| Decision |
4Na + O 2 →2Na 2 O The division of the bases into groups according to various criteria is presented in table 11. Table 11
Base classification All bases except ammonia in water are solids having different colors. For example, calcium hydroxide Ca (OH) 2 white, copper (II) hydroxide Cu (OH) 2 blue, nickel (II) hydroxide Ni (OH) 2 green, iron (III) hydroxide Fe (OH) 3 red- brown, etc. An aqueous solution of ammonia NH 3 H 2 O, unlike other bases, does not contain metal cations, but a complex singly charged ammonium cation NH - 4 and exists only in solution (this solution is known to you as ammonia). It easily decomposes into ammonia and water: However, no matter how different the bases are, they all consist of metal ions and hydroxo groups, the number of which is equal to the oxidation state of the metal. All bases, and primarily alkalis (strong electrolytes), form hydroxide ions OH - during dissociation, which determine a number of common properties: soapiness to the touch, discoloration of indicators (litmus, methyl orange and phenolphthalein), interaction with other substances. Typical reactions grounds The first reaction (universal) was considered in § 38. Laboratory experiment No. 23
The interaction of alkalis with acids
Write down two molecular equations reactions, the essence of which is expressed by the following ionic equation: H + + OH - \u003d H 2 O. Carry out the reactions, the equations of which you have made. Remember what substances (except acids and alkalis) are needed to observe these chemical reactions.
The second reaction takes place between alkalis and non-metal oxides, which correspond to acids, for example, Corresponds When oxides interact with bases, salts of the corresponding acids and water are formed: Rice. 141.
The interaction of alkali with non-metal oxide Laboratory experiment No. 24
Interaction of alkalis with oxides of non-metals
Repeat the experiment you did before. Pour 2-3 ml of a clear solution of lime water into a test tube. Place a juice straw in it, which acts as a gas outlet tube. Gently pass exhaled air through the solution. What are you watching? Write down the molecular and ionic equations of the reaction. Rice. 142.
The interaction of alkalis with salts:
a - with the formation of a precipitate; b - with the formation of gas The third reaction is a typical ion exchange reaction and only occurs if the result is a precipitate or a gas is released, for example: Laboratory experiment No. 25
The interaction of alkalis with salts
In three tubes, pour 1-2 ml of solutions of substances in pairs: 1st tube - sodium hydroxide and ammonium chloride; 2nd tube - potassium hydroxide and iron sulfate (III); 3rd tube - sodium hydroxide and barium chloride. Heat the contents of the 1st test tube and identify one of the reaction products by smell. Formulate a conclusion about the possibility of interaction of alkalis with salts.
Insoluble bases decompose when heated into metal oxide and water, which is not typical for alkalis, for example: Fe (OH) 2 \u003d FeO + H 2 O. Laboratory experiment No. 26
Preparation and properties of insoluble bases
Pour 1 ml of copper (II) sulfate or chloride solution into two test tubes. Add 3-4 drops of sodium hydroxide solution to each tube. Describe the resulting copper(II) hydroxide. Note. Leave the test tubes with the resulting copper (II) hydroxide for the following experiments. Write the molecular and ionic equations for the reaction. Indicate the type of reaction based on the "number and composition of the starting materials and reaction products". Add 1-2 ml of hydrochloric acid to one of the test tubes with copper (II) hydroxide obtained in the previous experiment. What are you watching? Using a pipette, place 1-2 drops of the resulting solution on a glass or porcelain plate and, using crucible tongs, carefully evaporate it. Examine the crystals that form. Note their color. Write the molecular and ionic equations for the reaction. Indicate the type of reaction on the basis of "the number and composition of the starting materials and reaction products", "participation of a catalyst" and "reversibility of a chemical reaction". Heat one of the test tubes with copper hydroxide obtained earlier or given by the teacher () (Fig. 143). What are you watching? Rice. 143.
Decomposition of copper (II) hydroxide when heated Make an equation for the reaction, indicate the condition of its occurrence and the type of reaction according to the signs "the number and composition of the starting materials and reaction products", "release or absorption of heat" and "reversibility of the chemical reaction". Keywords and phrases - Base classification.
- Typical properties of bases: their interaction with acids, non-metal oxides, salts.
- Typical property of insoluble bases: decomposition when heated.
- Conditions for typical base reactions.
Work with computer - Refer to the electronic application. Study the material of the lesson and complete the suggested tasks.
- Search the Internet for email addresses that can serve as additional sources that reveal the content of the keywords and phrases of the paragraph. Offer the teacher your help in preparing a new lesson - make a message on keywords and phrases in the next paragraph.
1. Metal + Non-metal.
Inert gases do not enter into this interaction. The higher the electronegativity of a nonmetal, the more a large number metals it will react. For example, fluorine reacts with all metals, and hydrogen only with active ones. The further to the left a metal is in the activity series of metals, the more non-metals 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 non-metal acts as an oxidizing agent, less EO - as a reducing agent. Non-metals with similar electronegativity do not interact well 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 under harsh conditions can react with fluorine.
Oxygen does not interact with chlorine, bromine and iodine. Oxygen can react with fluorine at low temperatures.
