Chapter 15 The p-block elements(Ⅱ)

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1 Chapter 15 The p-block elements(Ⅱ)
§15.1 The elements of nitrogen family §15.2 The elements of oxygen family

2 §15.1 The elements of nitrogen family
Outline on nitrogen family The elemental substances of nitrogen family The compounds of nitrogen The compounds of phosphorus The compounds of As, Sb and Bi

3 15.1.1 Outline on nitrogen family
The elements of nitrogen family(VA)：N, P, As, Sb, Bi Valence electron 2np3configuration：ns N +5 | -3 P +5 +3 -3 As +5 +3 -3 Sb +5 +3 (-3) Bi (+5) +3 氧化值 最大配 46666 位数 M2O3 酸性 酸性 两性 两性 碱性 NH3 PH3 AsH3 SbH33 BiH33 氨膦胂 SbH BiH MH3 碱性减弱，稳定性下降

4 15.1.2 The elemental substances of nitrogen family
N2 is colorless and odorless gas. N2 is chemically inert. It will react directly with many metals (such as Li, Ca, Mg) when heated to give ionic nitrides. Nitrogen is also easily converted to a liquid (b.p, - °C) and can dissolve in water slightly.195.8

5 The allotropes of phosphorus
隔绝空气 400 °C 高温高压 黑磷 ←⎯ ⎯ ⎯ ⎯ 白磷 ⎯ ⎯ ⎯ ⎯ ⎯ ⎯ → 红磷⎯⎯ net framework， conductive, insoluble in org. solv. P4 : chemicallyrelatively stable, active, autoignite in combust at air, soluble inT>400°C, insoluble nonplolar solv.in org. solv. combustion of P 磷的燃烧 Self-ignite in air白 磷空气中自燃 白磷 红磷

6 N2, P: metalloid， As, Sb: quasi-metal， Bi: metal 白 磷 的 结 构 红 磷 的 结 构
黑磷的结构 N2, P: metalloid， As, Sb: quasi-metal， Bi: metal As

7 .. 15.1.3 The compounds of nitrogen 1. Hydride of nitrogen
ammonia (NH3) molecular structure： hybridization, triangular pyramid molecular structure 3N：sp .. N 10 0.8 pm 107.3o H H H

8 NH3 + H2O NH + OH NH3 ⋅ H2O 4NH 3 + 3O 2 (pure) → 2N 2 + 6H 2 O
Preparation： In laboratory： 2NH 4 Cl + Ca(OH) 2 ⎯ CaCl 2 + 2H 2 O + 2NH 3 (g)⎯→ 雨林木风1 In industry process: 450~500°C 30MPa Fe N 2 + 3H 2 ⎯⎯ ⎯ ⎯ ⎯ ⎯ ⎯ ⎯ → 2NH 3⎯ Chemical properties： ① Soluble in water forming monoprotic weak base NH3 + H2O NH + OH + 4 _ NH3 ⋅ H2O ② Strong reducing ability 4NH 3 + 3O 2 (pure) → 2N 2 + 6H 2 O 4NH 3 + 5O 2 (air) ⎯ c 4 NO + 6H 2 O⎯→ 800 Pt o

9 幻灯片 8 雨林木风1 Nobel prize.战犯 webuser,

10 H + NH 3 → NH 4 Ag + 2 NH 3 → [Ag(NH 3 ) 2 ] NH2-NH2联氨(肼)，NH 亚氨基，N 氮化物
③ coordination reaction + H + NH 3 → NH 4 + Ag + 2 NH 3 → [Ag(NH 3 ) 2 ] + + ④ Substitution reaction 2NH 3 + 2Na ⎯⎯ → 2NaNH 2 + H 2⎯ 570° C 催化 NH2-NH2联氨(肼)，NH 亚氨基，N 氮化物 hydrazine NH2OH 羟氨, Ammonium hydroxide

