connections with same degree. sulfur oxidation
indicate the formula of the substance water solution which is called ammonia?
which substance does not react with carbon monoxide (IV)
write the homological difference
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16. Use which reagents to identify hydrochloric and sulfuric acids found in test tubes without labels.a) litmus and water; b) barium chloride and silver nitrate; c) copper (II) hydroxide and litmus.
17. Indicate with what substances amphoteric hydroxides react:
A) HCl, NaOH; b)Mg(OH)2, H2O; c) CaCl2, H2SO4.
18. What will be the environment of the sodium carbonate solution as a result of hydrolysis:
A) sour; b) neutral; c) alkaline.
19. Name the substances that are raw materials for industrial production nitric acid.
A) nitrogen and hydrogen; b) ammonia-air mixture and water; c) air, nitrogen and water.
20. In what case does each of the two diagrams show that nitrogen is an oxidizing agent?
A) N0 – N+2; b) N+5 – N+4; c) N-3 – N0;
N+5 – N0; N0 – N-3; N+5 – N+3.
21. What metals can displace copper from a copper nitrate solution:
A) Hg; b) Zn; c) Ag.
22.About what substance we're talking about, if it is known that with sulfuric acid it forms insoluble in water and in nitric acid the residue acts on phenolphthalein, changing its color to crimson:
A) Ba(OH)2; b) BaCl2; c)Pb(NO3)2
23. How to determine high-quality composition barium chloride? What reagents will be required?
A) sulfuric acid solution and silver nitrate solution; b) alkali solution and sodium sulfate solution;
B) litmus and strong acid.
24. When passing carbon monoxide (IV) through lime water At the beginning, turbidity is observed, then disappears, the solution becomes transparent. Due to what processes are such changes observed?
A) due to the reaction of CO2 with water; b) due to the interaction of CaCO2 sediment with carbon dioxide;
B) due to the transformation of carbonate into bicarbonate. t0
25. Identify substance A using the scheme: CuSO4 + NaOH –––––– ? –––––– A
A) CuO; b) Cu(NO3)2; c) O2
26. What groups of substances can react with NaOH?
A) CO2, CuCl2, HCl; b) SO2, BaSO4, H3PO4; c) Cl2, KCl, H2SO4.
27. Indicate which reaction is qualitative to the ammonium ion NH4+:
A) (NH4)2SO4 + BaCl2 – BaSO4 + 2NH4Cl b) (NH4)2 SO4 + 2KOH – K2SO4 + 2NH3 + 2 H2O
B) (NH4)3PO4 + 3 AgNO3 – Ag3PO4 + 3NH4NO3.
28.Match
Compound Oxidation state of sulfur
1) Na2SO4 A) - 2
3) Fe2(SO3)3 B) +6
29.Formula Name
1) K2SO4 A) nitric acid
2) HNO3 B) calcium oxide
3) CaO B) potassium sulfate
4) Fe(OH)3 D) iron (III) hydroxide
5) H2SO4 D) lead orthophosphate
6) Pb3(PO4)2 E) aluminum chloride
7) AlCl3 G) sulfuric acid
30. Starting substances Reaction products
1) NH3 + HCl - A) K2MnO4 + MnO2 + O2
2) Cu + 2H2SO4(k) - B) 2Al(NO3)3 + 3H2
3) 2KMnO4 - B) NH4Cl
4) BaCl2 + Na2SO4 - D) 2Fe2O3 + 8SO2
5) 4FeS2 + 11O2 - D) CuSO4 + SO2 + 2H2O
6) 2Al + 6HNO3(p) - E) FeO + H2O
H) BaSO4 + 2NaCl
1.Which substance has an ionic bond:A) Oxalic covalent B) hydrogen fluoride C) potassium oxide D) ammonia
2. Find the sum of protons and neutrons in an argon atom which is used for lighting lamps.
A) 6 B) 14 C) 18 D) 12
3. In which substance is the bond ionic?
A) HF B) KF C) F2 D) CO2
4,Highest oxidation state of phosphorus
A)+5 B) +4 C)+6 D)+7
5.Which substance has a hydrogen bond?
A) water B) hydrogen C) diamond D) methane
6. Find the oxidation state of manganese with its compounds: K2MnO4, KmnO4
A)+6:+7 B) +7:+6 C) +2:+4 D)+2:+7
7, Calculate the sum of oxidation states in the following reactions: FeS2+O2-->Fe2O2+SO2
A)24 B)25 C)23 D)11
8, Find the volume of oxygen at i.u. decomposition of 21.7 mercury(II) oxide
A) 2.24 B) 5.01 C) 1.12 D) 2.22
9, Oxidation state of phosphorus in orthophosphoric acid
A)+7 B)+1 C)+2 D)+5
10. Which process does the N^-3-->N^-2 scheme refer to?
A) oxidation b) reduction C) both oxidation and reduction E) decomposition
Please do I will rate it as the best
Alkynes (otherwise acetylene hydrocarbons) are hydrocarbons containing a triple bond between carbon atoms, with general formula CnH2n-2. The carbon atoms at the triple bond are in a state of sp - hybridization.
Reaction of acetylene with bromine water
The acetylene molecule contains a triple bond, bromine breaks it and adds to acetylene. Terabromoethane is formed. Bromine is consumed in the formation of tetrabromoethane. Bromine water (yellow) - discolored.
This reaction proceeds at a lower rate than in the series of ethylene hydrocarbons. The reaction also occurs in stages:
HC ≡ CH + Br 2 → CHBr = CHBr + Br 2 → CHBr 2 - CHBr 2
acetylene → 1,2-dibromoethane → 1,1,2,2-tetrabromoethane
The discoloration of bromine water proves the unsaturation of acetylene.
Reaction of acetylene with potassium permanganate solution
In a solution of potassium permanganate, oxidation of acetylene occurs, and the molecule breaks at the site of the triple bond, and the solution quickly becomes discolored.
3HC ≡ CH + 10KMnO 4 + 2H 2 O → 6CO 2 + 10KOH + 10MnO 2
This reaction is qualitative reaction for double and triple bonds.
Reaction of acetylene with ammonia solution of silver oxide
If acetylene is passed through ammonia solution silver oxide, the hydrogen atoms in the acetylene molecule can easily be replaced by metals, since they have high mobility. IN this experience hydrogen atoms are replaced by silver atoms. Silver acetylenide is formed - a precipitate yellow color(explosive).
CH ≡ CH + OH → AgC≡CAg↓ + NH 3 + H 2 O
This reaction is a qualitative reaction to a triple bond.
DEFINITION
Acetylene (ethyn)- gas is colorless and odorless, has a weak narcotic effect(the structure of the molecule is shown in Fig. 1).
Slightly soluble in water and very soluble in acetone. In the form of an acetone solution, it is stored in steel cylinders filled with some inert porous material. Mixtures of acetylene with air are explosive.
Rice. 1. The structure of the acetylene molecule.
Table 1. Physical properties acetylene.
Acetylene production
There are industrial and laboratory methods obtaining acetylene. Thus, in industry, acetylene is produced by high-temperature cracking of methane:
2CH 4 → CH≡CH +3H 2.
In the laboratory, acetylene is produced by hydrolysis of calcium carbide:
CaC 2 + 2H 2 O = Ca(OH) 2 + C 2 H 2.
In addition to the above reactions, dehydrogenation reactions of alkanes and alkenes are used to produce acetylene:
CH 3 -CH 3 → CH≡CH +2H 2;
CH 2 =CH 2 → CH≡CH +H 2.
Chemical properties of acetylene
Acetylene undergoes addition reactions that occur via the nucleophilic mechanism, such as:
- hydrogenation
СH≡CH +H 2 O→ → CH 3 -CH=O (H 2 SO 4 (18%), t = 90 o C);
- halogenation
СH≡CH +Br 2 →CHBr=CHBr + Br 2 →CHBr 2 -CHBr 2 ;
- hydrohalogenation
СH≡CH + HСl → CH 2 =CHCl + HCl → CH 3 -CHCl 2 .
In addition, acetylene is capable of forming salts when interacting with active metals(1) and silver oxide (2):
2CH≡CH +2Na→2CH≡C-Na + H 2 (1);
СH≡CH + Ag 2 O→ Ag- С≡C-Ag↓ + H 2 O (2).
It is capable of trimerization:
3C 2 H 2 → C 6 H 6 (t = 600 o C, kat = C active).
Application of acetylene
Acetylene is the starting product for many important chemical production. For example, various halogen derivatives are obtained from acetylene, such as tetrachloroethane and trichlorethylene, which are good solvents, as well as vinyl chloride, which serves as a monomer for the production of polyvinyl chloride. In addition, acetylene is used to produce synthetic rubbers.
Examples of problem solving
EXAMPLE 1
| Exercise | An equimolecular mixture of acetylene and formaldehyde reacts completely with 69.6 g of Ag 2 O dissolved in ammonia. Determine the composition of the initial mixture. |
| Solution | Let us write down the equations of the reactions specified in the problem statement: HC≡CH + Ag 2 O → AgC≡Cag + H 2 O (1); H-C(O)H + 2 Ag 2 O → CO 2 + H 2 O + 4Ag (2). Let's calculate the amount of silver oxide substance (I): n(Ag 2 O) = m(Ag 2 O) / M(Ag 2 O); M(Ag 2 O) = 232 g/mol; n(Ag 2 O) = 69.6 / 232 = 0.3 mol. According to equation (2), the amount of formaldehyde substance will be equal to 0.1 mol. According to the conditions of the problem, the mixture is equimolecular, therefore, acetylene will also be 0.1 mol. Let's find the masses of the substances that make up the mixture: M(HC≡CH) = 26 g/mol; M(H-C(O)H) = 30 g/mol; m(HC≡CH) = 0.1 × 26 = 2.6 g; m(H-C(O)H) = 0.1 × 30 = 3 g. |
| Answer | The mass of acetylene is 2.6 g, formaldehyde is 3 g. |
EXAMPLE 2
| Exercise | When passing a mixture of propane and acetylene through a flask with bromine water, the mass of the flask increased by 1.3 g. With complete combustion of the same amount of the initial mixture of hydrocarbons, 14 liters (n.s.) of carbon monoxide (IV) were released. Determine the mass fraction of propane in the initial mixture. |
| Solution | When a mixture of propane and acetylene is passed through a bottle of bromine water, acetylene is absorbed. Let's write the equation chemical reaction corresponding to this process: HC ≡ CH + 2Br 2 → NSVr 2 -SNVr 2. Thus, the value by which the mass of the bottle has increased (1.3 g) represents the mass of acetylene. Let's find the amount of acetylene substance (molar mass - 26 g/mol): n (C 2 H 2) = m (C 2 H 2) / M (C 2 H 2); n (C 2 H 2) = 1.3/26 = 0.05 mol. Let us write the reaction equation for the combustion of acetylene: 2C 2 H 2 + 5O 2 = 4CO 2 + 2H 2 O. According to the reaction equation, 2 moles of acetylene entered it, however, it is known that 0.05 moles of this amount were absorbed by bromine water. Those. stood out: 2-0.05 = 0.1 mol CO 2. Let's find the total amount of carbon monoxide (IV): n sum (CO 2) = V (CO 2) / V m; n sum (CO 2) = 14/22.4 = 0.625 mol. Let's write the equation for the propane combustion reaction: C 3 H 8 + 5 O 2 = 3 CO 2 + 4 H 2 O. Considering that 0.1 mol of carbon monoxide (IV) was released in the combustion reaction of acetylene, the amount of carbon monoxide (IV) released during the combustion of propane is equal to: 0.625 - 0.1 = 0.525 mol CO 2. Let's find the amount of propane that entered into the combustion reaction. According to the reaction equation n(CO 2) : n(C 3 H 8) = 3: 1, i.e. n(C 3 H 8) = n(CO 2) / 3 = 0.525/3 = 0.175 mol. Let's calculate the mass of propane (molar mass 44 g/mol): m(C 3 H 8) = n(C 3 H 8) ×M(C 3 H 8); m(C 3 H 8) = 0.175 × 44 = 7.7 g. Then, total weight mixture of hydrocarbons will be: m mixture = m(C 2 H 2) + m(C 3 H 8) = 1.3 + 7.7 = 9.0 g. Let's find the mass fraction of propane in the mixture: ω = m / m mixture × 100%; ω(C 3 H 8) = m(C 3 H 8) / m mixture × 100%; ω(C 3 H 8) = 7.7/9.0 × 100% = 0.856 × 100% = 85.6%. |
| Answer | Mass fraction propane 85.6%. |
Topic classes on CTP No. 37 Alkiny. Acetylene its structure and properties
Target Form a concept about unsaturated hydrocarbons (alkynes). Introduce students to the structure and properties of alkynes using the example of acetylene
Systematize and generalize knowledge about marginal hydrocarbons and give comparative characteristics alkanes, alkenes and alkynes.
Acetylene and its homologues
Hydrocarbons with the general formula CnH2n-2, the molecules of which have one triple bond, belong to the acetylene series. According to the international nomenclature, hydrocarbons of the acetylene series are called alkynes. Like the hydrocarbons of the ethylene series, the formulas of the hydrocarbons of the acetylene series can be derived from the formulas saturated hydrocarbons. Their names are formed by replacing the suffix -AN with -IN.
The simplest homologues of acetylene
Physical properties
Acetylene gas lighter than air, slightly soluble in water, pure form almost odorless. Changes in the physical properties of hydrocarbons of the acetylene series (as well as alkanes and alkenes) are subject to general patterns: with increasing relative molecular weight The boiling point of substances increases.
Acetylene and its homologues are characterized by addition, oxidation and polymerization reactions.
1. Addition reactions
Hydrocarbons of the acetylene series react with halogens. For example, acetylene discolors bromine water. The addition of bromine occurs in two stages:
At elevated temperatures, acetylene adds hydrogen. Hydrogenation of acetylene also occurs in two stages:
Acetylene also reacts with complex substances. For example, in the presence of mercury(II) sulfate, acetylene adds water, and acetaldehyde (acetic aldehyde) is formed:
If hydrogen chloride is added to acetylene, it forms gaseous substance vinyl chloride, or vinyl chloride:
Vinyl chloride can polymerize:
2.Oxidation reactions
Acetylene decolorizes the potassium permanganate solution.
In air, acetylene burns with a smoky flame.
3. Polymerization reactions
Acetylene can polymerize to benzene:
Receipt
In the laboratory and in industry, acetylene is obtained by reacting calcium carbide with water:
Application
1 For cutting and welding metals;
2 for the production of artificial fibers,
3 dyes,
4 varnishes,
5 perfumes and colognes,
6 medicines,
7 chloroprene rubber,
8 polyvinyl chloride
Questions for self-control
Acetylene is Chemical substance, hydrocarbon, the simplest alkyne having chemical formula C2H2 (C 2 H 2), with a boiling point temperature of -84°C, molar mass 26.04 g/mol. Under atmospheric conditions, acetylene is colorless gas with a density at +20°C and an absolute pressure of 1 bar 1.097 kg/m³ (lighter than air), density at 0°C 1.1716 kg/m³, odorless (a well-known garlic odor is present in acetylene used in industry and non-industrial non-laboratory applications from - for impurities of phosphorus and hydrogen sulfide). Acetylene gas is slightly soluble in water, but easily soluble in acetone and ethyl alcohol.
Acetylene reactions
Acetylene burns in concentrations in air from 2.5% to 80% (and almost up to 100% under certain conditions; at a concentration of 100% and the coincidence of certain conditions, acetylene can violently, explosively, self-decompose into carbon and hydrogen), with the formation of very hot, bright and smoky flame. The combustion temperature of acetylene in air or oxygen can reach 3300°C.
In reactions with metals such as copper, silver and mercury, as well as their alloys and salts, acetylene forms acetylenides. For example, silver nitrate reacts with acetylene to form silver acetylide and nitric acid:
2AgNO 3 + C2H2 → Ag 2 C 2 + 2HNO 3
Some acetylenides, including the aforementioned silver acetylenide Ag2C2, are strong and dangerous explosives that detonate when heated, as well as from impact. There are known cases where silver acetylide formed at the joints of pipes for transporting acetylene, which were soldered with silver solder.
The German chemist Walter Reppe discovered that in the presence of metal catalysts, acetylene can react with many substances, forming industrially significant chemical compounds. These reactions are now called by his name, Reppe reactions.
Reactions of acetylene C2H2 with alcohols ROH, hydrocyanic acid HCN, hydrochloric acid HCl or carboxylic acids give vinyl compounds. For example, acetylene and hydrochloric acid:
C2H2 + HCl →
The reaction of ethylene with carbon monoxide produces acrylic acid or acrylic esters, used in the manufacture of organic glass:
C2H2 + CO + H2O → CH 2 =CHCO 2 H
The cyclization reaction converts acetylene to benzene:
3C2H2 → C6H6
Acetylene production
Basically, acetylene is produced by incomplete combustion of methane or as a by-product and undesirable product of the production of ethylene by cracking hydrocarbons (part of this unwanted acetylene is catalytically hydrogenated into ethylene). Annual acetylene production the last way is approximately 400,000 tons.
Until the 50s of the 20th century, when oil replaced coal as a source of carbon, acetylene was one of the main types of raw materials in chemical industry. Then (and still in laboratory conditions) acetylene was produced by hydrolysis of calcium carbide:
CaC2 + 2H 2 O → Ca(OH) 2 + C2H2
Acetylene cylinders
Acetylene can be liquefied and solidified, but in both the gaseous state at pressures above about 7 bar and in the liquid and solid states, acetylene is shock sensitive and explosive. Therefore, acetylene is always supplied to users in cylinders dissolved in acetone or dimethylformamide and completely filled with a porous filler Agamassan (or AGA-massan, which stands for “AGA composition” in Swedish. AGA is the name of a Swedish manufacturer and supplier of industrial gases , now a division of the Linde Gas company, founded at one time by the inventor of Agamassan, Gustaf Dahlen. Agamassan's composition includes asbestos, cement, coal and kieselguhr). As an alternative to Agamassan, filler based on kieselguhr or ceramics/lime silicate can be used.
In acetylene cylinders it is usually no more than 17 bar, and the outlet pressure from the cylinder is no more than 1 bar, and usually about 0.5 bar.
Acetylene cylinders are usually equipped with both conventional safety valves that operate when the pressure rises, including passing and isothermal, and special safety valves that operate when the temperature rises above 100°C, releasing acetylene into the atmosphere. Such valves act like fusible links.
In Russia, acetylene cylinders are painted in White color, with red inscription "Acetylene".
Use of acetylene
Most famous area The use of acetylene is oxygen-acetylene welding. Oxy-acetylene cutting of metals is also widespread. Both uses are extremely high temperature combustion of acetylene. Approximately 20% of the world's industrially produced acetylene is consumed for these purposes. However, the use of acetylene welding is gradually declining due to the growing popularity of electric arc welding - cutting with oxygen acetylene, however, remains common.
In the chemical industry, acetylene is used in the synthesis of many organic compounds such as acetaldehyde and acetic acid.
Obsolete applications include the use of acetylene as a light source (so-called carbide lamps, in which calcium carbide CaC2 released acetylene when reacted with water and the acetylene was burned, were used, for example, as headlights in all early cars).
Acetylene was previously used as a general anesthetic. At the same time, it can be noted that when handling acetylene you usually should not be particularly afraid of it. physiological effects: before the concentration of acetylene in the inspired air reaches dangerous limits, the lower threshold of flammability will have long been exceeded (remember, this is 2.5%) - which poses a much more serious danger.