3. Metal + acid oxide.
Metal restores non-metal from oxide. The excess metal can then react with the resulting non-metal. For example:
2 Mg + SiO 2 \u003d 2 MgO + Si (for lack of magnesium)
2 Mg + SiO 2 \u003d 2 MgO + Mg 2 Si (with excess magnesium)
4. Metal + acid.
Metals to the left of hydrogen in the voltage series react with acids to release hydrogen.
The exception is acids - oxidizing agents (concentrated sulfuric and any nitric acid), which can react with metals that are in the series of voltages to the right of hydrogen, hydrogen is not released in the reactions, but water and the acid reduction product are obtained.
It is necessary to pay attention to the fact that when a metal interacts with an excess of a polybasic acid, an acid salt can be obtained: Mg +2 H 3 PO 4 \u003d Mg (H 2 PO 4) 2 + H 2.
If the product of the interaction of the acid and the metal is an insoluble salt, then the metal is passivated, since the surface of the metal is protected from the action of the acid by the insoluble salt. For example, the action of dilute sulfuric acid on lead, barium or calcium.
5. Metal + salt. in solution
this reaction involves a metal to the right of magnesium in the voltage series, including magnesium itself, but to the left of the salt metal. If the metal is more active than magnesium, then it does not react with salt, but with water to form alkali, which then reacts with salt. In this case, the initial salt and the resulting salt must be soluble. The insoluble product passivates the metal.
However, there are exceptions to this rule:
2FeCl 3 + Cu \u003d CuCl 2 + 2FeCl 2;
2FeCl 3 + Fe = 3FeCl 2 . Since iron has an intermediate oxidation state, its salt in the highest degree oxidation is easily reduced to a salt in an intermediate oxidation state, oxidizing even less active metals.
in meltsa number of metal stresses do not work. It is possible to determine whether a reaction between a salt and a metal is possible only with the help of 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: 3 Na + AlCl 3 \u003d 3 NaCl + 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, such as aluminum nitrate and iron. Aluminum nitrate decomposes when heated to alumina, 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.
Also, as in molten salts, the possibility of these reactions is determined thermodynamically. Aluminum, magnesium and sodium are often used as reducing agents. For example: 8 Al + 3 Fe 3 O 4 \u003d 4 Al 2 O 3 + 9 Fe exothermic reaction, enthalpy factor);2 Al + 3 Rb 2 O = 6 Rb + Al 2 O 3 (volatile rubidium, enthalpy factor).
8. Non-metal + base.
As a rule, the reaction takes place between a non-metal and an alkali. Not all non-metals can react with alkalis: it must be remembered that halogens enter into this interaction (differently depending on temperature), sulfur (when heated), silicon, phosphorus.
KOH + Cl 2 \u003d KClO + KCl + H 2 O (in the cold)
6 KOH + 3 Cl 2 = KClO 3 + 5 KCl + 3 H 2 O (in hot solution)
6KOH + 3S = K 2 SO 3 + 2K 2 S + 3H 2 O
2KOH + Si + H 2 O \u003d K 2 SiO 3 + 2H 2
3KOH + 4P + 3H 2 O = PH 3 + 3KPH 2 O 2
1) non-metal - reducing agent (hydrogen, carbon):
CO 2 + C \u003d 2CO;
2NO 2 + 4H 2 \u003d 4H 2 O + N 2;
SiO 2 + C \u003d 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 + 2 C \u003d CO 2 + Si C
2) non-metal - oxidizing agent (oxygen, ozone, halogens):
2C O + O 2 \u003d 2CO 2.
WITH O + Cl 2 \u003d CO Cl 2.
2 NO + O 2 \u003d 2 N O 2.
10. Acid oxide + basic oxide
. The reaction proceeds 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, since 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 there is a reverse reaction of decomposition of the base into oxide and water.
12. Basic oxide + acid
. The reaction is possible if the resulting salt exists. If the resulting salt is insoluble, then the reaction may be passivated by blocking the access of the acid to the surface of the oxide. In the case of an excess of a polybasic acid, the formation of an acid salt is possible.
13.
acid oxide + base. As a rule, the reaction goes between alkali and acid oxide. If the acid oxide corresponds to a polybasic acid, an acid salt can be obtained: CO 2 + KOH = KHCO 3 .
Acid oxides corresponding to strong acids can also react with insoluble bases.
Sometimes with insoluble bases oxides corresponding to weak acids react, and an average or basic salt can be obtained (as a rule, less than solute): 2 Mg (OH) 2 + CO 2 \u003d (MgOH) 2 CO 3 + H 2 O.
14.
acid oxide + salt. The reaction can take place in the melt and 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 \u003d Na 2 SiO 3 + CO 2 , in the forward direction, this reaction proceeds in the melt, carbon dioxide is more volatile than silicon oxide; in the opposite direction, the reaction proceeds in solution, carbonic acid is stronger than silicic acid, and silicon oxide precipitates.
It is possible to combine an acid oxide with its own salt, for example, dichromate can be obtained from chromate, and disulfate can be obtained from sulfate, and disulfite can be obtained from sulfite:
Na 2 SO 3 + SO 2 \u003d Na 2 S 2 O 5
To do this, you need to take a crystalline salt and pure oxide, or saturated solution salt and excess acid oxide.