11 3 hybridization, tetrahedronN：sp
Ammonium salts ① Most ammonium salts are colorless crystals and soluble in water hydrolysis： NH + H2O + 4 H3 +O + NH3 + The structure of NH ： 3 hybridization, tetrahedronN：sp + 4 H N H Identification of NH4 +： H Litmus paper method(石蕊试纸法)：pH range: 5 -8 遇酸变 红， 遇碱变蓝 Nessler reagent (K2HgI4): phenomena is 红棕到深褐 Hg + 4 2− − − NH + 2[HgI 4 ] + 4OH [O NH2 ]I(s) +7I + 3H 2 O Hg

12 ammonium salts of non-oxidizing volatile acids
② Poor thermal stability ammonium salts of non-oxidizing volatile acids NH 4 Cl ⎯ NH 3 (g) + HCl(g)⎯→ Δ (NH 4 ) 2 CO 3 ⎯ 2 NH 3 (g) + CO 2 (g) + H 2 O(g)⎯→ Δ NH 4 HCO 3 ⎯ NH 3 (g) + CO 2 (g) + H 2 O(g)⎯→ Δ ammonium salts of non-oxidizing and non- volatile acids (NH 4 ) 3 PO 4 ⎯ 3NH 3 (g) + H 3 PO 4⎯→ Δ (NH 4 ) 2 SO 4 ⎯ NH 3 (g) + NH 4 HSO 4⎯→ Δ

13 (NH4 ) 2 Cr2 O 7 ⎯ N 2 (g) + Cr2 O3 (s) + 4H 2 O⎯→
ammonium salts of oxidizing acids NH4 NO2 ⎯ N 2 (g) + 2H 2 O⎯→ Δ (NH4 ) 2 Cr2 O 7 ⎯ N 2 (g) + Cr2 O3 (s) + 4H 2 O⎯→ Δ 5NH4 NO3 ⎯⎯ → 4N 2 + 2HNO3 + 9H 2 O⎯ 240°C 催化剂 NH4 NO3 ⎯ N 2 O + 2H 2 O⎯→ Δ

14 2. Oxygen compounds of nitrogen • Nitrogen oxide (NO) Colorless gas
2 (2σ)2(1σ) 2 (3σ) 2 (4σ) 2(1π)4(5σ) 1 (2π) : paramagnetic Chemical properties： 2NO + O 2 → 2NO 2 2NO + Cl 2 → 2NOCl(氯化亚硝酰) 3Fe + NO + 4H → 3Fe + NO + H 2 O 2+ N2 + O2 → NO2 - 3 + 3+ [ Fe(H 2 O) 6 ] + NO → [Fe(NO)(H2 O)5 ] + H 2 O brown 2+ 2+ Preparation： 4NH 3 (g) + 5O 2 (g) ⎯⎯ → 4 NO(g) + 6H 2 O⎯ 800° C 铂丝网 3Cu + 8HNO 3 (稀) → 3Cu(NO 3 ) 2 + 2NO + 4H 2 O

15 Π • Nitrogen dioxide (NO2) molecular structure： N: hybridization
22p3;2s 3 Π 2sp hybridization Π Properties： σ σ toxic, brown gas 冷却 Θ <02NO（红棕色） C N 2 O（无色）ΔHm 24 140 ① ② ο 3NO 2 + H 2 O → 2HNO 3 + NO react with bases 2NO 2 + 2NaOH → NaNO 3 + NaNO 2 + H 2 O ③ ④

16 3. Nitrogen oxyacids and related salts
• Nitrous acid (HNO2) Molecular structure： N：sp2 hybridization： H π 。 102 σ σ O N 。 110 O: 22p42s O Preparation： 冷NaNO 2 + H 2SO 4 ⎯⎯→ NaHSO 4 + HNO 2 NO + NO 2 + H 2 O ⎯⎯ → 2HNO 2⎯ 冷冻 heat

17 Chemical properties： NO+NO2 K a = 6.0×10 nitrous acid (HNO2)
① unstable H 2O + N 2O3 (blue) ② weak acid H 2 O + NO + NO 2 2HNO 2 _ H + NO 2 + HNO 2 NO+NO2 K a = 6.0×10 _ 4 nitrous acid (HNO2)

