| Solution |
4Na + O 2 →2Na 2 O We need to know which of the non-metals mentioned in the school course:
C, N 2 , O 2 – do not react with alkalis
Si, S, P, Cl 2, Br 2, I 2, F 2 - react:
Si + 2KOH + H 2 O = K 2 SiO 3 + 2H 2,
3S + 6KOH = 2K 2 S + K 2 SO 3 + 3H 2 O,
Cl 2 + 2KOH (cold) = KCl + KClO + H 2 O,
3Cl 2 + 6KOH (hot) = 5KCl + KClO 3 + 3H 2 O
(similar to bromine and iodine)
4P + 3NaOH + 3H 2 O = 3NaH 2 PO 2 + PH 3
Organic chemistry
Trivial names
You need to know which organic substances correspond to the names:
isoprene, divinyl, vinyl acetylene, toluene, xylene, styrene, cumene, ethylene glycol, glycerin, formaldehyde, acetaldehyde, propionaldehyde, acetone, the first six saturated monobasic acids (formic, acetic, propionic, butyric, valeric, caproic), acrylic acid, stearic acid, palmitic acid, oleic acid, linoleic acid, oxalic acid, benzoic acid, aniline, glycine, alanine. Do not confuse propionic acid with propenoic acid!! Salts of the most important acids: formic - formates, acetic - acetates, propionic - propionates, butyric - butyrates, oxalic - oxalates. The radical –CH=CH2 is called vinyl!!
At the same time, some inorganic trivial names:
Table salt (NaCl), quicklime (CaO), slaked lime (Ca(OH) 2), lime water (Ca(OH) 2 solution), limestone (CaCO 3), quartz (aka silica or silicon dioxide - SiO 2 ), carbon dioxide (CO 2), carbon monoxide (CO), sulfur dioxide (SO 2), brown gas (NO 2), drinking or baking soda (NaHCO 3), soda ash (Na 2 CO 3), ammonia (NH 3), phosphine (PH 3), silane (SiH 4), pyrite (FeS 2), oleum (solution of SO 3 in concentrated H 2 SO 4), copper sulfate (CuSO 4 ∙5H 2 O).
Some rare reactions
1) Formation of vinyl acetylene:
2) Reaction of direct oxidation of ethylene to acetaldehyde:
This reaction is insidious in that we know well how acetylene is converted into aldehyde (Kucherov’s reaction), and if the transformation ethylene → aldehyde occurs in the chain, then this can confuse us. So, this is what this reaction means!
3) Direct oxidation reaction of butane to acetic acid:
This reaction underlies the industrial production of acetic acid.
4) Lebedev's reaction:
Differences between phenols and alcohols
A huge number of errors in such tasks!!
1) It should be remembered that phenols are more acidic than alcohols (the O-H bond in them is more polar). Therefore, alcohols do not react with alkali, but phenols react with alkali and some salts (carbonates, bicarbonates).
For example:
Problem 10.1
Which of these substances react with lithium:
a) ethylene glycol, b) methanol, c) phenol, d) cumene, e) glycerin.
Problem 10.2
Which of these substances react with potassium hydroxide:
a) ethylene glycol, b) styrene, c) phenol, d) ethanol, e) glycerin.
Problem 10.3
Which of these substances react with cesium bicarbonate:
a) ethylene glycol, b) toluene, c) 1-propanol, d) phenol, e) glycerin.
2) It should be remembered that alcohols react with hydrogen halides (this reaction occurs along the C-O bond), but phenols do not (in them the C-O bond is inactive due to the conjugation effect).
Disaccharides
Main disaccharides: sucrose, lactose and maltose have the same formula C 12 H 22 O 11.
These should be remembered:
1) that they are capable of hydrolyzing into those monosaccharides of which they consist: sucrose– for glucose and fructose, lactose– for glucose and galactose, maltose- two glucose.
2) that lactose and maltose have an aldehyde function, that is, they are reducing sugars (in particular, they give “silver” and “copper” mirror reactions), and sucrose is a non-reducing disaccharide and does not have an aldehyde function.