In solution, salts can react with their own acid oxides to form acid salts: Na 2 SO 3 + H 2 O + SO 2 = 2 NaHSO 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 there is a reverse reaction of the decomposition of the acid into oxide and water. For example, sulfuric acid is characterized by the reaction of obtaining 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 back reactions.
16. Base + acid.
The reaction proceeds if at least one of the reactants is soluble. Depending on the ratio of reagents, medium, acidic and basic salts can be obtained.
17. Base + salt.
The reaction proceeds if both starting materials 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, the reaction proceeds if both starting materials are soluble, and at least one non-electrolyte or a 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 iodine can be obtained by the action of orthophosphoric acid on the corresponding salts. You can act with an acid on your own salt to obtain an acid salt, for example: BaSO 4 + H 2 SO 4 \u003d Ba (HSO 4) 2.
19. Salt + salt.As a rule, the reaction proceeds if both starting materials are soluble, and at least one non-electrolyte or a weak electrolyte is obtained as a product.
1) salt does not exist because irreversibly hydrolyzed
. These are the majority of 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 to less soluble basic salts.
Consider examples:
2 FeCl 3 + 3 Na 2 CO 3 = Fe 2
(CO 3
) 3
+ 6 NaCl (1)
Fe 2 (CO 3) 3+ 6H 2 O \u003d 2Fe (OH) 3 + 3 H2CO3
H 2
CO 3
decomposes into water and carbon dioxide, the water in the left and right parts is reduced and it turns out:
Fe 2
(CO 3
) 3
+ 3 H 2 O \u003d 2 Fe (OH) 3 + 3 CO 2
(2)
If we now combine (1) and (2) equations and reduce iron carbonate, we get a total equation reflecting the interaction of iron chloride (III ) and sodium carbonate: 2 FeCl 3 + 3 Na 2 CO 3 + 3 H 2 O \u003d 2 Fe (OH) 3 + 3 CO 2 + 6 NaCl
CuSO 4 + Na 2 CO 3 \u003d CuCO 3
+ Na 2 SO 4 (1)
The underlined salt does not exist due to irreversible hydrolysis:
2CuCO3+ H 2 O \u003d (CuOH) 2 CO 3 + CO 2 (2)
If we now combine (1) and (2) equations and reduce the copper carbonate, we get the total equation reflecting the interaction of sulfate (II ) and sodium carbonate:
2CuSO 4 + 2Na 2 CO 3 + H 2 O \u003d (CuOH) 2 CO 3 + CO 2 + 2Na 2 SO 4
The idea of the modern quantum mechanical model of the atom. Characterization of the state of electrons in an atom using a set of quantum numbers, their interpretation and allowed values
Fill sequence energy levels and sublevels by electrons in multielectron atoms. Pauli principle. Gund's rule. The principle of minimum energy.
Ionization energy and electron affinity energy. The nature of their change by periods and groups periodic system D.I. Mendeleev. Metals and non-metals.
Electronegativity chemical elements. The nature of the change in electronegativity by periods and groups of the periodic system of D.I. Mendeleev. The concept of the degree of oxidation.
Main types chemical bond. covalent bond. The main provisions of the method of valence bonds. General view about the method of molecular orbitals.
Two mechanisms of education covalent bond: conventional and donor-acceptor.
Ionic bond as the limiting case of polarization of a covalent bond. Electrostatic interaction of ions.
11. Metal connections. Metallic bonds as a limiting case of delocalization of valence electron orbitals. Crystal lattices metals.
12. Intermolecular bonds. Van der Waals interactions - dispersive, dipole-dipole, inductive). Hydrogen bond.
13. Main classes inorganic compounds. Oxides of metals and non-metals. The nomenclature of these compounds. Chemical properties basic, acidic and amphoteric oxides.
15. Acids. Anoxic and oxygen acids. Nomenclature (name of acids). Chemical properties of acids.
16. Salts as products of the interaction of acids and bases. Types of salts: medium (normal), acidic, basic, oxosalts, double, complex salts. Salt nomenclature. Chemical properties of salts.
17. Binary compounds of metals and non-metals. The oxidation states of the elements in them. Nomenclature of binary compounds.
18. Types of chemical reactions: simple and complex, homogeneous and heterogeneous, reversible and irreversible.
20. Basic concepts of chemical kinetics. The rate of a chemical reaction. Factors affecting the reaction rate in homogeneous and heterogeneous processes.
22. Effect of temperature on the rate of a chemical reaction. Activation energy.
23. Chemical equilibrium. Equilibrium constant, its dependence on temperature. The possibility of shifting the equilibrium of a chemical reaction. Le Chatelier's principle.
1) Acid is a strong electrolyte.
36. A) Standard hydrogen electrode. oxygen electrode.
37. Nernst equation for calculation of electrode potentials of electrode systems of various types. Nernst equation for hydrogen and oxygen electrodes
3) Metals in the activity series after hydrogen do not react with water.
