Substances of molecular and non-molecular structure. Substances of molecular and non-molecular structure What is the structure of carbon monoxide 4
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The molecular structure has
1) silicon oxide (IV)
2) barium nitrate
3) sodium chloride
4) carbon monoxide (II)
Solution.
The structure of a substance is understood from which particles of molecules, ions, atoms its crystal lattice is built. Substances with ionic and metallic bonds have a non-molecular structure. Substances in molecules of which the atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO 2, SiC (carborundum), BN, Fe 3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.
Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of the crystal lattice. Silicon (IV) oxide - covalent bonds, the substance is solid, refractory, the crystal lattice is atomic. Barium nitrate and sodium chloride substances with ionic bonds - the crystal lattice is ionic. Carbon monoxide (II) is a gas in a molecule of covalent bonds, which means that this is the correct answer, the crystal lattice is molecular.
Answer: 4
Source: Demo version of the USE-2012 in chemistry.
In solid form, the molecular structure has
1) silicon oxide (IV)
2) calcium chloride
3) copper (II) sulfate
Solution.
The structure of a substance is understood from which particles of molecules, ions, atoms its crystal lattice is built. Substances with ionic and metallic bonds have a non-molecular structure. Substances in the molecules of which the atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO 2, SiC (carborundum), BN, Fe 3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.
Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of the crystal lattice. Silicon (IV) oxide - covalent bonds, the substance is solid, refractory, the crystal lattice is atomic. Calcium chloride and copper sulfate - substances with ionic bonds - the crystal lattice is ionic. There are covalent bonds in the iodine molecule, and it sublimes easily, which means that this is the correct answer, the crystal lattice is molecular.
Answer: 4
Source: Demo version of the Unified State Exam-2013 in Chemistry.
The ionic crystal lattice has
1) carbon monoxide (II)
3) magnesium bromide
Solution.
Substances with ionic and metallic bonds have a non-molecular structure. Substances in molecules of which the atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.
Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of the crystal lattice.
Magnesium bromide has an ionic crystal lattice.
Tasks A 6 (USE 2013)
Substances of molecular and non-molecular structure. Crystal lattice type. Dependence of the properties of substances on their composition and structure.
The molecular structure has: 1) CO 2 2) KBr 3) MgSO 4 4) SiO 2
Crystal lattice of graphite: 1) ionic 2) molecular 3) atomic 4) metal
The ionic lattice in the crystalline state has: 1) calcium fluoride 2) carbon monoxide (II) 3) phosphorus (V) oxide 4) hydrogen chloride
Are the following judgments about the properties of substances true? A. Substances with molecular lattice have low melting points and low electrical conductivity.
The molecular structure has: 1) silicon oxide (IV) 2) barium nitrate 3) sodium chloride 4) carbon monoxide (II)
The crystal lattice of calcium chloride: 1) ionic 2) molecular 3) metallic 4) atomic
Iodine crystal lattice: 1) metal 2) molecular 3) atomic 4) ionic
Substances with an atomic crystal lattice: 1) very hard and refractory 2) fragile and fusible 3) conduct electric current in solutions 4) conduct electric current in melts
A substance of molecular structure is: 1) sodium chloride 2) graphite 3) carbon monoxide (IV) 4) potassium oxide
A substance of molecular structure is: 1) ozone 2) barium oxide 3) graphite 4) potassium sulfide
The non-molecular structure has: 1) fullerene, 2) diamond, 3) water, 4) carbon dioxide.
The non-molecular structure has: 1) iron, 2) hydrogen, 3) oxygen, 4) carbon monoxide.
The ionic crystal lattice has: 1) potassium bromide, 2) bromine, 3) potassium, 4) hydrogen bromide.
The molecular crystal lattice has: 1) lithium, 2) sodium oxide, 3) red phosphorus, 4) white phosphorus.
The molecular crystal lattice has: 1) sulfur (VI) fluoride, 2) sodium sulfide, 3) graphite, 4) sodium.
The molecular structure has: 1) iodine, 2) potassium iodide, 3) potassium hydroxide, 4) aluminum hydroxide.
The non-molecular structure has: 1) iodine, 2) iodine chloride, 3) potassium hydroxide, 4) acetic acid.
The non-molecular structure has: 1) zinc, 2) formic acid, 3) hydrogen fluoride, 4) oxygen.
The molecular crystal lattice in the solid state has: 1) barium iodide, 2) barium hydroxide, 3) barium, 4) iodine.
The ionic crystal lattice has: 1) fluorine, 2) hydrogen fluoride, 3) sodium hydride, 4) titanium (IV) chloride.
The molecular structure has: 1) silicon oxide (IV), 2) barium nitrate, 3) sodium chloride, 4) carbon monoxide (II).
The molecular crystal lattice are: 1) H 2 O, CuO, 2) CuO, K 2 S, 3) K 2 S, H 2 SO 4, 4) H 2 SO 4, O 2.
The atomic crystal lattice has: 1) graphite, 2) iron, 3) calcium carbonate, 4) nitric acid.
The ionic crystal lattice has: 1) calcium fluoride, 2) silicon oxide, 3) diamond, 4) copper.
A substance that has a low melting point, sublimes when heated, is non-conductive - it has a crystal lattice: 1) ionic, 2) metallic, 3) molecular, 4) atomic.
A solid, fragile substance, the melt of which conducts an electric current - has a crystal lattice: 1) ionic, 2) metallic, 3) molecular, 4) atomic
A substance with high electrical conductivity, malleable, plastic, has a crystal lattice: 1) ionic, 2) metallic, 3) molecular, 4) atomic.
A refractory brittle substance, insoluble in water, has a crystal lattice: 1) ionic, 2) metallic, 3) molecular, 4) atomic
An atom is a structural unit in a crystal lattice: 1) phosphoric acid, 2) white phosphorus, 3) silica, 4) ammonium chloride.
In a tungsten crystal, the particles are bound by a metal bond, therefore tungsten: 1) refractory, 2) chemically resistant, 3) electrically conductive, 4) has a high density.
The ionic type of the crystal lattice is characteristic for: 1) acids, 2) metals, 3) non-metals, 4) salts.
Each of the substances consists of molecules: 1) table salt and oxygen, 2) magnesium oxide and hydrogen chloride, 3) water and chlorine, 4) diamond and soda.
Each of the substances has an atomic crystal lattice: 1) diamond and graphite, 2) ammonia and iodine, 3) ozone and oxygen, 4) water and chalk.
Each of the substances has an ionic crystal lattice: 1) sulfuric acid and carbon monoxide (IV), 2) sodium hydroxide and potassium chloride, 3) calcium carbonate and hydrogen chloride, 4) silicon oxide and copper (II) hydroxide.
Are the following judgments about the types of crystal lattices of substances in the solid state true? A) ethanol has an ionic crystal lattice. B) iodine has a molecular crystal lattice. 1) only A is true, 2) only B is true, 3) both statements are true, 4) both statements are false.
What properties are characteristic of a substance with an atomic crystal lattice? 1) water insolubility and refractoriness, 2) fragility and fusibility, 3) water solubility and volatility, 4) good thermal and electrical conductivity.
In solids of molecular structure, the chemical bond: 1) covalent, 2) metallic, 3) ionic, 4) hydrogen
In solids of atomic structure, the chemical bond between atoms: 1) covalent, 2) metallic, 3) ionic, 4) hydrogen
Some substance is refractory and does not conduct electric current either in solid form or in melt. What crystal lattice does it have? 1) atomic, 2) molecular
Some substance is refractory and does not conduct electric current in solid form, but its aqueous solution is electrically conductive. What crystal lattice does this substance have? 1) atomic, 2) molecular, 3) ionic, 4) metallic.
Select a substance that in the solid state has a molecular crystal lattice: 1) C (graphite), 2) SiO 2, 3) SiC, 4) CO 2
Select a substance that in the solid state has an atomic crystal lattice: 1) SiO 2, 2) SiH 4, 3) O 2, 4) Na.
Select a substance that has an ionic crystal lattice in the solid state: 1) N 2 O 5, 2) HNO 3, 3) NH 4 NO 3, 4) NH 3.
What property is characteristic of substances with an atomic crystal lattice? 1) high density, 2) refractoriness, 3) good solubility in water, 4) electrical conductivity.
The same type of lattice in the crystalline state has: 1) chlorine and hydrogen, 2) water and aluminum, 3) sodium chloride and sulfuric acid, 4) silica and sodium hydroxide.
The smell is possessed by substances with a crystal lattice: 1) atomic, 2) molecular, 3) ionic, 4) metallic.
The molecular lattice in the crystalline state has: 1) sodium chloride, 2) chlorine, 3) sodium, 4) sodium hydroxide.
Chloride ions are absent in crystals: 1) sodium chloride, 2) calcium chloride, 3) phosphorus (V) chloride, 4) cesium chloride.
The ionic crystal lattice in the crystalline state has: 1) bromine, 2) water, 3) sulfuric acid, 4) sodium carbonate.
The metal crystal lattice has: 1) NH 3, 2) AlCl 3, 3) Cu 3 Al, 4) CuO.
Water and have the same type of lattice in the crystalline state: 1) iron, 2) carbon dioxide, 3) table salt, 4) diamond.
The low-melting crystalline substance is readily soluble in ethanol and does not conduct electric current either in the melt or in solution. What crystal lattice does it have? 1) atomic, 2) molecular, 3) ionic, 4) metallic.
Refractory crystalline substance is insoluble in water and conducts heat and electric current well. What crystal lattice does it have? 1) atomic, 2) molecular, 3) ionic, 4) metallic.
The same type of crystal lattice as sodium sulfate has: 1) red phosphorus, 2) hydrogen chloride, 3) sulfuric acid, 4) barium sulfide.
The same type of crystal lattice as sodium has: 1) zinc chloride, 2) sodium sulfate, 3) sodium carbonate, 4) gold.
The same type of crystal lattice as that of oxygen has: 1) bromine, 2) sodium oxide, 3) table salt, 4) potassium.
The same type of lattice in the crystalline state has: 1) fluorine and sodium fluoride, 2) chlorine and potassium chloride, 3) sodium chloride and potassium hydroxide, 4) chlorine (VII) oxide and potassium hydroxide.
Alumina in the crystalline state has the same type of crystal lattice as: 1) aluminum, 2) oxygen, 3) fluorine, 4) aluminum fluoride.
Vanillin is a low-melting crystalline substance with a characteristic odor. What type of crystal lattice does it have? 1) atomic, 2) molecular, 3) ionic, 4) metallic.
The atomic lattice in the crystalline state has: 1) nitrogen, 2) ammonia, 3) silicon carbide, 4) platinum.
The same type of lattice in the crystalline state has: 1) sodium and sodium chloride, 2) barium sulfate and barium, 3) barium sulfate and sulfuric acid, 4) sulfuric acid and sulfur oxide (VI).
Solid substances with a molecular crystal lattice are characterized by high: 1) density, 2) melting point, 3) volatility, 4) bond energy between molecules.
Solid substances with a metal crystal lattice are characterized by low: 1) thermal conductivity, 2) density, 3) volatility at room temperature, 4) electrical conductivity.
Solid substances with an ionic crystal lattice are characterized by low: 1) melting point, 2) bond energy between ions, 3) solubility in water, 4) volatility.
The ionic crystal lattice solid was melted. The resulting liquid: 1) has a high density, 2) evaporates quickly, 3) smells unpleasant, 4) conducts an electric current.
The atomic crystal lattice does not form: 1) silicon, 2) germanium, 3) aluminum, 4) carbon.
If a substance is highly soluble in water, has a high melting point, and is not electrically conductive, then its crystal lattice is: 1) molecular, 2) atomic, 3) ionic, 4) metallic.
The concept of "molecule" is not applicable in relation to the structural unit of a substance: 1) chloroform, 2) oxygen, 3) diamond, 4) ozone.
The atomic crystal lattice is characteristic for: 1) aluminum and aluminum carbide, 2) sulfur and iodine, 3) silicon oxide and sodium chloride, 4) diamond and boron.
Substances with a molecular crystal lattice, as a rule: 1) refractory and readily soluble in water, 2) low-melting and volatile, 3) solid and electrically conductive, 4) heat-conductive and plastic.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| 1 | 3 | 1 | 1 | 4 | 1 | 1 | 3 | 1 | 2 | 1 | 1 | 4 | 1 |
|
| 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 |
| 1 | 3 | 1 | 4 | 3 | 4 | 4 | 1 | 1 | 3 | 1 | 2 | 4 | 3 | 3 |
| 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 44 | 45 |
|
| 4 | 3 | 1 | 2 | 2 | 1 | 4 | 1 | 1 | 3 | 4 | 1 | 3 | 2 | 1 |
| 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 |
| 2 | 2 | 3 | 4 | 3 | 2 | 2 | 4 | 4 | 4 | 1 | 3 | 4 | 2 | 3 |
| 61 | 62 | 63 | 64 | 66 | 67 | 68 | 69 | 70 | ||||||
| 4 | 3 | 3 | 4 | 4 | 3 | 3 | 3 | 4 | 2 |
Substances of molecular and non-molecular structure. Dependence of the properties of substances on the features of their crystal lattice.
1. The molecular structure has
1) C12 2) CaO 3) ZnCl2 4) NaBr
2. The crystal lattice of calcium chloride
1) metal
2) molecular
4) atomic
3. The crystal lattice of solid carbon monoxide (IV)
2) molecular
3) metal
4) atomic
4. The molecular crystal lattice has
1) CaF2 2) CO2 3) SiO2 4) A1F3
5. The non-molecular structure has
1) H2O 2) H2SO4 3) SiO2 4) CO2
6. The molecular structure has
3) silicon
4) table salt
7. The non-molecular structure has
1) nitrogen 2) graphite 3) ammonia 4) oxygen
8. The highest melting point is
1) hydrogen
2) oxygen
3) carbon monoxide (IV)
4) silicon oxide (IV)
9. The ionic structure has
1) boron oxide
2) carbon monoxide (IV)
3) sulfur oxide (VI)
4) magnesium oxide
10. Substances with a metal crystal lattice
1) fragile, low-melting
2) conduct electric current, plastic
3) have low heat and electrical conductivity
4) have good optical properties
11. Each of two substances has a non-molecular structure:
1) CO2 and Cl2 2) Fe and NaCl 3) CO and Mg 4) Na2CO3 and I2 (tv)
12. Substances are solid, durable, with a high melting point, the melts of which conduct electric current, have a crystal lattice
1) metal
2) molecular
3) atomic
13. The molecular crystal lattice has
1) silicon
2) carbon monoxide (IV)
3) silicon oxide
4) ammonium nitrate
14. The molecular crystal lattice is characteristic for each of the substances located in the row:
1) potassium chloride, nitrogen, methane
2) iodine, carbon dioxide, helium
3) aluminum, bromine, diamond
4) hydrogen, magnesium sulfate, iron oxide (III)
15. An ionic crystal lattice has each of the substances located in the row:
1) sodium, sodium chloride, sodium hydride
2) calcium, calcium oxide, calcium carbonate
3) sodium bromide, potassium sulfate, iron (II) chloride
4) magnesium phosphate, potassium chloride, phosphorus (V) oxide
16. The molecular structure has
1) CO2 2) KBr 3) MgS04 4) SiO2
17. Ions are structural particles
1) oxygen
3) carbon monoxide (IV)
4) sodium chloride
18. The metal crystal lattice has
1) malachite
3) silica
19. The crystal lattice of bromine
1) molecular
2) metal
4) atomic
20. Are the following judgments about the dependence of the properties of substances on the features of their crystal lattice true?
A. Melts of substances with an ionic crystal lattice conduct an electric current.
B. Diamond and graphite have an atomic crystal lattice.
1) only A is true
2) only B is true
3) both statements are true
4) both judgments are wrong
21. The non-molecular structure has
22. Ions are a structural unit for each of two substances:
1) СН4 and I2 2) SO, and Н2О 3) Сl2 and NH3 4) LiF and KCl
23. Each of two substances has a molecular structure:
1) NH4C1 and CH3NH3
2) Na2CO3 and HNO3
3) C2H5OH and CH4
4) H2S and CH3COONa
24. The molecular crystal lattice has
1) calcium fluoride
2) aluminum bromide
3) hydrogen sulfide
4) copper (P) chloride
25. The molecular structure has
1) WITH 2H 5ON 2) A1 3) Fe2 (SO4) 3 4) KSU3
26. Substances of only non-molecular structure are listed in the row
1) S8, O2 (g), ice
2) Fe, NaCl (tv), diamond
3) CO2 (g), N2 (g), A1
4) graphite, Na2CO3 (tv), I2
27. The statement that the structural particle of a given substance is a molecule is valid only for
28. The crystal lattice of calcium chloride
29. The crystal lattice of solid carbon (IV) oxide
30. The molecular crystal lattice has
Answers: 1-1, 2-3, 3-2, 4-2, 5-3, 6-2, 7-2, 8-4, 9-4, 10-2, 11-2, 12-1, 13-2, 14-2, 15-3, 16-1, 17-4, 18-2, 19-1, 20-3, 21-3, 22-4, 23-3, 24-3, 25-1, 26-2, 27-4, 28-1, 29-2, 30-2
A5. Substances of molecular and non-molecular structure. Dependence of the properties of substances on the features of their crystal lattice.
1. The molecular structure has
1) Сl 2 2) CaO 3) ZnCl 2 4) NaBr
2. The crystal lattice of calcium chloride
1) metallic 2) molecular 3) ionic 4) atomic
3. The crystal lattice of solid carbon monoxide (IV)
1) ionic 2) molecular 3) metallic 4) atomic
4. The molecular crystal lattice has
1) CaF 2 2) CO 2 3) SiO 2 4) AlF 3
5. The non-molecular structure has
1) H 2 O 2) H 2 SO 4 3) SiO 2 4) CO 2
6. The molecular structure has
1) diamond 2) nitrogen 3) silicon 4) table salt
7. The non-molecular structure has
1) nitrogen 2) graphite 3) ammonia 4) oxygen
8. The highest melting point is
1) hydrogen 2) oxygen 3) carbon monoxide (IV) 4) silicon oxide (IV)
9. The ionic structure has
1) boron oxide 2) carbon oxide (IV) 3) sulfur oxide (VI) 4) magnesium oxide
10. Substances with a metal crystal lattice
1) fragile, low-melting
2) conduct electric current, plastic
3) have low thermal and electrical conductivity
4) have good optical properties
11. Each of two substances has a non-molecular structure:
1) CO 2 and Cl 2 2) Fe and NaCl 3) CO and Mg 4) Na 2 CO 3 and I 2 (tv)
12. Substances are solid, durable, with a high melting point, the melts of which conduct electric current, have a crystal lattice
1) metallic 2) molecular 3) atomic 4) ionic
13. The molecular crystal lattice has
1) silicon 2) carbon monoxide (IV) 3) silicon oxide 4) ammonium nitrate
14. The molecular crystal lattice is characteristic for each of the substances located in the row:
1) potassium chloride, nitrogen, methane
2) iodine, carbon dioxide, helium
3) aluminum, bromine, diamond
4) hydrogen, magnesium sulfate, iron (III) oxide
16. The molecular structure has
1) CO 2 2) KBr 3) MgSO 4 4) SiO 2
17. Ions are structural particles
1) oxygen 2) water 3) carbon monoxide (IV) 4) sodium chloride
18. The metal crystal lattice has
1) malachite 2) bronze 3) silica 4) graphite
19. The crystal lattice of bromine
1) molecular 2) metal 3) ionic 4) atomic
20. Are the following judgments about the dependence of the properties of substances on the features of their crystal lattice true?
A. Melts of substances with an ionic crystal lattice conduct an electric current.
B. Diamond and graphite have an atomic crystal lattice.
1) only A is true 2) only B is true 3) both statements are true 4) both statements are false
21. The non-molecular structure has
1) H 2 O 2) NH 3 3) SiO 2 4) CO 2
22. Ions are a structural unit for each of two substances:
1) CH 4 and I 2 2) SO 2 and H 2 O 3) Cl 2 and NH 3 4) LiF and KCl
23. Each of two substances has a molecular structure:
1) NH 4 Cl and CH 3 NH 3 2) Na 2 CO 3 and HNO 3 3) C 2 H 5 OH and CH 4 4) H 2 S and CH 3 COONa
24. The molecular crystal lattice has
1) calcium fluoride 2) aluminum bromide 3) hydrogen sulfide 4) copper (II) chloride
25. The molecular structure has
1) С 2 Н 5 ОН 2) Аl 3) Fe 2 (SO 4) 3 4) КСlO 3
26. Substances of only non-molecular structure are listed in the row
1) S 8, O 2 (g), ice
2) Fe, NaCl (tv), diamond
3) CO 2 (g), N 2 (g), Al
4) graphite, Na 2 CO 3 (tv), I 2
27. The statement that the structural particle of a given substance is a molecule is valid only for
1) diamond 2) sodium chloride 3) silicon 4) nitrogen
28. The crystal lattice of calcium chloride
29. The crystal lattice of solid carbon (IV) oxide
1) ionic 2) molecular 3) metallic 4) atomic
30. The molecular crystal lattice has
1) CaF 2 2) SO 2 3) SiO 2 4) AlF 3
DEFINITION
Silicon (IV) oxide (silica) is the most stable silicon compound.
It occurs in nature in two states of aggregation - crystalline and amorphous. Crystalline silicon oxide occurs in nature in the form of the mineral quartz, which is a transparent colorless crystals (Fig. 1), in the form of hexagonal prisms with hexagonal pyramids at the ends. Such semi-precious stones as amethyst and topaz are made of quartz.
Silicon oxide (IV) is very hard, insoluble in water and melts at a temperature of the order of 1610 o C turning into a colorless liquid, upon cooling which a transparent glassy mass of amorphous silicon oxide is obtained.
Rice. 1. Silicon oxide (IV). Appearance.
Chemical formula of silicon oxide 4
The chemical formula of silicon oxide (IV) SiO 2. It shows that this molecule contains one silicon atom (Ar = 28 amu) and two oxygen atoms (Ar = 16 amu). The chemical formula can be used to calculate the molecular weight of silica:
Mr (SiO 2) = Ar (Si) + 2 × Ar (O);
Mr (SiO 2) = 28 + 2 × 16 = 28 + 32 = 60.
Graphic (structural) formula of silicon oxide 4
The structural (graphical) formula of silicon oxide (IV) is more illustrative. It shows how atoms are connected to each other inside a molecule:
The structure of the silicon oxide (IV) molecule allows it to form structural links, uniting in chains:
Examples of problem solving
EXAMPLE 1
| Exercise | When 26.7 g of the amino acid (C x H y O z N k) are burned in an excess of oxygen, 39.6 g of carbon monoxide (IV), 18.9 g of water and 4.2 g of nitrogen are formed. Determine the amino acid formula. |
| Solution | Let's draw up a diagram of the combustion reaction of an amino acid, denoting the number of carbon, hydrogen, oxygen and nitrogen atoms for "x", "y", "z" and "k", respectively: C x H y O z N k + O z → CO 2 + H 2 O + N 2. Let us determine the masses of the elements that make up this substance. The values of the relative atomic masses taken from the Periodic Table of D.I. Mendeleev, round up to whole numbers: Ar (C) = 12 amu, Ar (H) = 1 amu, Ar (O) = 16 amu, Ar (N) = 14 amu m (C) = n (C) x M (C) = n (CO 2) x M (C) = x M (C); m (H) = n (H) × M (H) = 2 × n (H 2 O) × M (H) = × M (H); Let's calculate the molar masses of carbon dioxide and water. As you know, the molar mass of a molecule is equal to the sum of the relative atomic masses of the atoms that make up the molecule (M = Mr): M (CO 2) = Ar (C) + 2 × Ar (O) = 12+ 2 × 16 = 12 + 32 = 44 g / mol; M (H 2 O) = 2 × Ar (H) + Ar (O) = 2 × 1 + 16 = 2 + 16 = 18 g / mol. m (C) = x 12 = 10.8 g; m (H) = 2 × 18.9 / 18 × 1 = 2.1 g. m (O) = m (C x H y O z N k) - m (C) - m (H) - m (N) = 26.7 - 10.8 - 2.1 - 4.2 = 9, 6 g Let's define the chemical formula of the amino acid: x: y: z: k = m (C) / Ar (C): m (H) / Ar (H): m (O) / Ar (O): m (N) / Ar (N); x: y: z: k = 10.8 / 12: 2.1 / 1: 9.6 / 16: 4.2 / 14; x: y: z: k = 0.9: 2.1: 0.41: 0.3 = 3: 7: 1.5: 1 = 6: 14: 3: 2. So the simplest formula of the amino acid is C 6 H 14 O 3 N 2. |
| Answer | C 6 H 14 O 3 N 2 |
EXAMPLE 2
| Exercise | Make up the simplest formula of the compound, in which the mass fractions of the elements are approximately equal: carbon - 25.4%, hydrogen - 3.17%, oxygen - 33.86%, chlorine - 37.57%. |
| Solution | The mass fraction of element X in a molecule of composition HX is calculated using the following formula: ω (X) = n × Ar (X) / M (HX) × 100%. Let's denote the number of carbon atoms in a molecule by "x", the number of nitrogen atoms of hydrogen by "y", the number of oxygen atoms by "z" and the number of chlorine atoms by "k". Let us find the corresponding relative atomic masses of the elements carbon, hydrogen, oxygen and chlorine (the values of the relative atomic masses taken from the Periodic Table of D.I.Mendeleev will be rounded to whole numbers). Ar (C) = 12; Ar (H) = 14; Ar (O) = 16; Ar (Cl) = 35.5. We divide the percentage of elements by the corresponding relative atomic masses. Thus, we will find the ratio between the number of atoms in the molecule of the compound: x: y: z: k = ω (C) / Ar (C): ω (H) / Ar (H): ω (O) / Ar (O): ω (Cl) / Ar (Cl); x: y: z: k = 25.4 / 12: 3.17 / 1: 33.86 / 16: 37.57 / 35.5; x: y: z: k = 2.1: 3.17: 2.1: 1.1 = 2: 3: 2: 1. This means that the simplest formula for a compound of carbon, hydrogen, oxygen and chlorine will be C 2 H 3 O 2 Cl. |
| Answer | C 2 H 3 O 2 Cl |
