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 - sulphuric 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
| Acid Formula | Name of the acid | Salt name | Corresponding oxide |
| HCl | Salt | chlorides | ---- |
| HI | Hydroiodine | iodides | ---- |
| HBr | Hydrobromic | Bromides | ---- |
| HF | Fluoric | Fluorides | ---- |
| HNO3 | Nitrogen | Nitrates | N 2 O 5 |
| H2SO4 | sulfuric | sulfates | SO 3 |
| H2SO3 | sulphurous | Sulfites | SO2 |
| H 2 S | Hydrogen sulfide | Sulfides | ---- |
| H2CO3 | Coal | Carbonates | CO2 |
| H2SiO3 | Silicon | silicates | SiO2 |
| HNO 2 | nitrogenous | Nitrites | N2O3 |
| H3PO4 | Phosphoric | Phosphates | P2O5 |
| H3PO3 | Phosphorous | Phosphites | P2O3 |
| H2CrO4 | Chrome | Chromates | CrO3 |
| H2Cr2O7 | double chrome | bichromates | CrO3 |
| HMnO 4 | manganese | Permanganates | Mn2O7 |
| HClO 4 | Chloric | Perchlorates | Cl2O7 |
Acids in the laboratory can be obtained:
1) when dissolving acid oxides in water:
N 2 O 5 + H 2 O → 2HNO 3;
CrO 3 + H 2 O → H 2 CrO 4;
2) when salts interact with strong acids:
Na 2 SiO 3 + 2HCl → H 2 SiO 3 ¯ + 2NaCl;
Pb(NO 3) 2 + 2HCl → PbCl 2 ¯ + 2HNO 3 .
Acids interact with metals, bases, basic and amphoteric oxides, amphoteric hydroxides and salts:
Zn + 2HCl → ZnCl 2 + H 2;
Cu + 4HNO 3 (concentrated) → Cu(NO 3) 2 + 2NO 2 + 2H 2 O;
H 2 SO 4 + Ca(OH) 2 → CaSO 4 ¯ + 2H 2 O;
2HBr + MgO → MgBr 2 + H 2 O;
6HI + Al 2 O 3 → 2AlBr 3 + 3H 2 O;
H 2 SO 4 + Zn(OH) 2 → ZnSO 4 + 2H 2 O;
AgNO 3 + HCl → AgCl¯ + HNO 3 .
Usually, acids interact only with those metals that are up to hydrogen in the electrochemical series, and free hydrogen is released. With low-active metals (in the electrochemical series, voltages are after hydrogen), such acids do not interact. Acids, which are strong oxidizing agents (nitric, concentrated sulfuric), react with all metals, with the exception of noble ones (gold, platinum), but not hydrogen is released, but water and oxide, for example, SO 2 or NO 2.
A salt is a product of substitution of hydrogen in an acid for a metal.
All salts are divided into:
medium– NaCl, K 2 CO 3 , KMnO 4 , Ca 3 (PO 4) 2 etc.;
sour– NaHCO 3 , KH 2 PO 4 ;
main - CuOHCl, Fe (OH) 2 NO 3.
The average salt is the product of the complete replacement of hydrogen ions in an acid molecule by metal atoms.
Acid salts contain hydrogen atoms that can participate in chemical exchange reactions. In acid salts, incomplete replacement of hydrogen atoms by metal atoms occurred.
Basic salts are the product of incomplete replacement of the hydroxo groups of the bases of polyvalent metals with acidic residues. Basic salts always contain a hydroxo group.
Medium salts are obtained by interaction:
1) acids and bases:
NaOH + HCl → NaCl + H 2 O;
2) acid and basic oxide:
H 2 SO 4 + CaO → CaSO 4 ¯ + H 2 O;
3) acid oxide and base:
SO 2 + 2KOH → K 2 SO 3 + H 2 O;
4) acidic and basic oxides:
MgO + CO 2 → MgCO 3;
5) metal with acid:
Fe + 6HNO 3 (concentrated) → Fe(NO 3) 3 + 3NO 2 + 3H 2 O;
6) two salts:
AgNO 3 + KCl → AgCl¯ + KNO 3 ;
7) salts and acids:
Na 2 SiO 3 + 2HCl → 2NaCl + H 2 SiO 3 ¯;
8) salts and alkalis:
CuSO 4 + 2CsOH → Cu(OH) 2 ¯ + Cs 2 SO 4.
