What does the mutual influence of atoms give? Mutual influence of atoms in molecules of organic compounds
Acid salts - This salt, which are formed by incomplete replacement of atoms hydrogen atoms in acid molecules metals.They contain two types of cations: a metal (or ammonium) cation and a hydrogen cation, and a multicharged anion acid residue. Cation hydrogen gives the name of the salt the prefix “hydro”, for example, sodium bicarbonate. Such salts dissociate into aqueous solutions into metal cations, hydrogen cations and anions of acid residues. They are formed when there is excess acids and contain hydrogen atoms. Acid salts are formed only by polybasic acids and exhibit the properties of both salts and acids. Acid salts of strong acids (hydrogen sulfates, dihydrogen phosphates) upon hydrolysis give an acidic reaction to the medium (which is what their name is associated with). At the same time, solutions acid salts weak acids(bicarbonates, tartrates) may have a neutral or alkaline reaction.
Physical properties
Acid salts - solid crystalline substances, having different solubility, and characterized by high melting points. The color of salts depends on the metal included in their composition.
Chemical properties
1. Acid salts react with metals located in the series of standard electrode potentials (Beketov series) to the left of the hydrogen atom:
2KНSO 4 + Mg = H 2 + MgSO 4 + K 2 SO 4,
2NaHCO 3 + Fe = H 2 + Na 2 CO 3 + Fe 2 (CO 3) 3
Since these reactions occur in aqueous solutions, metals such as lithium, sodium, potassium, barium and others active metals, which under normal conditions react with water.
2. Acid salts react with acids if the resulting acid is weaker or more volatile than the reacting acid:
NaHCO 3 + HCl = NaCl + H 2 O + CO 2
To carry out such reactions, they usually take dry salt and treat it with concentrated acid.
3. Acidic salts react with aqueous solutions of alkalis to form a medium salt and water:
1) Ba(HCO 3) 2 + Ba(OH) 2 = 2BaCO 3 + 2H 2 O
2) 2KHSO 4 + 2NaOH = 2H 2 O + K 2 SO 4 + Na 2 SO 4,
3) NaHCO 3 + NaOH = H 2 O + Na 2 CO 3
Such reactions are used to obtain intermediate salts. 4. Acid salts react with salt solutions, if as a result of the reaction a precipitate forms, gas is released or water is formed:
1) 2KHSO 4 + MgCO 3 = H 2 O + CO 2 + K 2 SO 4 + MgSO 4,
2) 2KHSO 4 + BaCl 2 = BaSO 4 + K 2 SO 4 + 2HCl.
3) 2NaHCO 3 + BaCl 2 = BaCO 3 + Na 2 CO 3 + 2HCl
These reactions are used, among other things, to obtain practically insoluble salts.
5. Some acid salts decompose when heated:
1) Ca(HCO 3) 2 = CaCO 3 + CO 2 + H 2 O
2) 2NaHCO 3 = CO 2 + H 2 O + Na 2 CO 3
6. Acidic salts react with basic ones oxides with the formation of water and medium salts:
1) 2KHSO 4 + MgO = H 2 O + MgSO 4 + K 2 SO 4,
2) 2NaHCO 3 + CuO = H 2 O + CuCO 3 + Na 2 CO 3
7. When hydrolysis acid salts decompose into metal cations and acidic anions: KHSO 4 → K + + HSO 4–
The resulting acidic anions, in turn, reversibly dissociate: HSO 4– → H + + SO 4 2–
Receipt
Acid salts are formed when an excess acid reacts with an alkali. Depending on the number of moles of acid (in this case - orthophosphoric) dihydrogen orthophosphates can be formed (1) and hydroorthophosphates (2) :
Ba(OH) 2 + 2H 3 PO 4 → Ba(H 2 PO 4) 2 + 2H 2 O
Ba(OH) 2 + H 3 PO 4 → BaHPO 4 + 2H 2 O
When preparing acid salts, the molar ratios of the starting substances are important. For example, with a molar ratio of NaOH and H 2 SO 4 2:1, an average salt is formed:
2NaOH + H 2 SO 4 = Na 2 SO 4 + 2H 2 O And at a ratio of 1:1 - acidic: NaOH + H 2 SO 4 = NaHSO 4 + H 2 O
1. Acid salts are formed as a result of the interaction of acid solutions with metals that are in the activity series of metals to the left of hydrogen:
Zn + 2H 2 SO 4 = H 2 + Zn(HSO 4) 2,
2. Acid salts are formed as a result of the interaction of acids with basic oxides:
1) CaO + H 3 PO 4 = CaHPO 4 + H 2 O,
2) CuO + 2H 2 SO 4 = Cu(HSO 4) 2 + H 2 O
3. Acid salts are formed as a result of the interaction of acids with bases (neutralization reaction):
1) NaOH + H 2 SO 4 = NaHSO 4 + H 2 O
2) H 2 SO 4 + KOH = KHSO 4 + H 2 O
3) Mg(OH) 2 + 2H 2 SO 4 = Mg(HSO 4) 2 + 2H 2 O
Depending on the ratios of the concentrations of acids and bases involved in neutralization reactions, medium, acidic and basic salts can be obtained.
