Chemical properties of the elements from VIA group. Lecture 12

Transcription

1 Chemical properties of the elements from VIA group Lecture 12

2 Main topics of the lecture: 1. Natural resources and overall characteristic of elements from VIA group 2. Oxygen and its compounds 3. Sulfur and its compounds 4. The roles of compounds of group VIA elements in medicine and biology

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4 Natural resources of oxygen Oxygen is the most widespread element in the Earth (49.5% per mass). Oxygen exists as: pure chemical element (21% per volume in the air); water; minerals: quartz, carbonates, silicates, alumosilicates and other. Oxygen is an ORGANOGENIC element!!!

5 Natural resources of sulfur Sulfur Pure sulfur Minerals sulfides: Pyrite FeS 2 Halcopyrite CuFeS 2 Sfalerite ZnS Halenite PbS Minerals sulfates: Gypsum CaSO 4 2H 2 O Mirabilite Na 2 SO 4 10H 2 O Pyrite Halcopyrite Halenite

6 Sulfur in proteins methionine cysteine

7 Natural resources of selenium Selenium can be found in sulfide and sulfate ores in which it partially substitutes sulfur atoms selenomethionine selenocysteine

8 Overall characteristic of elements from VIА group Property О S Se Te Content in the 47, Earth crust, % Atomic radius, 0,066 0,102 0,116 0,135 nm Temperature of -218,75 118,9 220,4 452,0 melting, С Temperature of -182,97 444,6 958,1 1087,0 boiling, С Density, g/ml 1,27 2,06 4,82 6,25 (in solid state) Electronegativity 3,5 2,6 2,5 2,0

9 Electron configuration: [ ] ns 2 (n 1)d 10 np 4 Oxidation states: O: 2, 1, 0, +1, +2 H 2 O; H 2 O 2 ; O 2 ; O 2 F 2 ; OF 2 S, Se, Te (Po): 2, 0, +4, +6 H 2 E; E х ; EО 2 ; EО 3

10 Reactions with water, acids and alkalis 3S + 2H 2 O 2H 2 S + SO 2 (t) Te + 2H 2 O TeO 2 + 2H 2 Po + 2HCl = PoCl 2 + H 2 3S + 6NaOH = Na 2 SO 3 + 2Na 2 S + 3H 2 O (Se,Te)

11 Hydrides Т melting, C Т boiling, C ΔH, kj/mol d (H-E), pm (Н-Э-Н) рк Properties Solvent Reducer Burns in the air Breaks down at О С

12 Compounds of E +4 SO 2 SeO 2 TeO 2 Reducing properties decrease Acidic properties decrease H 2 SO 3 H 2 SeO 3 H 2 TeO 3 2SO 2 + SeO 2 = 2SO 3 + Se reducer oxidizer

13 Compounds of Э +6 SO 3 SeO 3 TeO 3 Reducing properties decrease Acidic properties decrease H 2 SO 4 H 2 SeO 4 Н 6 ТeO 6 H 2 SeO 4 + 2HCl = H 2 SeO 3 + Cl 2 + H 2 O

14 Oxygen

15 In industry: Production of oxygen distillation of liquid air t of boiling O 2 = -183 С t of boiling N 2 = -196 С electrolysis of water solution of KOH: Fe KOH, H 2 O Ni 30% anode (Fe): 4OH - - 4e = O 2 + 2H 2 O catode (Ni): 2H 2 O + 2e = H 2 + 2OH -

16 In the laboratory: 2H 2 O 2 = 2H 2 O + O 2 (Catalysts: МnO 2 ; Pt) Thermal decomposition: 2HgO = 2Hg + O 2 2KClO 3 = 2KCl + 3O 2 2KMnO 4 = K 2 MnO 4 + MnO 2 + O 2

17 Physical and chemical properties of O 2 O 2 is a gas without smell and color Solubility of oxygen Good solubility in organic solvents, Bad solubility in polar solvents: in water: 3.15 ml of О2 in 100 ml of Н2О at 20 С Oxygen is soluble in metals, if it doesn t react with them: at 450 С 1 ml of gold dissolves 77 ml of oxygen O 2 molecule is nonpolar and paramagnetic

18 Oxygen cannot react with: noble gases halogens (except fluorine) silver gold metals from platinum family (except osmium).

19 The usage of oxygen in medicine Mechanical ventilation of lungs (anapnotherapy) Enteral oxygenation «oxygen cocktails» Hyperbaric oxygenation in case of CO poisoning and other conditions like heart attack (infarct).

20 Molecule of oxygen is a ligand in oxyhemoglobin Molecular oxygen has a low solubility in water, and in blood plasma, as well. That is why hemoglobin is used as a transporter of oxygen.