I - current value
49. Acid-base titration method. Calculations according to the law of equivalents. Titration technique. Volumetric utensils in the titrimetric method
13. Main classes of inorganic compounds. Oxides of metals and non-metals. The nomenclature of these compounds. Chemical properties of basic, acidic and amphoteric oxides.oxides- compounds of an element with oxygen. Oxides that do not form acids, bases and salts under normal conditions are called not salt-forming. Salt-forming oxides are divided into acidic, basic and amphoteric (having dual properties). Non-metals form only acidic oxides, metals - all the rest and some acidic ones. Basic oxides- These are complex chemical substances related to oxides that form salts by chemical reaction with acids or acid oxides and do not react with bases or basic oxides. Properties: 1. Interaction with water: Interaction with water to form a base (or alkali) CaO+H2O = Ca(OH)2 (a well-known lime slaking reaction, which releases a lot of heat!) 2. Interaction with acids: Reaction with acid to form salt and water (solution of salt in water) CaO + H2SO4 \u003d CaSO4 + H2O (Crystals of this substance CaSO4 are known to everyone under the name "gypsum"). 3. Interaction with acid oxides: salt formation CaO + CO2 \u003d CaCO3 (This substance is known to everyone - ordinary chalk!) Acid oxides- these are complex chemicals related to oxides that form salts when chemically interacting with bases or basic oxides and do not interact with acidic oxides. Properties: Chemical reaction with water CO 2 +H 2 O=H 2 CO 3 is a substance - carbonic acid - one of the weak acids, it is added to sparkling water for "bubbles" of gas. Reaction with alkalis (bases): CO 2 +2NaOH=Na 2 CO 3 +H 2 O- soda ash or washing soda. Reaction with basic oxides: CO 2 +MgO=MgCO 3 - resulting salt - magnesium carbonate - also called "bitter salt". Amphoteric oxides- these are complex chemicals, also related to oxides, which form salts upon chemical interaction with both acids (or acid oxides) and bases (or basic oxides). The most common use of the word "amphoteric" in our case refers to metal oxides. Properties: The chemical properties of amphoteric oxides are unique in that they can enter into chemical reactions corresponding to both bases and acids. For example: Reaction with acid oxide: ZnO + H2CO3 \u003d ZnCO3 + H2O - The resulting substance is a solution of "zinc carbonate" salt in water. Reaction with bases: ZnO + 2NaOH = Na2ZnO2 + H2O - the resulting substance is a double salt of sodium and zinc. 14. Bases. Nomenclature of bases. Chemical properties of bases. Amphoteric bases, reactions of their interaction with acids and alkalis.Bases are substances in which metal atoms are bonded to hydroxyl groups. If a substance contains hydroxy groups (OH) that can be cleaved off (like a single "atom") in reactions with other substances, then such a substance is a base. Properties: Interaction with non-metals: under normal conditions, hydroxides do not interact with most non-metals, the exception is the interaction of alkalis with chlorine Interaction with acid oxides to form salts: 2NaOH + SO 2 = Na 2 SO 3 + H 2 O Interaction with acids - neutralization reaction: with the formation of medium salts: 3NaOH + H3PO4 = Na3PO4 + 3H2O education condition medium salt- excess alkali; with the formation of acid salts: NaOH + H3PO4 = NaH2PO4 + H2O the condition for the formation of an acid salt is an excess of acid; with the formation of basic salts: Cu(OH)2 + HCl = Cu(OH)Cl + H2O the condition for the formation of the basic salt is an excess of base. Bases react with salts when a precipitate forms as a result of a reaction, gas evolution, or the formation of a low-dissociating substance. amphoteric called hydroxides, which exhibit both basic and acidic properties, depending on the conditions, i.e. dissolve in acids and alkalis. To all properties of bases, interaction with bases is added.
These are the elements of group I of the periodic system: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr); very soft, ductile, fusible and light, usually silvery white color; chemically very active; react violently with water to form alkalis(whence the name).
 All alkali metals are extremely active, in all chemical reactions exhibit reducing properties, give up their only valence electron, turning into a positively charged cation, exhibit a single oxidation state +1.
The reducing ability increases in the series ––Li–Na–K–Rb–Cs.
All alkali metal compounds are ionic in nature.
Almost all salts are soluble in water.
low melting points,
Small values of density,
Soft, cut with a knife
Due to their activity, alkali metals are stored under a layer of kerosene to block the access of air and moisture. Lithium is very light and floats to the surface in kerosene, so it is stored under a layer of petroleum jelly.
Chemical properties of alkali metals
1. Alkali metals actively interact with water:
2Na + 2H 2 O → 2NaOH + H 2
2Li + 2H 2 O → 2LiOH + H 2
2. Reaction of alkali metals with oxygen:
4Li + O 2 → 2Li 2 O (lithium oxide)
2Na + O 2 → Na 2 O 2 (sodium peroxide)
K + O 2 → KO 2 (potassium superoxide)
In air, alkali metals instantly oxidize. Therefore, they are stored under a layer of organic solvents (kerosene, etc.).