Reaction mechanisms
Let's hope that the following knowledge is sufficient:
1) for alkanes (including in the side chains of arenes, if these chains are limiting) the reactions are characteristic free radical substitution
(with halogens) that come from radical mechanism
(chain initiation - formation of free radicals, chain development, chain termination on the walls of the vessel or upon collision of radicals);
2) alkenes, alkynes, arenes are characterized by reactions electrophilic addition
that go along ionic mechanism
(via Education pi complex
And carbocation
).
Features of benzene
1. Benzene, unlike other arenes, is not oxidized by potassium permanganate.
2. Benzene and its homologues are capable of entering into addition reaction
with hydrogen. But only benzene is also capable of entering into addition reaction
with chlorine (only benzene and only chlorine!). At the same time, all arenas are able to enter into substitution reaction
with halogens.
Zinin's reaction
Reduction of nitrobenzene (or similar compounds) to aniline (or other aromatic amines). This reaction will almost certainly occur in one of its forms!
Option 1 – reduction with molecular hydrogen:
C 6 H 5 NO 2 + 3H 2 → C 6 H 5 NH 2 + 2H 2 O
Option 2 – reduction with hydrogen obtained from the reaction of iron (zinc) with hydrochloric acid:
C 6 H 5 NO 2 + 3Fe + 7HCl → C 6 H 5 NH 3 Cl + 3FeCl 2 + 2H 2 O
Option 3 – reduction with hydrogen obtained from the reaction of aluminum with alkali:
C 6 H 5 NO 2 + 2Al + 2NaOH + 4H 2 O → C 6 H 5 NH 2 + 2Na
Properties of amines
For some reason, the properties of amines are the worst to remember. This may be due to the fact that amines are studied last in organic chemistry courses, and their properties cannot be replicated by studying other classes of substances. Therefore, the recipe is this: just learn all the properties of amines, amino acids and proteins.
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Salt19 Salt
1. Metal + Non-metal. Inert gases do not enter into this interaction. The higher the electronegativity of a nonmetal, the more metals it will react with. For example, fluorine reacts with all metals, and hydrogen reacts only with active ones. The further to the left a metal is in the metal activity series, the more nonmetals it can react with. For example, gold reacts only with fluorine, lithium - with all non-metals.
2. Non-metal + non-metal. In this case, a more electronegative nonmetal acts as an oxidizing agent, and a less electronegative nonmetal acts as a reducing agent. Nonmetals with similar electronegativity interact poorly with each other, for example, the interaction of phosphorus with hydrogen and silicon with hydrogen is practically impossible, since the equilibrium of these reactions is shifted towards the formation of simple substances. Helium, neon and argon do not react with non-metals; other inert gases can react with fluorine under harsh conditions. Oxygen does not interact with chlorine, bromine and iodine. Oxygen can react with fluorine at low temperatures.
3. Metal + acid oxide. The metal reduces the nonmetal from the oxide. The excess metal can then react with the resulting nonmetal. For example:
2Mg + SiO 2 = 2MgO + Si (with magnesium deficiency)
2Mg + SiO 2 = 2MgO + Mg 2 Si (with excess magnesium)
4. Metal + acid. Metals located in the voltage series to the left of hydrogen react with acids to release hydrogen.
The exception is oxidizing acids (concentrated sulfur and any nitric acid), which can react with metals that are in the voltage series to the right of hydrogen; in the reactions, hydrogen is not released, but water and the acid reduction product are obtained.
It is necessary to pay attention to the fact that when a metal reacts with an excess of a polybasic acid, an acid salt can be obtained: Mg + 2H 3 PO 4 = Mg(H 2 PO 4) 2 + H 2.
If the product of the interaction between an acid and a metal is an insoluble salt, then the metal is passivated, since the surface of the metal is protected by the insoluble salt from the action of the acid. For example, the effect of dilute sulfuric acid on lead, barium or calcium.
5. Metal + salt. In solution This reaction involves metals that are in the voltage series to the right of magnesium, including magnesium itself, but to the left of the metal salt. If the metal is more active than magnesium, then it reacts not with salt, but with water to form an alkali, which subsequently reacts with salt. In this case, the original salt and the resulting salt must be soluble. The insoluble product passivates the metal.