Acid salts are obtained:
1) when neutralizing polybasic acids with alkali in excess acid:
H 3 PO 4 + NaOH → NaH 2 PO 4 + H 2 O;
2) in the interaction of medium salts with acids:
СaCO 3 + H 2 CO 3 → Ca (HCO 3) 2;
3) during the hydrolysis of salts formed by a weak acid:
Na 2 S + H 2 O → NaHS + NaOH.
The main salts are:
1) in the reaction between a base of a multivalent metal and an acid in excess of the base:
Cu(OH) 2 + HCl → CuOHCl + H 2 O;
2) in the interaction of medium salts with alkalis:
СuCl 2 + KOH → CuOHCl + KCl;
3) during the hydrolysis of medium salts formed by weak bases:
AlCl 3 + H 2 O → AlOHCl 2 + HCl.
Salts can interact with acids, alkalis, other salts, with water (hydrolysis reaction):
2H 3 PO 4 + 3Ca(NO 3) 2 → Ca 3 (PO 4) 2 ¯ + 6HNO 3 ;
FeCl 3 + 3NaOH → Fe(OH) 3 ¯ + 3NaCl;
Na 2 S + NiCl 2 → NiS¯ + 2NaCl.
In any case, the ion exchange reaction goes to completion only when a poorly soluble, gaseous, or weakly dissociating compound is formed.
In addition, salts can interact with metals, provided that the metal is more active (has a more negative electrode potential) than the metal that is part of the salt:
Fe + CuSO 4 → FeSO 4 + Cu.
Salts are also characterized by decomposition reactions:
BaCO 3 → BaO + CO 2;
2KClO 3 → 2KCl + 3O 2.
Lab #1
OBTAINING AND PROPERTIES
BASES, ACIDS AND SALT
Experience 1. Obtaining alkalis.
1.1. The interaction of metal with water.
Pour distilled water into a crystallizer or porcelain cup (approximately 1/2 vessel). Get from the teacher a piece of metallic sodium, previously dried with filter paper. Drop a piece of sodium into the crystallizer with water. At the end of the reaction, add a few drops of phenolphthalein. Note the observed phenomena, make an equation for the reaction. Name the resulting compound, write down its structural formula.
1.2. Interaction of metal oxide with water.
Pour distilled water into a test tube (1/3 test tube) and place a lump of CaO into it, mix thoroughly, add 1 - 2 drops of phenolphthalein. Note the observed phenomena, write the reaction equation. Name the resulting compound, give its structural formula.
7. Acids. Salt. Relationship between classes of inorganic substances
7.1. acids
Acids are electrolytes, during the dissociation of which only hydrogen cations H + are formed as positively charged ions (more precisely, hydronium ions H 3 O +).
Another definition: acids are complex substances consisting of a hydrogen atom and acid residues (Table 7.1).