3. In the reactions of alkali metals with other non-metals, binary compounds are formed:
2Li + Cl 2 → 2LiCl (halides)
2Na + S → Na 2 S (sulfides)
2Na + H 2 → 2NaH (hydrides)
6Li + N 2 → 2Li 3 N (nitrides)
2Li + 2C → Li 2 C 2 (carbides)
4. Reaction of alkali metals with acids
(rarely carried out, there is a competing reaction with water):
2Na + 2HCl → 2NaCl + H 2
5. Interaction of alkali metals with ammonia
(sodium amide is formed):
2Li + 2NH 3 = 2LiNH 2 + H 2
6. The interaction of alkali metals with alcohols and phenols, which in this case exhibit acidic properties:
2Na + 2C 2 H 5 OH \u003d 2C 2 H 5 ONa + H 2;
2K + 2C 6 H 5 OH = 2C 6 H 5 OK + H 2 ;
7. Qualitative reaction to alkali metal cations - coloring of the flame in the following colors:
Li + - carmine red
Na + - yellow
K + , Rb + and Cs + - violet
Obtaining alkali metals
Lithium, sodium and potassium metal receive electrolysis of molten salts (chlorides), and rubidium and cesium - reduction in vacuum when their chlorides are heated with calcium: 2CsCl + Ca \u003d 2Cs + CaCl 2
On a small scale, vacuum thermal production of sodium and potassium is also used:
2NaCl + CaC 2 \u003d 2Na + CaCl 2 + 2C;
4KCl + 4CaO + Si \u003d 4K + 2CaCl 2 + Ca 2 SiO 4.
Active alkali metals are released in vacuum thermal processes due to their high volatility (their vapors are removed from the reaction zone).
 Features of the chemical properties of s-elements of group I and their physiological effect
The electronic configuration of the lithium atom is 1s 2 2s 1 . It has the largest atomic radius in the 2nd period, which facilitates the detachment of the valence electron and the emergence of the Li + ion with a stable inert gas (helium) configuration. Therefore, its compounds are formed with the transfer of an electron from lithium to another atom and the occurrence of an ionic bond with a small amount of covalence. Lithium is a typical metallic element. In substance form, it is an alkali metal. It differs from other members of group I in its small size and the smallest, in comparison with them, activity. In this respect, it resembles the group II element, magnesium, located diagonally from Li. In solutions, the Li + ion is highly solvated; it is surrounded by several tens of water molecules. Lithium, in terms of solvation energy - the addition of solvent molecules, is closer to a proton than to alkali metal cations.
The small size of the Li + ion, the high nuclear charge and only two electrons create conditions for the emergence of a rather significant positive charge field around this particle, therefore, in solutions, a significant number of polar solvent molecules are attracted to it and its coordination number is large, the metal is able to form a significant number of organolithium compounds .
Sodium begins the 3rd period, so it has only 1e at the external level - ,
occupying the 3s orbital. The radius of the Na atom is the largest in the 3rd period. These two features determine the nature of the element. Its electronic configuration is 1s 2 2s 2 2p 6 3s 1 .
The only oxidation state of sodium is +1. Its electronegativity is very small, therefore, sodium is present in compounds only in the form of a positively charged ion and gives the chemical bond an ionic character. The size of the Na + ion is much larger than Li +, and its solvation is not so great. However, it does not exist in free form in solution.
The physiological significance of K + and Na + ions is associated with their different adsorbability on the surface of the components that make up earth's crust. Sodium compounds are only slightly adsorbed, while potassium compounds are strongly retained by clay and other substances. Cell membranes, being the cell-environment interface, are permeable to K + ions, as a result of which the intracellular concentration of K + is much higher than that of Na + ions. At the same time, the concentration of Na + in the blood plasma exceeds the content of potassium in it. This circumstance is associated with the emergence of the membrane potential of cells. Ions K + and Na + - one of the main components of the liquid phase of the body. Their ratio with Ca 2+ ions is strictly defined, and its violation leads to pathology. The introduction of Na + ions into the body does not have a noticeable harmful influence. An increase in the content of K + ions is harmful, but under normal conditions, an increase in its concentration never reaches dangerous values. The effect of Rb + , Cs + , Li + ions has not yet been sufficiently studied.
Of the various lesions associated with the use of alkali metal compounds, burns with hydroxide solutions are most common. The action of alkalis is associated with the dissolution of skin proteins in them and the formation of alkaline albuminates. Alkali is released again as a result of their hydrolysis and acts on the deeper layers of the body, causing the appearance of ulcers. Nails under the influence of alkalis become dull and brittle. Eye damage, even with very dilute alkali solutions, is accompanied not only by superficial destruction, but by violations of deeper parts of the eye (iris) and leads to blindness. During the hydrolysis of alkali metal amides, alkali and ammonia are simultaneously formed, causing fibrinous-type tracheobronchitis and pneumonia.
Potassium was obtained by G. Davy almost simultaneously with sodium in 1807 during the electrolysis of wet potassium hydroxide. From the name of this compound - "caustic potash" and the element got its name. The properties of potassium differ markedly from the properties of sodium, due to the difference in the radii of their atoms and ions. In potassium compounds, the bond is more ionic, and in the form of the K + ion, it has a lesser polarizing effect than sodium, due to its large size. The natural mixture consists of three isotopes 39 K, 40 K, 41 K. One of them is 40 K ‑
is radioactive and a certain proportion of the radioactivity of minerals and soil is associated with the presence of this isotope. Its half-life is long - 1.32 billion years. Determining the presence of potassium in a sample is quite easy: vapors of the metal and its compounds turn the flame purple-red. The spectrum of the element is quite simple and proves the presence of 1e - on the 4s orbital. The study of it served as one of the grounds for finding general patterns in the structure of the spectra.