However, there are exceptions to this rule:
2FeCl 3 + Cu = CuCl 2 + 2FeCl 2;
2FeCl 3 + Fe = 3FeCl 2. Since iron has an intermediate oxidation state, its salt in the highest oxidation state is easily reduced to a salt in the intermediate oxidation state, oxidizing even less active metals.
In melts a number of metal stresses are not effective. Determining whether a reaction between a salt and a metal is possible can only be done using thermodynamic calculations. For example, sodium can displace potassium from a potassium chloride melt, since potassium is more volatile: Na + KCl = NaCl + K (this reaction is determined by the entropy factor). On the other hand, aluminum was obtained by displacement from sodium chloride: 3Na + AlCl 3 = 3NaCl + Al. This process is exothermic and is determined by the enthalpy factor.
It is possible that the salt decomposes when heated, and the products of its decomposition can react with the metal, for example, aluminum nitrate and iron. Aluminum nitrate decomposes when heated into aluminum oxide, nitric oxide (IV) and oxygen, oxygen and nitric oxide will oxidize iron:
10Fe + 2Al(NO 3) 3 = 5Fe 2 O 3 + Al 2 O 3 + 3N 2
6. Metal + basic oxide. Just as in molten salts, the possibility of these reactions is determined thermodynamically. Aluminum, magnesium and sodium are often used as reducing agents. For example: 8Al + 3Fe 3 O 4 = 4Al 2 O 3 + 9Fe exothermic reaction, enthalpy factor); 2 Al + 3Rb 2 O = 6Rb + Al 2 O 3 (volatile rubidium, enthalpy factor).
7. Non-metal + basic oxide. There are two options here: 1) non-metal – reducing agent (hydrogen, carbon): CuO + H 2 = Cu + H 2 O; 2) non-metal – oxidizing agent (oxygen, ozone, halogens): 4FeO + O 2 = 2Fe 2 O 3.
8. Non-metal + base. As a rule, the reaction occurs between a non-metal and an alkali. Not all non-metals can react with alkalis: you need to remember that halogens (in different ways depending on temperature), sulfur (when heated), silicon, phosphorus enter into this interaction.
2KOH + Cl 2 = KClO + KCl + H 2 O (in the cold)
6KOH + 3Cl 2 = KClO 3 + 5KCl + 3H 2 O (in hot solution)
6KOH + 3S = K 2 SO 3 + 2K 2 S + 3H 2 O
2KOH + Si + H 2 O = K 2 SiO 3 + 2H 2
3KOH + 4P + 3H 2 O = PH 3 + 3KPH 2 O 2
9. Non-metal + acid oxide. There are also two options here:
1) non-metal – reducing agent (hydrogen, carbon):
CO 2 + C = 2CO;
2NO 2 + 4H 2 = 4H 2 O + N 2;
SiO 2 + C = CO 2 + Si. If the resulting non-metal can react with the metal used as a reducing agent, then the reaction will go further (with an excess of carbon) SiO 2 + 2C = CO 2 + SiC
2) non-metal – oxidizing agent (oxygen, ozone, halogens):
2CO + O 2 = 2CO 2.
CO + Cl 2 = COCl 2.
2NO + O 2 = 2NO 2.
10. Acidic oxide + basic oxide. The reaction occurs if the resulting salt exists in principle. For example, aluminum oxide can react with sulfuric anhydride to form aluminum sulfate, but cannot react with carbon dioxide because the corresponding salt does not exist.
11. Water + basic oxide. The reaction is possible if an alkali is formed, that is, a soluble base (or slightly soluble, in the case of calcium). If the base is insoluble or slightly soluble, then the reverse reaction of decomposition of the base into oxide and water occurs.
12. Basic oxide + acid. The reaction is possible if the resulting salt exists. If the resulting salt is insoluble, the reaction may be passivated due to the blocking of acid access to the oxide surface. In case of excess polybasic acid, the formation of an acid salt is possible.