Table 7.1
Formulas and names of some acids, acid residues and salts
| Acid Formula | Name of the acid | Acid residue (anion) | Name of salts (medium) |
|---|---|---|---|
| HF | Hydrofluoric (hydrofluoric) | F- | Fluorides |
| HCl | Hydrochloric (hydrochloric) | Cl- | chlorides |
| HBr | Hydrobromic | Br- | Bromides |
| HI | Hydroiodic | I- | iodides |
| H 2 S | Hydrogen sulfide | S2− | Sulfides |
| H2SO3 | sulphurous | SO 3 2 - | Sulfites |
| H2SO4 | sulfuric | SO 4 2 - | sulfates |
| HNO 2 | nitrogenous | NO 2 - | Nitrites |
| HNO3 | Nitrogen | NO 3 - | Nitrates |
| H2SiO3 | Silicon | SiO 3 2 - | silicates |
| HPO 3 | Metaphosphoric | PO 3 - | Metaphosphates |
| H3PO4 | orthophosphoric | PO 4 3 - | Orthophosphates (phosphates) |
| H4P2O7 | Pyrophosphoric (two-phosphoric) | P 2 O 7 4 - | Pyrophosphates (diphosphates) |
| HMnO 4 | manganese | MnO 4 - | Permanganates |
| H2CrO4 | Chrome | CrO 4 2 - | Chromates |
| H2Cr2O7 | dichrome | Cr 2 O 7 2 - | Dichromates (bichromates) |
| H 2 SeO 4 | Selenic | SeO 4 2 − | selenates |
| H3BO3 | Bornaya | BO 3 3 - | Orthoborates |
| HClO | hypochlorous | ClO- | Hypochlorites |
| HClO 2 | Chloride | ClO 2 - | Chlorites |
| HClO 3 | Chlorine | ClO 3 - | Chlorates |
| HClO 4 | Chloric | ClO 4 - | Perchlorates |
| H2CO3 | Coal | CO 3 3 - | Carbonates |
| CH3COOH | Acetic | CH 3 COO − | Acetates |
| HCOOH | Ant | HCOO- | Formates |
Under normal conditions, acids can be solids (H 3 PO 4 , H 3 BO 3 , H 2 SiO 3 ) and liquids (HNO 3 , H 2 SO 4 , CH 3 COOH). These acids can exist both in individual (100% form) and in the form of dilute and concentrated solutions. For example, H 2 SO 4 , HNO 3 , H 3 PO 4 , CH 3 COOH are known both individually and in solutions.
A number of acids are known only in solutions. These are all hydrohalic (HCl, HBr, HI), hydrogen sulfide H 2 S, hydrocyanic (hydrocyanic HCN), coal H 2 CO 3, sulfurous H 2 SO 3 acid, which are solutions of gases in water. For example, hydrochloric acid is a mixture of HCl and H 2 O, coal is a mixture of CO 2 and H 2 O. It is clear that using the expression "hydrochloric acid solution" is wrong.
Most acids are soluble in water, silicic acid H 2 SiO 3 is insoluble. The vast majority of acids have a molecular structure. Examples of structural formulas of acids:
In most oxygen-containing acid molecules, all hydrogen atoms are bonded to oxygen. But there are exceptions:
Acids are classified according to a number of features (Table 7.2).
Table 7.2
Acid classification
| Classification sign | Acid type | Examples |
|---|---|---|
| The number of hydrogen ions formed during the complete dissociation of an acid molecule | Monobasic | HCl, HNO 3 , CH 3 COOH |
| Dibasic | H 2 SO 4 , H 2 S, H 2 CO 3 | |
| Tribasic | H 3 PO 4 , H 3 AsO 4 | |
| The presence or absence of an oxygen atom in the molecule | Oxygen-containing (acid hydroxides, oxoacids) | HNO 2 , H 2 SiO 3 , H 2 SO 4 |
| Anoxic | HF, H2S, HCN | |
| Degree of dissociation (strength) | Strong (completely dissociate, strong electrolytes) | HCl, HBr, HI, H 2 SO 4 (diff), HNO 3 , HClO 3 , HClO 4 , HMnO 4 , H 2 Cr 2 O 7 |
| Weak (partially dissociate, weak electrolytes) | HF, HNO 2 , H 2 SO 3 , HCOOH, CH 3 COOH, H 2 SiO 3 , H 2 S, HCN, H 3 PO 4 , H 3 PO 3 , HClO, HClO 2 , H 2 CO 3 , H 3 BO 3, H 2 SO 4 (conc) | |
| Oxidizing properties | Oxidizing agents due to H + ions (conditionally non-oxidizing acids) | HCl, HBr, HI, HF, H 2 SO 4 (diff), H 3 PO 4 , CH 3 COOH |
| Oxidizing agents due to the anion (oxidizing acids) | HNO 3, HMnO 4, H 2 SO 4 (conc), H 2 Cr 2 O 7 | |
| Anion Reducing Agents | HCl, HBr, HI, H 2 S (but not HF) | |
| Thermal stability | Exists only in solutions | H 2 CO 3 , H 2 SO 3 , HClO, HClO 2 |
| Easily decomposed when heated | H 2 SO 3 , HNO 3 , H 2 SiO 3 | |
| Thermally stable | H 2 SO 4 (conc), H 3 PO 4 |
All the general chemical properties of acids are due to the presence in their aqueous solutions of an excess of hydrogen cations H + (H 3 O +).