In 1861 Robert Bunsen discovered a new element while studying the salt of mineral springs by spectral analysis. Its presence was proved by dark red lines in the spectrum, which other elements did not give. By the color of these lines, the element was named rubidium (rubidus-dark red). In 1863, R. Bunsen obtained this metal in its pure form by reducing rubidium tartrate (tartar salt) with soot. A feature of the element is the slight excitability of its atoms. Electron emission from it appears under the action of red rays of the visible spectrum. This is due to a small difference in the energies of the atomic 4d and 5s orbitals. Of all the alkaline elements with stable isotopes, rubidium (like cesium) has one of the largest atomic radii and a low ionization potential. Such parameters determine the nature of the element: high electropositivity, extreme chemical activity, low temperature melting (39 0 C) and low resistance to external influences.
The discovery of cesium, like rubidium, is associated with spectral analysis. In 1860, R. Bunsen discovered two bright blue lines in the spectrum that did not belong to any element known at that time. Hence the name "caesius" (caesius), which means sky blue. It is the last element of the alkali metal subgroup still found in measurable amounts. The largest atomic radius and the smallest first ionization potentials determine the nature and behavior of this element. It has a pronounced electropositivity and pronounced metallic qualities. The desire to donate the outer 6s-electron leads to the fact that all its reactions proceed extremely violently. A small difference in the energies of the atomic 5d and 6s orbitals is responsible for the slight excitability of the atoms. Electronic emission in cesium is observed under the action of invisible infrared rays (thermal). This feature of the atomic structure determines the good electrical conductivity of the current. All this makes cesium indispensable in electronic devices. AT recent times more and more attention is paid to cesium plasma as a fuel of the future and in connection with the solution of the problem of thermonuclear fusion.
In air, lithium actively reacts not only with oxygen, but also with nitrogen and is covered with a film consisting of Li 3 N (up to 75%) and Li 2 O. The remaining alkali metals form peroxides (Na 2 O 2) and superoxides (K 2 O 4 or KO 2).
The following substances react with water:
Li 3 N + 3 H 2 O \u003d 3 LiOH + NH 3;
Na 2 O 2 + 2 H 2 O \u003d 2 NaOH + H 2 O 2;
K 2 O 4 + 2 H 2 O \u003d 2 KOH + H 2 O 2 + O 2.
For air regeneration in submarines and spaceships, in insulating gas masks and breathing apparatus combat swimmers (underwater saboteurs) used a mixture of "oxon":
Na 2 O 2 + CO 2 \u003d Na 2 CO 3 + 0.5 O 2;
K 2 O 4 + CO 2 \u003d K 2 CO 3 + 1.5 O 2.
This is currently the standard filling of regenerating cartridges for insulating gas masks for firefighters.
Alkali metals react when heated with hydrogen to form hydrides:
Lithium hydride is used as a strong reducing agent.
Hydroxides alkali metals corrode glass and porcelain dishes, they can not be heated in quartz dishes:
SiO 2 + 2NaOH \u003d Na 2 SiO 3 + H 2 O.
Sodium and potassium hydroxides do not split off water when heated up to their boiling point (more than 1300 0 C). Some sodium compounds are called soda:
a) soda ash, anhydrous soda, laundry soda or just soda - sodium carbonate Na 2 CO 3;
b) crystalline soda - sodium carbonate crystal hydrate Na 2 CO 3. 10H2O;
c) bicarbonate or drinking - sodium bicarbonate NaHCO 3;
d) sodium hydroxide NaOH is called caustic soda or caustic.
We need to know which of the non-metals mentioned in 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 \u003d K 2 SiO 3 + 2H 2,
3S + 6KOH \u003d 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
Need to know what organic matter match the names:
isoprene, divinyl, vinylacetylene, 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=CH 2 is called vinyl!!
At the same time, some inorganic trivial names:
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 SO 3 in concentrated H 2 SO 4), copper sulfate (CuSO 4 ∙5H 2 O).
Some rare reactions
1) Formation of vinylacetylene:
2) Direct oxidation reaction of ethylene to acetaldehyde:
This reaction is insidious in that we know well how acetylene is converted to aldehyde (the Kucherov reaction), and if the ethylene → aldehyde transformation occurs in the chain, then this can confuse us. So, this is the reaction!
3) The reaction of direct oxidation of butane to acetic acid:
This reaction underlies the industrial production of acetic acid.
4) Lebedev's reaction:
Differences between phenols and alcohols
Great amount mistakes in these 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, while phenols react with both alkali and some salts (carbonates, bicarbonates).
For example:
Task 10.1
Which of these substances react with lithium:
a) ethylene glycol, b) methanol, c) phenol, d) cumene, e) glycerin.
Task 10.2
Which of these substances react with potassium hydroxide:
a) ethylene glycol, b) styrene, c) phenol, d) ethanol, e) glycerin.