21 Hemoglobin

22 Ozone O 3 light blue gas, t of melting С t of boiling С explosive poisonous Ozone layer: О 2 + hν 2О О 2 + O О 3 О 3 + hν О 2 + О О 3 + O 2О 2

23 O 3 molecule is polar and diamagnetic sp 2 hybridization Production: electric strike 3O 2 2O 3 Solubility: 46 ml of О3 in 100 ml of Н2О at 20 С (15 times higher than that for oxygen)

24 Ozone is a stronger oxidizer than oxygen: O 3 + 2Н + + 2е = O 2 + Н 2 O Е 0 = В O 2 + 4Н + + 4е = 2Н 2 О Е 0 = В In contrast to oxygen it reacts with: O 3 + 2KI + Н 2 SO 4 = O 2 + I 2 + K 2 SO 4 + Н 2 O and 8Ag + 2O 3 = 4Ag 2 O + O 2 (Au, Pt, Ir)

25 The usage of ozone: ozonation of water disinfection whitening agent oxidizer in organic chemistry ozone therapy

26 Types of binary compounds with oxygen a) oxides, containing O 2- (ZnO, Cu 2 O, HgO); b) peroxides, containing O -, (Н 2 О 2, Na 2 O 2 ); c) superoxides, containing O 2 - (КO 2, CsO 2 ); d) ozonides, containing O 3 - (NaO 3 ).

27 Hydrogen peroxide H 2 O 2 H 2 O 2 is a colorless liquid (light blue in the thick layer). H 2 O 2 molecule is polar

28 Hydrogen peroxide H 2 O 2 Disproportioning: 2H 2 O 2 = 2H 2 O + O 20 Oxidative properties: PbS (solid) + 4H 2 O 2 = PbSO 4(solid) + 4H 2 O Reductive properties: Cl 2 + H 2 O 2 = 2HCl + O 2

29 Production of H 2 O 2 In laboratory: 2BaO + O 2 = 2BaO 2 BaO 2 + H 2 SO 4 (conc., cold) = BaSO 4 + H 2 O 2 or BaO 2 + H 2 O + CO 2 = BaСO 3 + H 2 O 2

30 The usage of hydrogen peroxide: antiseptic disinfectant as an oxidizer in reactive technique

31 Sulfur

32 chains -S (rombic) Sulfur S 8 95 С -S (monoclinic) 119 С S (liquid) S (amorphous) «plastic» 445 С boiling S (gaseous) 1500 С S 1 S 8 54% S 6 37% S 4 5% S 2 4%

33 Взаимодействие серы с натрием

34 Взаимодействие серы с цинком

35 Reactions of sulfur with acids and alkalis S + 4HNO 3 4NO 2 + SO 2 + 2H 2 O 3S + 6KOH K 2 SO 3 + K 2 S + 3H 2 O S + H 2 SO 4 3SO 2 + 2H 2 O

36 H 2 S hydrogen sulfide Hydrogen sulfide is a colorless, poisonous gas with a smell of rotten eggs H 2 S molecule is polar

37 Production In industry: H 2 + S H 2 S In laboratory: FeS + 2HCl= FeCl 2 + H 2 S

38 Reductive properties of hydrogen sulfide H 2 S + I 2 = 2HI + S H 2 S + 4Cl 2 + 4H 2 O = 8HCl + H 2 SO 4 2H 2 S (excess) + O 2 = 2H 2 O + 2S 2H 2 S + 3O 2 (excess) = 2H 2 O + 2SO 2

39 Water solution of H 2 S (hydrosulfuric acid) 1. H 2 S + H 2 O HS + H 3 O + ; K 1 = HS + H 2 O S 2 + H 3 O + ; K 2 =

40 Sulfides 1. Soluble in water (cations of alkali and alkaline-earth metals, ammonium): S 2 + H 2 O HS + OH 2. Decomposed in water: Al 2 S 3 + 6H 2 O = 2Al(OH) 3 + 3H 2 S

41 Sulfur dioxide SO 2 SO 2 is a colorless gas with a strong smell, it is stable at heating Production: pyrite combustion 4FeS O 2 = 2Fe 2 O 3 + 8SO 2 In laboratory: Me 2 SO 3 + 2H 2 SO 4 (conc.) = = 2MeHSO 4 + SO 2 + H 2 O

42 In water solution: SO 2 + H 2 O HSO 3 + H + K1 = HSO 3 + H 2 O SO H 3 O + K2 = NaOH (excess) + SO 2 = Na 2 SO 3 + H 2 O 2NaOH + 2SO 2 (excess) = 2NaHSO 3 Sulfite and hydrogensulfite of sodium are preservatives in food production