1. Due to an excess of H + ions, aqueous solutions of acids change the color of violet and methyl orange litmus to red (phenolphthalein does not change color, remains colorless). In an aqueous solution of weak carbonic acid, the litmus is not red, but pink; a solution over a precipitate of very weak silicic acid does not change the color of the indicators at all.
2. Acids interact with basic oxides, bases and amphoteric hydroxides, ammonia hydrate (see Ch. 6).
Example 7.1. To carry out the transformation BaO → BaSO 4, you can use: a) SO 2; b) H 2 SO 4; c) Na 2 SO 4; d) SO3.
Solution. The transformation can be carried out using H 2 SO 4:
BaO + H 2 SO 4 \u003d BaSO 4 ↓ + H 2 O
BaO + SO 3 = BaSO 4
Na 2 SO 4 does not react with BaO, and in the reaction of BaO with SO 2 barium sulfite is formed:
BaO + SO 2 = BaSO 3
Answer: 3).
3. Acids react with ammonia and its aqueous solutions to form ammonium salts:
HCl + NH 3 \u003d NH 4 Cl - ammonium chloride;
H 2 SO 4 + 2NH 3 = (NH 4) 2 SO 4 - ammonium sulfate.
4. Non-oxidizing acids with the formation of a salt and the release of hydrogen react with metals located in the row of activity to hydrogen:
H 2 SO 4 (diff) + Fe = FeSO 4 + H 2
2HCl + Zn \u003d ZnCl 2 \u003d H 2
The interaction of oxidizing acids (HNO 3 , H 2 SO 4 (conc)) with metals is very specific and is considered in the study of the chemistry of elements and their compounds.
5. Acids interact with salts. The reaction has a number of features:
a) in most cases, when a stronger acid reacts with a salt of a weaker acid, a salt of a weak acid is formed and a weak acid, or, as they say, a stronger acid displaces a weaker one. The series of decreasing strength of acids looks like this:
Examples of ongoing reactions:
2HCl + Na 2 CO 3 \u003d 2NaCl + H 2 O + CO 2
H 2 CO 3 + Na 2 SiO 3 = Na 2 CO 3 + H 2 SiO 3 ↓
2CH 3 COOH + K 2 CO 3 \u003d 2CH 3 COOK + H 2 O + CO 2
3H 2 SO 4 + 2K 3 PO 4 = 3K 2 SO 4 + 2H 3 PO 4
Do not interact with each other, for example, KCl and H 2 SO 4 (diff), NaNO 3 and H 2 SO 4 (diff), K 2 SO 4 and HCl (HNO 3, HBr, HI), K 3 PO 4 and H 2 CO 3 , CH 3 COOK and H 2 CO 3 ;
b) in some cases, a weaker acid displaces a stronger one from the salt:
CuSO 4 + H 2 S \u003d CuS ↓ + H 2 SO 4
3AgNO 3 (razb) + H 3 PO 4 = Ag 3 PO 4 ↓ + 3HNO 3.
Such reactions are possible when the precipitates of the resulting salts do not dissolve in the resulting dilute strong acids (H 2 SO 4 and HNO 3);
c) in the case of the formation of precipitates that are insoluble in strong acids, a reaction between a strong acid and a salt formed by another strong acid is possible:
BaCl 2 + H 2 SO 4 \u003d BaSO 4 ↓ + 2HCl
Ba(NO 3) 2 + H 2 SO 4 = BaSO 4 ↓ + 2HNO 3
AgNO 3 + HCl = AgCl↓ + HNO 3
Example 7.2. Indicate the series in which the formulas of substances that react with H 2 SO 4 are given (diff).