18 Preparation: treating the acidic oxides with a base
• Nitrite (亚硝酸盐） Preparation: treating the acidic oxides with a base NO2 + NO + NaOH⎯ 2NaNO2 + H2O⎯→ Properties： ① Most nitrites are colorless and soluble in water (except for AgNO2) ② redox properties (EA (HNO2 /NO) = 1.04V) 2NO+ I2 + 2H2O 2NO + 2I + 4H + - 2 - 主 NO + Fe + 2HNO + Fe + H2O NO2 + 2MnO4 + 6H5NO3 + 2Mn + 3H2O ③ metals having low activity correspond to nitrites of low thermal stability 金属活泼性差,对应亚硝酸盐稳定性差 2+ + 3+ - 2 AgNO2<NaNO2 ( ) +的极化力 M

19 Π Π ? • Nitric acid (HNO3) Structure： σ σ σ Physical properties ：
2 hybridizationN：sp Structure： Π 4 3 Π σ σ σ 6 4 Π ? z2 Physical properties ： Pure nitric acid：a colorless liquid with a pungent, -3)choking odor (density 1.53g·cm Concentrated nitric acid： 69% HNO3 by mass， -3). Pure HNO is colorless, but some(density 1.4g·cm 3 acid decomposes during the preparation to give brown gas NO2 which colors the product.

20 幻灯片 18 z2 也有人认为是pai46 zho,

21 ⎯→4HNO3 + 3C ⎯ 3CO 2 (g) + 4NO(g) + 2H 2 O
Chemical properties of HNO3 ① Powerful oxidizing agent HNO3 + 非金属单质 ⎯ 相应高价酸 + NO⎯→ ⎯→4HNO3 + 3C ⎯ 3CO 2 (g) + 4NO(g) + 2H 2 O ⎯→5HNO3 + 3P + 2H 2 O ⎯ 3H 3 PO 4 + 5NO(g) ⎯→2HNO3 + S ⎯ H 2SO 4 + 2NO 10HNO3 + 3I 2 ⎯ 6HIO3 + 10NO + 2H 2 O⎯→

22 Concentrated nitric acid will oxidize almost all
metals, but the exact product depends on the metal z1 (the reducing agent) and acid concentration. Cu + 4HNO3 (浓) Cu(NO3 ) 2 + 2NO 2 + 2H 2 O 3Cu + 8HNO3 (稀) 3Cu(NO3 ) 2 + 2NO + 4H 2 O Copper reacts with concentrated nitric acid Au, Pt, Nb, Ta etc don’t react with HNO3

23 当硝酸的浓度在8mol/L以上时,还原的产物主要是NO2.这是因为硝酸越浓,氧化性越强,反应过程中生成的低价态的氮的化合物,在强的氧化气氛中
幻灯片 20 z1 当硝酸的浓度在8mol/L以上时,还原的产物主要是NO2.这是因为硝酸越浓,氧化性越强,反应过程中生成的低价态的氮的化合物,在强的氧化气氛中 不能存在,继续被氧化成高价的氮的化合物——NO2。当硝酸变稀时，它的氧化性也较弱，氮的低价氧化物能够存在，所以主要产物为NO。 参考资料：人民教育出版社高中化学第二册 教师教学用书第17页 zho,

24 reactive metal (strong reducing agent)：
Zn + 4HNO3 (浓) Zn(NO3 ) 2 + 2NO 2 + 2H 2 O 3Zn + 8HNO3 (稀1 : 2) 3Zn(NO3 ) 2 + 2NO + 4H 2O 4Zn + 10HNO3 (较稀,2mol · L ) 4Zn(NO3 ) 2 + N 2 O + 5H 2 O -1 4Zn + 10HNO3 (很稀,1 : 10) 4Zn(NO3 ) 2 + NH 4 NO 3 + 3H 2 O U1 orderliness：HNO3越稀，金属越活泼， HNO3 被还原的 氧化值越低。 +4 NO2 HNO2 NO N2O N2NH3