43 Redox properties of SO 2 SO 2 + 2H 2 S = 3S + 2H 2 O oxidizer SO 2 + 2H 2 O + I 2 = H 2 SO 4 + 2HI reducer

44 The usage of SO 2 it is used as a bleach, as a disinfectant, for sulfuric acid production

45 Thiosulfates 2Na 2 SO 3 + O 2 = 2Na 2 SO 4 Na 2 SO 3 + S = Na 2 S 2 O 3 Na 2 SO 3 S Thiosulfate anion SO 3 S 2

46 Chemical properties of thiosulfates Na 2 SO 3 S + 2HCl = 2NaCl + H 2 O + SO 2 + S Na 2 SO 3 S + 4Cl 2 + 5H 2 O = Na 2 SO 4 + H 2 SO 4 +8HCl Na 2 SO 3 S + I 2 = 2NaI + Na 2 S 4 O 6 (tetrathionate)

47 The structure of tetrathionate anion contains a chain from 4 atoms of sulfur Polythionates are salts polythionic acids H 2 S n O 6 (n = 4 6) They are used as antibiotics

48 The usage of thiosulfates in chemical analysis in medicine as antidotes [Hg(S 2 O 3 ) 4 ] 6- to treat scabies Na 2 S 2 O 3 + 2HCl = 2NaCl + SO 2 + S + H 2 O

49 SO 3 molecule is nonpolar

50 Production: 2SO 2 + O 2 2 SO 3 (600 C, catalyst is V 2 O 5 ) SO 3 + H 2 O = H 2 SO 4 ; H = 130 kj/mol in industry: SO 3 + H 2 SO 4 = H 2 S 2 O 7 (disulfuric acid = oleum)

51 Sulfuric acid H 2 SO 4 is a colorless viscous liquid, the density is 1.84 g/ml, t of melting is 10.4 С. Intermolecular hydrogen bonds are responsible of these properties of sulfuric acid

52 H 2 SO 4 as a dehydrating agent (C 6 H 10 O 5 ) n + mh 2 SO 4 n6c + n5h 2 O mh 2 SO 4

53 H 2 SO 4 + sugar C 12 H 22 O 11 + H 2 SO 4 12C + 11H 2 O H 2 SO 4 C + 2H 2 SO 4 CO 2 + SO 2 + 2H 2 O C 12 H 22 O H 2 SO 4 12CO H 2 O + 24SO 2

54 Reactions between H 2 SO 4 and metals Zn + 2H 2 SO 4 (93-98%) ZnSO 4 + SO 2 + 2H 2 O 3Zn + 4H 2 SO 4 (50%) 3ZnSO 4 + S + 4H 2 O 4Zn + 5H 2 SO 4 (30%) 4ZnSO 4 + H 2 S + 4H 2 O Zn + H 2 SO 4 (<20%) ZnSO 4 + H 2 Cu + 2H 2 SO 4 (93-98%) CuSO 4 + SO 2 + 2H 2 O Cu + H 2 SO 4 (<20%) Fe, Al, Cr + 2H 2 SO 4 (93-98%) without heating

55 Reactions of H 2 SO 4 and metals

56 Reactions of concentrated H 2 SO 4 and nonmetals 2P + 5H 2 SO 4 2H 3 PO 4 + 5SO 2 + 2H 2 O C + 2H 2 SO 4 CO 2 + SO 2 + 2H 2 O S + H 2 SO 4 3SO 2 + 2H 2 O

57 Concentrated H 2 SO 4 as an oxidizer 8HI + H 2 SO 4 4I 2 + H 2 S + 4H 2 O 2HBr + H 2 SO 4 Br 2 + SO 2 + 2H 2 O FeS + H 2 SO 4 FeSO 4 + H 2 S H 2 S + H 2 SO 4 S + SO 2 + 2H 2 O 2FeSO 4 + H 2 SO 4 Fe 2 (SO 4 ) 3 + SO 2 + H 2 O 2KBr + H 2 SO 4 Br 2 + K 2 SO 4 + SO 2 + 2H 2 O

58 Copperas Copper copperas MeSO 4 5(7)H 2 O (Me Cu, Fe, Ni, Mg ) Alum Me +1 Me +3 (SO 4 ) 2 12H 2 O (Me +1 Na, K or NH 4, Me +3 Al, Ga, Cr ) Alum and chrome alum

59 The usage of sulfuric acid and its salts sodium sulfate is a laxative potassium sodium sulfate is a choleretic organic synthesis production of mineral fertilizers: amonium sulfate; superphosphate dehydrating agent

60 Thank you for listening!!!