1) Zn, Al 2 O 3, KCl (p-p); 3) NaNO 3 (p-p), Na 2 S, NaF; 2) Cu (OH) 2, K 2 CO 3, Ag; 4) Na 2 SO 3, Mg, Zn (OH) 2.
Solution. All substances of series 4 interact with H 2 SO 4 (razb):
Na 2 SO 3 + H 2 SO 4 \u003d Na 2 SO 4 + H 2 O + SO 2
Mg + H 2 SO 4 \u003d MgSO 4 + H 2
Zn(OH) 2 + H 2 SO 4 = ZnSO 4 + 2H 2 O
In row 1) the reaction with KCl (p-p) is not feasible, in row 2) - with Ag, in row 3) - with NaNO 3 (p-p).
Answer: 4).
6. Concentrated sulfuric acid behaves very specifically in reactions with salts. It is a non-volatile and thermally stable acid, therefore it displaces all strong acids from solid (!) Salts, since they are more volatile than H 2 SO 4 (conc):
KCl (tv) + H 2 SO 4 (conc) KHSO 4 + HCl
2KCl (tv) + H 2 SO 4 (conc) K 2 SO 4 + 2HCl
Salts formed by strong acids (HBr, HI, HCl, HNO 3, HClO 4) react only with concentrated sulfuric acid and only in the solid state
Example 7.3. Concentrated sulfuric acid, unlike dilute sulfuric acid, reacts:
3) KNO 3 (TV);
Solution. Both acids react with KF, Na 2 CO 3 and Na 3 PO 4, and only H 2 SO 4 (conc) react with KNO 3 (tv).
Answer: 3).
Methods for obtaining acids are very diverse.
Anoxic acids receive:
- by dissolving the corresponding gases in water:
HCl (g) + H 2 O (g) → HCl (p-p)
H 2 S (g) + H 2 O (g) → H 2 S (solution)
- from salts by displacement by stronger or less volatile acids:
FeS + 2HCl \u003d FeCl 2 + H 2 S
KCl (tv) + H 2 SO 4 (conc) = KHSO 4 + HCl
Na 2 SO 3 + H 2 SO 4 Na 2 SO 4 + H 2 SO 3
oxygenated acids receive:
- by dissolving the corresponding acid oxides in water, while the oxidation state of the acid-forming element in the oxide and acid remains the same (NO 2 is an exception):
N 2 O 5 + H 2 O \u003d 2HNO 3
SO 3 + H 2 O \u003d H 2 SO 4
P 2 O 5 + 3H 2 O 2H 3 PO 4
- oxidation of non-metals with oxidizing acids:
S + 6HNO 3 (conc) = H 2 SO 4 + 6NO 2 + 2H 2 O
- by displacing a strong acid from a salt of another strong acid (if a precipitate forms that is insoluble in the resulting acids):
Ba (NO 3) 2 + H 2 SO 4 (razb) \u003d BaSO 4 ↓ + 2HNO 3
AgNO 3 + HCl = AgCl↓ + HNO 3
- displacement of a volatile acid from its salts by a less volatile acid.
For this purpose, non-volatile thermally stable concentrated sulfuric acid is most often used:
NaNO 3 (tv) + H 2 SO 4 (conc) NaHSO 4 + HNO 3
KClO 4 (tv) + H 2 SO 4 (conc) KHSO 4 + HClO 4
- by displacing a weaker acid from its salts with a stronger acid:
Ca 3 (PO 4) 2 + 3H 2 SO 4 = 3CaSO 4 ↓ + 2H 3 PO 4
NaNO 2 + HCl = NaCl + HNO 2
K 2 SiO 3 + 2HBr = 2KBr + H 2 SiO 3 ↓
acids- complex substances consisting of one or more hydrogen atoms capable of being replaced by metal atoms, and acidic 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 |
|
|
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.
Number 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 -