25 都是铜和硝酸反应，为什么和稀硝酸反应产物是一氧化氮，和浓硝酸反应产物是二氧化氮？ 还有什么类似的反应吗？
幻灯片 21 U1 都是铜和硝酸反应，为什么和稀硝酸反应产物是一氧化氮，和浓硝酸反应产物是二氧化氮？ 还有什么类似的反应吗？ 解释:当硝酸和金属反应时,硝酸被还原程度取决与酸的浓度和还原剂的强弱.对于同一种还原剂,酸越稀,被还原的程度越大. 例如在铜与浓硝酸的反应中,+5价的N被还原成+4价的N 铜与稀硝酸的反应中,+5价的N被还原成+2价的N 浓硝酸与金属反应时,最初生成NO,但由于硝酸浓度很大,使平衡强烈的向左移动,主要产物为NO2,当稀硝酸和金属反应时,由于硝酸浓度小,平衡向 右移动,主要产物为NO. 当硝酸的浓度在8mol/L以上时,还原的产物主要是NO2.这是因为硝酸越浓,氧化性越强,反应过程中生成的低价态的氮的化合物,在强的氧化气氛中 不能存在,继续被氧化成高价的氮的化合物——NO2。当硝酸变稀时，它的氧化性也较弱，氮的低价氧化物能够存在，所以主要产物为NO。 参考资料：人民教育出版社高中化学第二册 教师教学用书第17页 User,

26 TNT(三硝基甲苯) CH 3C 6 H 5 + 3HNO 3 ⎯⎯⎯→ CH 3C 6 H 2 (NO 2 ) 3 + 3H 2 O
●Cold concentrated nitric acid can passivate metal like Fe, Al and Cr ●aqua regia (kingly water)：(氧化配位溶解) Au + HNO 3 + 4HCl ⎯ H[AuCl 4 ] + NO + 2H 2 O⎯→ 3Pt + 4HNO HCl → 3H 2 [PtCl 6 ] + 4NO + 8H 2 O ② Thermal decomposition. It should be kept in brown bottles 4HNO 3 ⎯ 4NO 2 + O 2 + 2H 2 O⎯→ ③ Nitration reaction H 2SO 4 C 6 H 6 + HNO 3 ⎯ ⎯ ⎯ → C 6 H 5 NO 2 + H 2 O⎯ CH 3C 6 H 5 + 3HNO 3 ⎯⎯⎯→ H 2SO 4 △ CH 3C 6 H 2 (NO 2 ) 3 + 3H 2 O TNT(三硝基甲苯)

27 Π σσ σ − Π • nitrate The structure of NO3 ： Π O: four p orbitals 6 4
22p42s The structure of NO3 ： - 2 hybridizationN：sp Π σσ σ − O N O O 6 4 Π Π 6 4 four p orbitals c.f.: CO3 2-

28 acidic conditions, solid nitrate has oxidation ability
Properties： ① Soluble in water； ② The nitrate solution has oxidation ability under acidic conditions, solid nitrate has oxidation ability under high temperatures； ③ Poor thermal stability Activity order：K Ca Na Mg Al Zn Fe Sn Pb (H) Cu Hg Ag Pt Au Δ K ~ Mg： 2NaNO 3 ⎯⎯→ 2NaNO 2 + O 2 Δ Mg ~ Cu： 2Pb(NO3 ) 2 ⎯⎯→ 2PbO + 4NO 2 + O 2 Δ After Cu: 2AgNO3 ⎯ Cu以后： ⎯→ 2Ag + 2NO 2 + O 2

29 E (HNO2 /NO) = 1.04V E (NO /NO) = 0.96V
A comparison of properties of nitrous acid and its salts with those of nitric acid and its related salts : Acidic： HNO 3 > HNO 2 ● Oxidization ability：HNO 3 < HNO 2 ● E (HNO2 /NO) = 1.04V E (NO /NO) = 0.96V - 3 Thermal stability of acids：HNO3 > HNO 2 ● Thermal stability of active metal salts: MNO2>MNO3 (M = active metals)