13. Acid oxide + base. Typically, the reaction occurs between an alkali and an acidic oxide. If the acidic oxide corresponds to a polybasic acid, an acidic salt can be obtained: CO 2 + KOH = KHCO 3 .
Acidic oxides, corresponding to strong acids, can also react with insoluble bases.
Sometimes oxides corresponding to weak acids react with insoluble bases, which can result in an average or basic salt (as a rule, a less soluble substance is obtained): 2Mg(OH) 2 + CO 2 = (MgOH) 2 CO 3 + H 2 O.
14. Acid oxide + salt. The reaction can take place in a melt or in solution. In the melt, the less volatile oxide displaces the more volatile oxide from the salt. In solution, the oxide corresponding to the stronger acid displaces the oxide corresponding to the weaker acid. For example, Na 2 CO 3 + SiO 2 = Na 2 SiO 3 + CO 2, in the forward direction this reaction occurs in the melt, carbon dioxide is more volatile than silicon oxide; in the opposite direction, the reaction occurs in solution, carbonic acid is stronger than silicic acid, and silicon oxide precipitates.
It is possible to combine an acidic oxide with its own salt, for example, dichromate can be obtained from chromate, and disulfate from sulfate, and disulfite from sulfite:
Na 2 SO 3 + SO 2 = Na 2 S 2 O 5
To do this, you need to take a crystalline salt and pure oxide, or a saturated salt solution and an excess of acidic oxide.
In solution, salts can react with their own acid oxides to form acid salts: Na 2 SO 3 + H 2 O + SO 2 = 2NaHSO 3
15. Water + acid oxide. The reaction is possible if a soluble or slightly soluble acid is formed. If the acid is insoluble or slightly soluble, then a reverse reaction occurs, the decomposition of the acid into oxide and water. For example, sulfuric acid is characterized by a reaction of production from oxide and water, the decomposition reaction practically does not occur, silicic acid cannot be obtained from water and oxide, but it easily decomposes into these components, but carbonic and sulfurous acids can participate in both direct and reverse reactions.
16. Base + acid. A reaction occurs if at least one of the reactants is soluble. Depending on the ratio of the reagents, medium, acidic and basic salts can be obtained.
17. Base + salt. The reaction occurs if both starting substances are soluble, and at least one non-electrolyte or weak electrolyte (precipitate, gas, water) is obtained as a product.
18. Salt + acid. As a rule, a reaction occurs if both starting substances are soluble, and at least one non-electrolyte or weak electrolyte (precipitate, gas, water) is obtained as a product.
A strong acid can react with insoluble salts of weak acids (carbonates, sulfides, sulfites, nitrites), and a gaseous product is released.
Reactions between concentrated acids and crystalline salts are possible if a more volatile acid is obtained: for example, hydrogen chloride can be obtained by the action of concentrated sulfuric acid on crystalline sodium chloride, hydrogen bromide and hydrogen iodide - by the action of orthophosphoric acid on the corresponding salts. You can act with an acid on your own salt to obtain an acidic salt, for example: BaSO 4 + H 2 SO 4 = Ba(HSO 4) 2.
19. Salt + salt. As a rule, a reaction occurs if both starting substances are soluble, and at least one non-electrolyte or weak electrolyte is obtained as a product.
Let us pay special attention to those cases when a salt is formed, which is shown with a dash in the solubility table. There are 2 options here:
1) salt does not exist because irreversibly hydrolyzes
. These are most carbonates, sulfites, sulfides, silicates of trivalent metals, as well as some salts of divalent metals and ammonium. Trivalent metal salts are hydrolyzed to the corresponding base and acid, and divalent metal salts are hydrolyzed to less soluble basic salts.
Let's look at examples:
2FeCl 3 + 3Na 2 CO 3 = Fe 2 (CO 3) 3+ 6NaCl (1)
Fe 2 (CO 3) 3+ 6H 2 O = 2Fe(OH) 3 + 3 H2CO3
H2CO3 decomposes into water and carbon dioxide, the water in the left and right parts is reduced and the result is: Fe 2 (CO 3) 3+ 3H 2 O = 2Fe(OH) 3 + 3 CO2(2)
If we now combine (1) and (2) equations and reduce iron carbonate, we obtain a summary equation reflecting the interaction of iron (III) chloride and sodium carbonate: 2FeCl 3 + 3Na 2 CO 3 + 3H 2 O = 2Fe(OH) 3 + 3CO2 + 6NaCl
CuSO 4 + Na 2 CO 3 = CuCO3+ Na 2 SO 4 (1)
The underlined salt does not exist due to irreversible hydrolysis:
2CuCO3+ H 2 O = (CuOH) 2 CO 3 +CO 2 (2)
If we now combine (1) and (2) equations and reduce copper carbonate, we obtain a total equation reflecting the interaction of sulfate (II) and sodium carbonate:
2CuSO 4 + 2Na 2 CO 3 + H 2 O = (CuOH) 2 CO 3 + CO 2 + 2Na 2 SO 4
2) Salt does not exist due to intramolecular oxidation-reduction
, such salts include Fe 2 S 3, FeI 3, CuI 2. As soon as they are obtained, they immediately decompose: Fe 2 S 3 = 2FeS+ S; 2FeI 3 = 2FeI 2 +I 2; 2CuI 2 = 2CuI + I 2
For example; FeCl 3 + 3KI = FeI 3 + 3KCl (1),
but instead of FeI 3 you need to write down the products of its decomposition: FeI 2 +I 2.
Then it turns out: 2FeCl 3 + 6KI = 2FeI 2 +I 2 + 6KCl
This is not the only way to write this reaction; if iodide was in short supply, then iodine and iron (II) chloride may be obtained:
2FeCl 3 + 2KI = 2FeCl 2 +I 2 + 2KCl
The proposed scheme says nothing about amphoteric compounds and their corresponding simple substances. We will pay special attention to them. So, an amphoteric oxide in this scheme can take the place of both acidic and basic oxides, and an amphoteric hydroxide can take the place of an acid and a base. It must be remembered that, acting as acidic, amphoteric oxides and hydroxides form ordinary salts in an anhydrous environment, and complex salts in solutions:
Al 2 O 3 + 2NaOH = 2NaAlO 2 + H 2 O (fusion)
Al 2 O 3 + 2NaOH + 3H 2 O = 2Na (in solution)
Simple substances corresponding to amphoteric oxides and hydroxides react with alkali solutions to form complex salts and release hydrogen: 2Al + 2NaOH + 6H 2 O = 2Na + 3H 2
EXERCISE
Discuss the possibility of interaction... This means that you must decide:
1) is a reaction possible;
2) if possible, then under what conditions (in solution, in a melt, when heated, etc.), if not possible, then why;
3) can different products be obtained under different (what) conditions?
After this, you must write down all possible reactions.
For example: 1. discuss the possibility of magnesium interacting with potassium nitrate.
1) Reaction is possible
2) It can occur in a melt (when heated)
3) In the melt, the reaction is possible, since the nitrate decomposes with the release of oxygen, which oxidizes magnesium.
KNO3 + Mg = KNO2 + MgO
2. Discuss the possibility of interaction of sulfuric acid with sodium chloride.
1) Reaction is possible
2) It can occur between concentrated acid and crystalline salt
3) The product can be sodium sulfate and sodium hydrogen sulfate (in excess acid, when heated)
H 2 SO 4 + NaCl = NaHSO 4 + HCl
H 2 SO 4 + 2NaCl = Na 2 SO 4 + 2HCl
Discuss the possibility of a reaction occurring between:
1. Orthophosphoric acid and potassium hydroxide;
2. Zinc oxide and sodium hydroxide;
3. Potassium sulfite and iron (III) sulfate;
4. Copper (II) chloride and potassium iodide;
5. Calcium carbonate and aluminum oxide;
6. Carbon dioxide and sodium carbonate;
7. Iron (III) chloride and hydrogen sulfide;
8. Magnesium and sulfur dioxide;
9. Potassium dichromate and sulfuric acid;
10. Sodium and sulfur.
Let's do a little analysis of examples C2
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