Task 10.3
Which of these substances react with cesium bicarbonate:
a) ethylene glycol, b) toluene, c) propanol-1, d) phenol, e) glycerin.
2) It should be remembered that alcohols react with hydrogen halides (this reaction proceeds via the C-O bond), but not phenols (the C-O bond in them is inactive due to the conjugation effect).
disaccharides
Main disaccharides: sucrose, lactose and maltose have the same formula C 12 H 22 O 11 .
They should be remembered:
1) that they are able to hydrolyze into those monosaccharides that make up: 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 reactions of “silver” and “copper” mirrors), and sucrose, a non-reducing disaccharide, does not have an aldehyde function.
Reaction mechanisms
Let's hope that the following knowledge is enough:
1) for alkanes (including in the side chains of arenes, if these chains are limiting), reactions are characteristic free radical substitution
(with halogens) that go along radical mechanism
(chain initiation - the formation of free radicals, the development of the chain, chain termination on the walls of the vessel or during the collision of radicals);
2) reactions are characteristic for alkenes, alkynes, arenes electrophilic addition
that go along ionic mechanism
(through 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 able to enter into addition reaction
with hydrogen. But only benzene can also enter into addition reaction
with chlorine (only benzene and only with 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 in one of its types is almost certain to occur!
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 by 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 by the reaction of aluminum with alkali:
C 6 H 5 NO 2 + 2Al + 2NaOH + 4H 2 O → C 6 H 5 NH 2 + 2Na
Amine properties
For some reason, the properties of amines are the least remembered. Perhaps this is due to the fact that amines are studied in the course organic chemistry the latter, and their properties cannot be repeated by studying other classes of substances. Therefore, the recipe is this: just learn all the properties of amines, amino acids and proteins.
|
Salt19 Salt
1. Metal + Non-metal. Inert gases do not enter into this interaction. The higher the electronegativity of a non-metal, the more metals it will react with. For example, fluorine reacts with all metals, and hydrogen only with active ones. The further to the left a metal is in the activity series of metals, the more non-metals 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 non-metal acts as an oxidizing agent, less EO - as a reducing agent. Non-metals with similar electronegativity do not interact well 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 under harsh conditions can react with fluorine. Oxygen does not interact with chlorine, bromine and iodine. Oxygen can react with fluorine at low temperatures.
3. Metal + acid oxide. Metal restores non-metal from oxide. The excess metal can then react with the resulting non-metal. For example:
2Mg + SiO 2 \u003d 2MgO + Si (with a lack of magnesium)
2Mg + SiO 2 \u003d 2MgO + Mg 2 Si (with an excess of magnesium)
4. Metal + acid. Metals to the left of hydrogen in the voltage series react with acids to release hydrogen.
The exception is acids - oxidizing agents (concentrated sulfuric and any nitric acid), which can react with metals that are in the series of voltages to the right of hydrogen, hydrogen is not released in the reactions, but water and the acid reduction product are obtained.
It is necessary to pay attention to the fact that when a metal interacts with an excess of a polybasic acid, an acid salt can be obtained: Mg + 2H 3 PO 4 \u003d Mg (H 2 PO 4) 2 + H 2.
If the product of the interaction of the acid and the metal is an insoluble salt, then the metal is passivated, since the surface of the metal is protected from the action of the acid by the insoluble salt. For example, the action of dilute sulfuric acid on lead, barium or calcium.
5. Metal + salt. in solution this reaction involves a metal to the right of magnesium in the voltage series, including magnesium itself, but to the left of the salt metal. If the metal is more active than magnesium, then it does not react with salt, but with water to form alkali, which then reacts with salt. In this case, the initial salt and the resulting salt must be soluble. The insoluble product passivates the metal.
However, there are exceptions to this rule:
2FeCl 3 + Cu \u003d 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 an intermediate oxidation state, oxidizing even less active metals.
in melts a number of metal stresses do not work. It is possible to determine whether a reaction between a salt and a metal is possible only with the help of 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, such as 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. Also, 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. Two options are possible 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 takes place between a non-metal and an alkali. Not all non-metals can react with alkalis: it must be remembered that halogens enter into this interaction (differently depending on temperature), sulfur (when heated), silicon, phosphorus.
2KOH + Cl 2 \u003d 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 \u003d 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 \u003d 2CO;
2NO 2 + 4H 2 \u003d 4H 2 O + N 2;
SiO 2 + C \u003d 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 \u003d 2CO 2.
CO + Cl 2 \u003d COCl 2.
2NO + O 2 \u003d 2NO 2.
10. Acid oxide + basic oxide. The reaction proceeds 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, since 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 there is a reverse reaction of decomposition of the base into oxide and water.
12. Basic oxide + acid. The reaction is possible if the resulting salt exists. If the resulting salt is insoluble, then the reaction may be passivated by blocking the access of the acid to the surface of the oxide. In the case of an excess of a polybasic acid, the formation of an acid salt is possible.
13. Acid oxide + base. As a rule, the reaction goes between alkali and acid oxide. If the acid oxide corresponds to a polybasic acid, an acid salt can be obtained: CO 2 + KOH \u003d KHCO 3.
Acid oxides corresponding to strong acids can also react with insoluble bases.