30 15.1.4 The compounds of phosphorus
1. Hydride of phosphorous (膦 PH3) 雨林木风3 Molecular structure：similar to NH3 ·· Ｐ H H H Preparation： PH 4 I + KOH ⎯ PH 3 + H 2 O + KI ⎯→ 碘化鏻 ⎧Mg 3 N 2 + 6H 2 O ⎯ 2NH 3 + 3Mg(OH) 2 ⎯→ ⎨ ⎯→Mg 3 P2 + 6H 2 O ⎯ 2PH 3 + 3Mg(OH) 2 ⎩ P4 + 3KOH + 3H 2 OPH 3 + 2KH2 PO 2 potassium hypophosphite 次磷酸钾

31 responsible for wildfile
幻灯片 26 雨林木风3 responsible for wildfile webuser,

32 Properties：colorless and exceedingly poisonous
gas with a garlic odor, a strong reducing agent： -3 PH 3 + 2O 2 ⎯ H 3 PO 4⎯→ 2. The oxides of phosphorus O2(足) O 2 ( 不足 ) O2 Δ P4 ⎯⎯ ⎯ ⎯→ P4 O 6 ⎯⎯ → P4 O10⎯ 磷酸酐 亚磷酸酐 P4O6 P4O10

33 Properties： P4 O 6 + 6H 2 O(冷) ⎯ 4H 3 PO 3⎯→
P4O6: white, light volatile, waxy crystal P4O10: white crystal, strong water absorption ability P4 O 6 + 6H 2 O(冷) ⎯ 4H 3 PO 3⎯→ P4 O 6 + 6H 2 O(热) ⎯ 4H 3 PO 4 + PH 3⎯→ disproportionation reaction 5P4 O H 2 O(热) ⎯ 12H 3 PO 4 + 8P⎯→ 歧化反应 P4 O10 + 6H 2 O ⎯ 4H 3 PO 4⎯→ P4 O10 + 6H 2SO 4 ⎯ 6SO 3 + 4H 3 PO 4⎯→ dehydration P4 O HNO3 ⎯ 6N 2 O 5 + 4H 3 PO 4⎯→

34 3. Phosphorus oxyacids and their salts
+1 • Hypophosphorous acid ( H3PO2) and its salts O 次磷酸 Structure： P H HO H Properties: monoprotic medium acid Ka -2=1.0×10 EA (H 3 PO 3 /H 3 PO 2 ) = − 0.499V Strong reducing agent −2−EB (HPO 3 /H 2 PO 2 ) = − V H3PO2 can reduce salts of heavy metals to elemental substances, e.g., AgNO3 HgCl2 CuCl2 NiCl2 Cu Ni Ag Hg

35 • Phosphorous acid (H3PO3) and its salts
+3 • Phosphorous acid (H3PO3) and its salts O 亚磷酸 Structure： P HO H K 1 = 6.3× 10 −7 K 2 = 2.0× −2 Properties: binary medium acid: EA(H 3PO 4 /H 3PO 3 ) = − 0.76V Strong reducing agent： 3-2- EB (PO 4 /HPO 3 ) = − 1.12V H 3PO 3 + 2Ag + H 2O + H 3PO 4 + 2Ag + 2H + 受热歧化 4H 3 PO 3 ⎯⎯→ 3H 3 PO 4 + PH 3 Δ

36 • Phosphoric acid ( H3PO4 )
+5 • Phosphoric acid ( H3PO4 ) 磷酸 O Structure： P HO OH OH Property：medium triprotic acid −8 −3 Ka2 = 6.2 ×10 Ka1 = 6.7 ×10 Ka3 = 4.5 × 10 −1 3 Speciality：Phosphoric acid can be converted to pyrophosphoric acid(焦磷酸), polyphosphoric acid (聚磷酸) and polymetaphosphoric acid ((聚)偏磷酸) by condensation reaction.