4. Acid salts can be obtained as a result of the interaction of acids and medium salts:
Ca 3 (PO 4) 2 + H 3 PO 4 = 3CaHPO 4
5. Acid salts are formed as a result of the interaction of bases with an excess of acidic oxide.
Salts - these are complex substances consisting of one (several) metal atoms (or more complex cationic groups, for example, ammonium groups N H 4 +, hydroxylated Me(OH) groups n m+ ) and one (several) acidic residues. General formula of salts Meh n A m , where A is the acid residue. Salt (from the point of view electrolytic dissociation) are electrolytes that dissociate in aqueous solutions into metal cations (or ammonium N H 4 +) and anions of the acid residue.
Classification. According to the composition of the salt, they are divided into average (normal ), sour(hydrosols ), basic (hydroxosalts) , double , mixed And complex(cm. table).
Table - Classification of salts by composition
| SALT | |||||
|
Average (normal) - product of complete replacement of hydrogen atoms in an acid with a metal AlCl3 |
Sour(hydrosols) - product of incomplete replacement of hydrogen atoms in an acid with a metal TO HSO 4 |
Basic(hydroxosalts) - product of incomplete replacement of the OH groups of a base with an acidic residue FeOHCl |
Double - contain two different metals and one acid residue TO NaSO4 |
Mixed - contain one metal and several acidic residues CaClBr |
Complex SO 4 |
Physical properties. Salts are crystalline substances of different colors and different solubility in water.
Chemical properties
1) Dissociation. Medium, double and mixed salts dissociate in one step. For acidic and basic salts, dissociation occurs in steps.
NaCl Na + + Cl – .
KNaSO 4 K + + Na + + SO 4 2– .
CaClBr Ca 2+ + Cl – + Br – .
KHSO 4 K + + HSO 4 – HSO 4 – H + + SO 4 2– .
FeOHCl FeOH + + Cl – FeOH + Fe 2+ + OH – .
SO 4 2+ + SO 4 2– 2+ Cu 2+ + 4NH 3 .
2) Interaction with indicators. As a result of hydrolysis, H + ions (acidic environment) or OH – ions (alkaline environment) accumulate in salt solutions. Soluble salts formed by at least one weak electrolyte undergo hydrolysis. Solutions of such salts interact with indicators:
indicator + H + (OH –) colored compound.
AlCl 3 + H 2 O AlOHCl 2 + HCl Al 3+ + H 2 O AlOH 2+ + H +
3) Heat decomposition. When some salts are heated, they decompose into a metal oxide and an acid oxide:
CaCO 3 CaO + CO 2 .
When heated, some oxygen-free acids can decompose into simple substances:
2AgCl Ag + Cl 2 .
Salts formed by oxidizing acids are more difficult to decompose:
2K NO 3 2K NO 2 + O 2.
4) Interaction with acids: A reaction occurs if the salt is formed by a weaker or volatile acid, or if a precipitate is formed.
2HCl + Na 2 CO 3 ® 2NaCl + CO 2 + H 2 O 2H + + CO 3 2– ® CO 2 + H 2 O .
Сa Cl 2 + H 2 SO 4 ® CaSO 4 ¯ + 2HCl Сa 2+ + SO 4 2- ® CaSO 4 ¯.
Under the action of acids, basic salts transform into intermediate salts:
FeOHCl + HCl ® FeCl 2 + H 2 O.
Medium salts formed by polybasic acids, when interacting with them, form acid salts:
Na 2 SO 4 + H 2 SO 4 ® 2NaHSO 4 .
5) Interaction with alkalis. Salts whose cations correspond to insoluble bases react with alkalis. .
CuSO 4 + 2NaOH ® Cu(OH) 2 ¯ + Na 2 SO 4 Cu 2+ + 2OH – ® Cu(OH) 2 ¯ .
6) Interaction with each other. A reaction occurs when soluble salts react and a precipitate is formed.
AgNO 3 + NaCl ® AgCl ¯ + NaNO 3 Ag + + Cl – ® AgCl ¯ .
7) Interaction with metals. Each previous metal in a series of stresses displaces the one following it from the solution of its salt:
Fe + CuSO 4 ® Cu ¯ + FeSO 4 Fe + Cu 2+ ® Cu ¯ + Fe 2+ .
Li, Rb , K , Ba , Sr , Ca , Na , Mg , Al , Mn , Zn , Cr , Fe , Cd, Co, Ni, Sn, Pb, H , Sb, Bi, Cu , Hg , Ag , Pd , Pt ,Au
8) Electrolysis (decomposition under the influence of direct electric current). Salts undergo electrolysis in solutions and melts:
2NaCl + 2H2OH2 + 2NaOH + Cl2.
2NaCl melt 2Na + Cl 2.
9) Interaction with acid oxides.
CO 2 + Na 2 SiO 3 ® Na 2 CO 3 + SiO 2
Na 2 CO 3 + SiO 2 CO 2 + Na 2 SiO 3
Receipt. 1) Interaction of metals with non-metals:
2Na + Cl2 ® 2NaCl.
2) Interaction of basic and amphoteric oxides with acidic oxides:
CaO + SiO 2 CaSiO 3 ZnO + SO 3 ZnSO 4.
3) Interaction of basic oxides with amphoteric oxides:
Na 2 O + ZnO Na 2 ZnO 2 .
4) Interaction of metals with acids:
2HCl + Fe ® FeCl 2 + H 2 .
5 ) Interaction of basic and amphoteric oxides with acids:
Na 2 O + 2HNO 3 ® 2NaNO 3 + H 2 O ZnO + H 2 SO 4 ® ZnSO 4 + H 2 O.
6) Interaction of amphoteric oxides and hydroxides with alkalis:
In solution: 2NaOH + ZnO + H 2 O ® Na 2 2OH – + ZnO + H 2 O ® 2–.
When fused with amphoteric oxide: 2NaOH + ZnO Na 2 ZnO 2 + H 2 O.
In solution: 2NaOH + Zn(OH) 2 ® Na 2 2OH – + Zn(OH) 2 ® 2–
For fusion: 2NaOH + Zn(OH) 2 Na 2 ZnO 2 + 2H 2 O.
7) Interaction of metal hydroxides with acids:
Ca(OH) 2 + H 2 SO 4 ® CaSO 4 ¯ + 2H 2 O Zn(OH) 2 + H 2 SO 4 ® ZnSO 4 + 2H 2 O.
8) Interaction of acids with salts:
2HCl + Na 2 S ® 2NaCl + H 2 S .
9) Interaction of salts with alkalis:
Zn S O 4 + 2NaOH ® Na 2 SO 4 + Zn(OH) 2 ¯ .
10) The interaction of salts with each other:
AgNO 3 + KCl ® AgCl ¯ + KNO 3 .
L.A. Yakovishin
In order to answer the question of what salt is, you usually don’t have to think long. This is a chemical compound in Everyday life occurs quite often. There is no need to talk about ordinary table salt. Detailed internal structure salts and their compounds are studied in inorganic chemistry.
Definition of salt
A clear answer to the question of what salt is can be found in the works of M.V. Lomonosov. He assigned this name to fragile bodies that can dissolve in water and do not ignite when exposed to high temperatures or open fire. Later, the definition was derived not from their physical, but from the chemical properties of these substances.
An example of a mixed acid is the calcium salt of hydrochloric and hypochlorous acid: CaOCl 2.
Nomenclature
Salts formed by metals with variable valence have an additional designation: after the formula, the valence is written in Roman numerals in parentheses. Thus, there is iron sulfate FeSO 4 (II) and Fe 2 (SO4) 3 (III). The name of a salt contains the prefix hydro- if it contains unsubstituted hydrogen atoms. For example, potassium hydrogen phosphate has the formula K 2 HPO 4 .
Properties of salts in electrolytes
The theory of electrolytic dissociation gives its own interpretation chemical properties. In light of this theory, salt can be defined as a weak electrolyte which, when dissolved, dissociates (breaks apart) in water. Thus, a salt solution can be represented as a complex of positive negative ions, and the first are not hydrogen atoms H +, and the second are not atoms of the hydroxyl group OH -. There are no ions that are present in all types of salt solutions, so they do not have any common properties. The lower the charges of the ions that form the salt solution, the better they dissociate, the better the electrical conductivity of such a liquid mixture.
Solutions of acid salts
Acidic salts in solution break down into complex negative ions, which are the acid residue, and simple anions, which are positively charged metal particles.
For example, the dissolution reaction of sodium bicarbonate leads to the decomposition of the salt into sodium ions and the remainder HCO 3 -.
The full formula looks like this: NaHCO 3 = Na + + HCO 3 -, HCO 3 - = H + + CO 3 2-.
Solutions of basic salts
Dissociation of basic salts leads to the formation of acid anions and complex cations consisting of metals and hydroxyl groups. These complex cations, in turn, are also capable of breaking down during dissociation. Therefore, in any solution of a salt of the main group, OH - ions are present. For example, the dissociation of hydroxomagnesium chloride proceeds as follows:
Spread of salts
What is salt? This element is one of the most common chemical compounds. Everyone knows table salt, chalk (calcium carbonate) and so on. Among carbonate acid salts, the most common is calcium carbonate. He is integral part marble, limestone, dolomite. Calcium carbonate is also the basis for the formation of pearls and corals. This chemical compound is an integral component for the formation of hard integument in insects and skeletons in chordates.
Table salt has been known to us since childhood. Doctors warn against its excessive use, but in moderation it is essential for vital processes in the body. And it is needed to maintain the correct blood composition and production gastric juice. Saline solutions, an integral part of injections and droppers, are nothing more than a solution of table salt.
Chemical equations
Chemical equation- is an expression of a reaction using chemical formulas. Chemical equations show which substances enter into a chemical reaction and which substances are formed as a result of this reaction. The equation is compiled on the basis of the law of conservation of mass and shows the quantitative relationships of substances participating in a chemical reaction.
As an example, consider the interaction of hydroxide potassium With phosphoric acid :
H 3 PO 4 + 3 KOH = K 3 PO 4 + 3 H 2 O.
From the equation it is clear that 1 mole of orthophosphoric acid (98 g) reacts with 3 moles of potassium hydroxide (3·56 g). As a result of the reaction, 1 mole of potassium phosphate (212 g) and 3 moles of water (3·18 g) are formed.
98 + 168 = 266 g; 212 + 54 = 266 g we see that the mass of substances that entered into the reaction is equal to the mass of the reaction products. The equation of a chemical reaction allows you to make various calculations related to a given reaction.
Complex substances are divided into four classes: oxides, bases, acids and salts.
Oxides - these are complex substances consisting of two elements, one of which is oxygen, i.e. An oxide is a compound of an element with oxygen.
The name of oxides is derived from the name of the element that is part of the oxide. For example, BaO is barium oxide. If the oxide element has a variable valency, then after the name of the element its valence is indicated in parentheses with a Roman numeral. For example, FeO is iron (I) oxide, Fe2O3 is iron (III) oxide.
All oxides are divided into salt-forming and non-salt-forming.
Salt-forming oxides are those oxides that, as a result, chemical reactions form salts. These are oxides of metals and non-metals, which, when interacting with water, form the corresponding acids, and when interacting with bases, the corresponding acidic and normal salts. For example, copper oxide (CuO) is a salt-forming oxide because, for example, when it interacts with hydrochloric acid(HCl) salt is formed:
CuO + 2HCl → CuCl2 + H2O.
As a result of chemical reactions, other salts can be obtained:
CuO + SO3 → CuSO4.
Non-salt-forming oxides are those oxides that do not form salts. Examples include CO, N2O, NO.
Salt-forming oxides are of 3 types: basic (from the word “base”), acidic and amphoteric.
Basic oxides are metal oxides, which correspond to hydroxides, which belong to the class of bases. Basic oxides include, for example, Na2O, K2O, MgO, CaO, etc.
Chemical properties of basic oxides
1. Water-soluble basic oxides react with water to form bases:
Na2O + H2O → 2NaOH.
2. React with acid oxides, forming the corresponding salts
Na2O + SO3 → Na2SO4.
3. React with acids to form salt and water:
CuO + H2SO4 → CuSO4 + H2O.
4. React with amphoteric oxides:
Li2O + Al2O3 → 2LiAlO2.
5. Basic oxides react with acidic oxides, forming salts:
Na2O + SO3 = Na2SO4
If the composition of the oxides contains a non-metal or a metal exhibiting the highest valence (usually from IV to VII) as the second element, then such oxides will be acidic. Acidic oxides (acid anhydrides) are those oxides that correspond to hydroxides belonging to the class of acids. These are, for example, CO2, SO3, P2O5, N2O3, Cl2O5, Mn2O7, etc. Acidic oxides dissolve in water and alkalis, forming salt and water.
Chemical properties of acid oxides
1. React with water to form an acid:
SO3 + H2O → H2SO4.
But not all acidic oxides react directly with water (SiO2, etc.).
2. React with based oxides to form a salt:
CO2 + CaO → CaCO3
3. React with alkalis, forming salt and water:
CO2 + Ba(OH)2 → BaCO3 + H2O.
An amphoteric oxide contains an element that has amphoteric properties. Amphotericity refers to the ability of compounds to exhibit acidic and basic properties depending on conditions. For example, zinc oxide ZnO can be either a base or an acid (Zn(OH)2 and H2ZnO2). Amphotericity is expressed in the fact that, depending on the conditions, amphoteric oxides exhibit either basic or acid properties, for example - Al2O3, Cr2O3, MnO2; Fe2O3 ZnO. For example, the amphoteric nature of zinc oxide manifests itself when it interacts with both hydrochloric acid and sodium hydroxide:
ZnO + 2HCl = ZnCl 2 + H 2 O
ZnO + 2NaOH = Na 2 ZnO 2 + H 2 O
Since not all amphoteric oxides are soluble in water, it is much more difficult to prove the amphoteric nature of such oxides. For example, aluminum (III) oxide exhibits basic properties in the reaction of its fusion with potassium disulfate, and acidic properties when fused with hydroxides:
Al2O3 + 3K2S2O7 = 3K2SO4 + A12(SO4)3
Al2O3 + 2KOH = 2KAlO2 + H2O
For different amphoteric oxides, the duality of properties can be expressed to varying degrees. For example, zinc oxide dissolves equally easily in both acids and alkalis, and iron (III) oxide - Fe2O3 - has predominantly basic properties.
Chemical properties of amphoteric oxides
1. React with acids to form salt and water:
ZnO + 2HCl → ZnCl2 + H2O.
2. React with solid alkalis (during fusion), forming as a result of the reaction salt - sodium zincate and water:
ZnO + 2NaOH → Na2 ZnO2 + H2O.
When zinc oxide interacts with an alkali solution (the same NaOH), another reaction occurs:
ZnO + 2 NaOH + H2O => Na2.
Coordination number is a characteristic that determines the number of nearby particles: atoms or ions in a molecule or crystal. Each amphoteric metal has its own coordination number. For Be and Zn it is 4; For and Al it is 4 or 6; For and Cr it is 6 or (very rarely) 4;
Amphoteric oxides are usually insoluble in water and do not react with it.
Methods for obtaining oxides from simple substances- this is either a direct reaction of the element with oxygen:
or decomposition of complex substances:
a) oxides
4CrO3 = 2Cr2O3 + 3O2-
b) hydroxides
Ca(OH)2 = CaO + H2O
c) acids
H2CO3 = H2O + CO2-
CaCO3 = CaO +CO2
As well as the interaction of acids - oxidizing agents with metals and non-metals:
Cu + 4HNO3 (conc) = Cu(NO3) 2 + 2NO2 + 2H2O
Oxides can be obtained by direct interaction of oxygen with another element, or indirectly (for example, during the decomposition of salts, bases, acids). Under normal conditions, oxides occur in solid, liquid and gaseous state, this type of connection is very common in nature. Oxides are contained in Earth's crust. Rust, sand, water, carbon dioxide are oxides.
Grounds- these are complex substances in the molecules of which metal atoms are connected to one or more hydroxyl groups.
Bases are electrolytes that, when dissociated, form only hydroxide ions as anions.
NaOH = Na + + OH -
Ca(OH)2 = CaOH + + OH - = Ca 2 + + 2OH -
There are several signs of classification of bases:
Depending on their solubility in water, bases are divided into alkalis and insoluble. Alkalies are hydroxides alkali metals(Li, Na, K, Rb, Cs) and alkaline earth metals (Ca, Sr, Ba). All other bases are insoluble.
Depending on the degree of dissociation, bases are divided into strong electrolytes (all alkalis) and weak electrolytes (insoluble bases).
Depending on the number of hydroxyl groups in the molecule, bases are divided into monoacid (1 OH group), for example, sodium hydroxide, potassium hydroxide, diacid (2 OH groups), for example, calcium hydroxide, copper hydroxide (2), and polyacid.
Chemical properties.
OH - ions in solution determine the alkaline environment.
Alkali solutions change the color of indicators:
Phenolphthalein: colorless ® crimson,
Litmus: violet ® blue,
Methyl orange: orange ® yellow.
Alkali solutions react with acidic oxides to form salts of those acids that correspond to the reacting acidic oxides. Depending on the amount of alkali, medium or acidic salts are formed. For example, when calcium hydroxide reacts with carbon(IV) monoxide, calcium carbonate and water are formed:
Ca(OH)2 + CO2 = CaCO3? + H2O
And when calcium hydroxide reacts with excess oxide carbon(IV) calcium bicarbonate is formed:
Ca(OH)2 + CO2 = Ca(HCO3)2
Ca2+ + 2OH- + CO2 = Ca2+ + 2HCO32-
All bases react with acids to form salt and water, for example: when sodium hydroxide reacts with hydrochloric acid, sodium chloride and water are formed:
NaOH + HCl = NaCl + H2O
Na+ + OH- + H+ + Cl- = Na+ + Cl- + H2O
Copper(II) hydroxide dissolves in hydrochloric acid to form copper(II) chloride and water:
Cu(OH)2 + 2HCl = CuCl2 + 2H2O
Cu(OH)2 + 2H+ + 2Cl- = Cu2+ + 2Cl- + 2H2O
Cu(OH)2 + 2H+ = Cu2+ + 2H2O.
The reaction between an acid and a base is called a neutralization reaction.
Insoluble bases, when heated, decompose into water and the metal oxide corresponding to the base, for example:
Cu(OH)2 = CuO + H2 2Fe(OH)3 = Fe2O3 + 3H2O
Alkalis interact with salt solutions if one of the conditions for the ion exchange reaction to proceed to completion is met (a precipitate forms),
2NaOH + CuSO4 = Cu(OH)2? + Na2SO4
2OH- + Cu2+ = Cu(OH)2
The reaction occurs due to the binding of copper cations with hydroxide ions.
When barium hydroxide reacts with a solution of sodium sulfate, a precipitate of barium sulfate is formed.
Ba(OH)2 + Na2SO4 = BaSO4? + 2NaOH
Ba2+ + SO42- = BaSO4
The reaction occurs due to the binding of barium cations and sulfate anions.
Acids - These are complex substances whose molecules include hydrogen atoms that can be replaced or exchanged for metal atoms and an acid residue.
Based on the presence or absence of oxygen in the molecule, acids are divided into oxygen-containing (H2SO4 sulfuric acid, H2SO3 sulfurous acid, HNO3 nitric acid, H3PO4 phosphoric acid, H2CO3 carbonic acid, H2SiO3 silicic acid) and oxygen-free (HF hydrofluoric acid, HCl hydrochloric acid (hydrochloric acid), HBr hydrobromic acid, HI hydroiodic acid, H2S hydrosulfide acid).
Depending on the number of hydrogen atoms in the acid molecule, acids are monobasic (with 1 H atom), dibasic (with 2 H atoms) and tribasic (with 3 H atoms).
ACIDS
The part of an acid molecule without hydrogen is called an acid residue.
Acid residues can consist of one atom (-Cl, -Br, -I) - these are simple acid residues, or they can consist of a group of atoms (-SO3, -PO4, -SiO3) - these are complex residues.
In aqueous solutions, during exchange and substitution reactions, acidic residues are not destroyed:
H2SO4 + CuCl2 → CuSO4 + 2 HCl
Word anhydride means anhydrous, that is, an acid without water. For example,
H2SO4 - H2O → SO3. Anoxic acids do not have anhydrides.
The acid gets its name from the name of the acid-forming element (acid-forming agent) with the addition of the endings “naya” and less often “vaya”: H2SO4 - sulfuric; H2SO3 - coal; H2SiO3 - silicon, etc.
The element can form several oxygen acids. In this case, the indicated endings in the names of acids will be when the element exhibits a higher valence (the acid molecule contains a high content of oxygen atoms). If the element exhibits a lower valence, the ending in the name of the acid will be “empty”: HNO3 - nitric, HNO2 - nitrous.
Acids can be obtained by dissolving anhydrides in water. If anhydrides are insoluble in water, the acid can be obtained by the action of another more strong acid to the salt of the required acid. This method is typical for both oxygen and oxygen-free acids. Oxygen-free acids are also obtained by direct synthesis from hydrogen and a non-metal, followed by dissolving the resulting compound in water:
H2 + Cl2 → 2 HCl;
Solutions of the resulting gaseous substances HCl and H2S are acids.
Under normal conditions, acids exist in both liquid and solid states.
Chemical properties of acids
1. Acid solutions act on indicators. All acids (except silicic) are highly soluble in water. Special substances - indicators allow you to determine the presence of acid.
Indicators are substances of complex structure. They change their color depending on their interaction with different chemicals. In neutral solutions they have one color, in solutions of bases they have another color. When interacting with an acid, they change their color: the methyl orange indicator turns red, and the litmus indicator also turns red.
2. React with bases to form water and a salt, which contains an unchanged acidic residue (neutralization reaction):
H2SO4 + Ca(OH)2 → CaSO4 + 2 H2O.
3. React with base oxides to form water and salt. The salt contains the acid residue of the acid that was used in the neutralization reaction:
H3PO4 + Fe2O3 → 2 FePO4 + 3 H2O.
4. Interact with metals.
For acids to interact with metals, certain conditions must be met:
1. The metal must be sufficiently active with respect to acids (in the series of activity of metals it must be located before hydrogen). The further to the left a metal is in the activity series, the more intensely it interacts with acids;
K, Ca, Na, Mn, Al, Zn, Fe, Ni, Sn, Pb, H2, Cu, Hg, Ag, Au.
But the reaction between a solution of hydrochloric acid and copper is impossible, since copper is in the voltage series after hydrogen.
2. The acid must be strong enough (that is, capable of donating hydrogen ions H+).
When chemical reactions of acid with metals occur, salt is formed and hydrogen is released (except for the interaction of metals with nitric and concentrated sulfuric acids):
Zn + 2HCl → ZnCl2 + H2;
Cu + 4HNO3 → CuNO3 + 2 NO2 + 2 H2O.
However, no matter how different the acids are, they all form hydrogen cations upon dissociation, which determine the series general properties: sour taste, change in color of indicators (litmus and methyl orange), interaction with other substances.
The same reaction occurs between metal oxides and most acids
CuO+ H2SO4 = CuSO4+ H2O
Let's describe the reactions:
2) The second reaction should produce a soluble salt. In many cases, the interaction of the metal with the acid practically does not occur because the resulting salt is insoluble and covers the surface of the metal with a protective film, for example:
Рb + H2SO4 =/ PbSO4 + H2
Insoluble lead(II) sulfate stops the acid from reaching the metal, and the reaction stops just before it begins. For this reason, the majority heavy metals practically does not interact with phosphoric, carbonic and hydrosulfide acids.
3) The third reaction is characteristic of acid solutions, therefore, insoluble acids, such as silicic acid, do not react with metals. A concentrated solution of sulfuric acid and a solution of nitric acid of any concentration interact with metals somewhat differently, therefore the reaction equations between metals and these acids are written in a different way. A dilute solution of sulfuric acid reacts with metals. standing in the voltage series to hydrogen, forming salt and hydrogen.
4) The fourth reaction is a typical ion exchange reaction and occurs only if a precipitate or gas is formed.
Salts - these are complex substances whose molecules consist of metal atoms and acidic residues (sometimes they may contain hydrogen). For example, NaCl is sodium chloride, CaSO4 is calcium sulfate, etc.
Almost all salts are ionic compounds, therefore, ions of acidic residues and metal ions are bound together in salts:
Na+Cl - sodium chloride
Ca2+SO42 - calcium sulfate, etc.
A salt is the product of partial or complete substitution of a metal for the hydrogen atoms of an acid.
Hence, the following types of salts are distinguished:
1. Medium salts - all hydrogen atoms in the acid are replaced by a metal: Na2CO3, KNO3, etc.
2. Acidic salts - not all hydrogen atoms in the acid are replaced by a metal. Of course, acid salts can only form di- or polybasic acids. Monobasic acids cannot produce acid salts: NaHCO3, NaH2PO4, etc. d.
3. Double salts - the hydrogen atoms of a di- or polybasic acid are replaced not by one metal, but by two different ones: NaKCO3, KAl(SO4)2, etc.
4. Basic salts can be considered as products of incomplete, or partial, substitution of hydroxyl groups of bases with acidic residues: Al(OH)SO4, Zn(OH)Cl, etc.
According to international nomenclature, the name of the salt of each acid comes from Latin name element. For example, salts of sulfuric acid are called sulfates: CaSO4 - calcium sulfate, MgSO4 - magnesium sulfate, etc.; salts of hydrochloric acid are called chlorides: NaCl - sodium chloride, ZnCI2 - zinc chloride, etc.
The particle “bi” or “hydro” is added to the name of salts of dibasic acids: Mg(HCl3)2 - magnesium bicarbonate or bicarbonate.
Provided that in a tribasic acid only one hydrogen atom is replaced by a metal, then the prefix “dihydro” is added: NaH2PO4 - sodium dihydrogen phosphate.
Salts are solid substances with very different solubility in water.
The chemical properties of salts are determined by the properties of the cations and anions that comprise them.
1. Some salts decompose when heated:
CaCO3 = CaO + CO2
2. React with acids to form a new salt and a new acid. To carry out this reaction, the acid must be stronger than the salt affected by the acid:
2NaCl + H2SO4 → Na2SO4 + 2HCl.
3. Interact with bases, forming a new salt and a new base:
Ba(OH)2 + MgSO4 → BaSO4↓ + Mg(OH)2.
4. Interact with each other to form new salts:
NaCl + AgNO3 → AgCl + NaNO3.
5. They interact with metals that are in the same range of activity as the metal that is part of the salt.