Sometimes oxides corresponding to weak acids react with insoluble bases, and an average or basic salt can be obtained (as a rule, a less soluble substance is obtained): 2Mg (OH) 2 + CO 2 \u003d (MgOH) 2 CO 3 + H 2 O.
14. Acid oxide + salt. The reaction can take place in the melt and 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 \u003d Na 2 SiO 3 + CO 2, in the forward direction this reaction proceeds in the melt, carbon dioxide is more volatile than silicon oxide; in the opposite direction, the reaction proceeds in solution, carbonic acid is stronger than silicic acid, and silicon oxide precipitates.
It is possible to combine an acid oxide with its own salt, for example, dichromate can be obtained from chromate, and disulfate can be obtained from sulfate, and disulfite can be obtained from sulfite:
Na 2 SO 3 + SO 2 \u003d 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 there is a reverse reaction of the decomposition of the acid into oxide and water. For example, sulfuric acid is characterized by the reaction of obtaining 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 back reactions.
16. Base + acid. The reaction proceeds if at least one of the reactants is soluble. Depending on the ratio of reagents, medium, acidic and basic salts can be obtained.
17. Base + salt. The reaction proceeds if both starting materials 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, the reaction proceeds if both starting materials are soluble, and at least one non-electrolyte or a 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 iodine can be obtained by the action of orthophosphoric acid on the corresponding salts. You can act with an acid on your own salt to obtain an acid salt, for example: BaSO 4 + H 2 SO 4 \u003d Ba (HSO 4) 2.
19. Salt + salt. As a rule, the reaction proceeds if both starting materials are soluble, and at least one non-electrolyte or a weak electrolyte is obtained as a product.
Let us pay special attention to those cases when a salt is formed, which is shown by a dash in the solubility table. There are 2 options here:
1) salt does not exist because irreversibly hydrolyzed
. These are the majority of 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 to less soluble basic salts.
Consider examples:
2FeCl 3 + 3Na 2 CO 3 = Fe 2 (CO 3) 3+ 6NaCl (1)
Fe 2 (CO 3) 3+ 6H 2 O \u003d 2Fe (OH) 3 + 3 H2CO3
H2CO3 decomposes into water and carbon dioxide, the water in the left and right parts is reduced and it turns out: Fe 2 (CO 3) 3+ 3H 2 O \u003d 2Fe (OH) 3 + 3 CO2(2)
If we now combine (1) and (2) equations and reduce iron carbonate, we get a total equation that reflects the interaction of iron (III) chloride and sodium carbonate: 2FeCl 3 + 3Na 2 CO 3 + 3H 2 O \u003d 2Fe (OH) 3 + 3CO2 + 6NaCl
CuSO 4 + Na 2 CO 3 \u003d CuCO3+ Na 2 SO 4 (1)
The underlined salt does not exist due to irreversible hydrolysis:
2CuCO3+ H 2 O \u003d (CuOH) 2 CO 3 + CO 2 (2)
If we now combine (1) and (2) equations and reduce copper carbonate, we get a total equation that reflects the interaction of sulfate (II) and sodium carbonate:
2CuSO 4 + 2Na 2 CO 3 + H 2 O \u003d (CuOH) 2 CO 3 + CO 2 + 2Na 2 SO 4
2) Salt does not exist due to intramolecular redox
, such salts include Fe 2 S 3, FeI 3, CuI 2. As soon as they are obtained, they immediately decompose: Fe 2 S 3 \u003d 2FeS + S; 2FeI 3 \u003d 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 record this reaction, if iodide was in short supply, then iodine and iron (II) chloride can be obtained:
2FeCl 3 + 2KI = 2FeCl 2 + I 2 + 2KCl
The proposed scheme does not say anything about amphoteric compounds and their corresponding simple substances. We will pay special attention to them. So, amphoteric oxide in this scheme can take the place of both acidic and basic oxides, amphoteric hydroxide can take the place of acid and base. It must be remembered that, acting as acidic, amphoteric oxides and hydroxides form ordinary salts in an anhydrous medium, 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 \u003d 2Na + 3H 2
EXERCISE
Discuss the possibility of interaction ... This means that you must decide:
1) whether the reaction is possible;
2) if possible, then under what conditions (in solution, in a melt, when heated, etc.), if not possible, then why;
3) whether different products can be obtained under different (what) conditions.
After that, you must write down all possible reactions.
For example: 1. Discuss the possibility of magnesium interacting with potassium nitrate.
1) Reaction possible
2) It can occur in the melt (when heated)
3) In the melt, the reaction is possible, since the nitrate decomposes with the release of oxygen, which oxidizes magnesium.
KNO 3 + Mg = KNO 2 + MgO
2. Discuss the possibility of interaction between sulfuric acid and sodium chloride.
1) Reaction possible
2) It can occur between concentrated acid and crystalline salt
3) Sodium sulfate and sodium hydrosulfate can be obtained as a product (in excess of acid, when heated)
H 2 SO 4 + NaCl \u003d NaHSO 4 + HCl
H 2 SO 4 + 2NaCl \u003d Na 2 SO 4 + 2HCl
Discuss the possibility of a reaction between:
1. Phosphoric 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
Read also:
