of acids with bases, resulting in the formation of salt and water, always occurs if at least one of the reagents is strong (base or acid). The reaction does not go if the acid is weak, the base is insoluble. For example, there is no reaction:
H 2 SiO 3 (weak, water-insoluble acid) + Cu (OH) 2 - no reaction
But in other cases, the neutralization reaction with these reagents goes:
H 2 SiO 3 + 2KOH (alkali) \u003d K 2 SiO 3 + 2H 2 O
- Interaction with basic and amphoteric oxides:
Fe 2 O 3 + 3H 2 SO 4 \u003d Fe 2 (SO 4) 3 + 3H 2 O
- The interaction of acids with metals, standing in a series of voltages to the left of hydrogen, leads to a process in which a salt is formed and hydrogen is released. This reaction is easy if the acid is strong enough.
Nitric acid and concentrated sulfuric acid react with metals by reducing not hydrogen, but the central atom:
Mg + H 2 SO 4 + MgSO 4 + H 2
- The interaction of acids with salts occurs if the result is a weak acid. If the salt that reacts with the acid is soluble in water, then the reaction will also proceed if an insoluble salt is formed:
Na 2 SiO 3 (soluble salt of a weak acid) + 2HCl (strong acid) \u003d H 2 SiO 3 (weak insoluble acid) + 2NaCl (soluble salt)
Many acids are used in industry, for example, acetic acid is necessary for preserving meat and fish products.