37 • Pyrophosphoric acid ( H4P2O7 )
焦磷酸 O O H + HO HO P O P OH OH OH O O OH +H2O HO P O P OH OH

38 polyphosphoric acid (n个磷酸脱n-1个H2O) n=2 pyrophosphoric acid (焦磷酸)
n=3 tripyrophosphoric acid (三(聚)磷酸) O O O H + HO H + HO HO P O P O P OH OH OH OH O O O OH + 2H 2 O HO P O P O P OH OH OH

39 • (poly)metaphosphoric acid (聚)偏磷酸
(聚)偏磷酸 (n H3PO4 molecules lose n H2O molecules) 偏磷酸：HPO3(n=1)，四(聚)偏磷酸：(HPO3)4 O O O O HO P O H + HO P OH HO P O P OH O O H + O O H + O HO P O P OH O OH +H O P O O HO P OH +4H2O O O

40 Polyphosphate can be used as ligands:
CaCO 3 (s) + P3 O ⎯ [CaP3 O10 ] + CO⎯→ 5- 10 3− 2- 3 O O O O P O P O P O P O O O O O Ca Ca 硬水软化 P2 O 2+ 4- 7 ⎯ ⎯ → Cu 2 P2 O（ s, 浅蓝）⎯ 7 Cu P2 O 4- 7 ⎯ ⎯ →[Cu(P 2 O 7 ) 2 ] （蓝）⎯ 6−

41 The general rules of the change of acidity:
•Acidity increases with increasing degree of polymerization H5P3O10 H4P2O7H3PO4 ×10 6.7×10 ×10 6.2×10 ×10 4.5×10 -104.8×10 Ka1 10 -310 -2 Ka2 Ka3 Ka4 •For oxyacids of an element showing different oxidation numbers, the one with high oxidation number is more acidic, except for ones of phosphorous 同一元素不同氧化态，高价偏酸，但磷酸 的含氧酸例外。 +3+1+5 H3PO3 H3PO2 H3PO4 Ka1 6.3×10 1.0×10 6.7×10 -2 -2 -3

42 Phosphate 正盐酸式盐 III M 3 PO 4 M 2 HPO 4M H 2 PO 4 ( 除 K , Na , NH 4 )
Mostly insoluble solubility Mostly soluble + + + ( 除 K , Na , NH 4 ) Na 3 PO 4 Na 2 HPO 4 PH>7PH>7 水解为主 水解 > 解离 NaH 2 PO 4 PH<7 水解 < 解离 acidity/basicity of aqueous solution stability stable relatively unstable

43 4. Halides of phosphorous
PX3 PX5 Structure: pyramidal bipyramidal (gas mol.) (gas molecule) types of unequivalent hybridization： PCl 3 sp 3dsp PCl5 3 Molecular crystal Ionic crystal

44 There exist [PCl4 and [PCl6] ions in solid PCl5
PCl5 ionic crystal - There exist [PCl4 and [PCl6] ions in solid PCl5 +] + Cl [PCl4 +：P：sp3 hybridization] P tetrahedron Cl Cl Cl - - [PCl6] 3d2 hybridization：P：sp Cl Cl Cl P octahedron Cl Cl Cl - Similarly, there exist [PBr4 and [PBr6] ions in solid PBr5 and the gas molecule has the bipyramidal structure. +]

45 The important property：hydrolysis
PCl 3 + 3H 2 O ⎯ H 3 PO 3 + 3HCl⎯→ (so do PBr3, PI3 ) 2P + 3Br2 + 6H 2 O ⎯ 2H 3PO 3 + 6HBr⎯→ (H3PO3 or HBr can be prepared in this way) PCl 5 + 4H 2 O ⎯ H 3 PO 4 + 5HCl⎯→

46 15.1.5 The compounds of As, Sb and Bi
1. Hydrides of As, Sb and Bi (NH3, PH3) AsH3 SbH3 BiH3 胂 月弟 月必 Stability high low basicity strong weak b.p and m.p low high (Fw↑) Chemical Properties： Autoignition: 2AsH 3 + 3O 2 ⎯ As 2 O 3 + 3H 2 O⎯→ Δ ⎯→Decomposition： 2AsH 3 ⎯缺O 2As + 3H 2

47 Application of the chemical properties of AsH3：
Marsh test (马氏试砷法)： An arsenic-containing solution is treated with z3 zinc granules and HCl acid, the evolved gas is passed through a heated tube, where it decomposes to the element and leaves a shiny film of As on the glass. 2AsH 3 ⎯ 2As + 3H 2⎯→ 砷镜 Gooch test (古氏试砷法)： 2AsH AgNO 3 + 3H 2 O ⎯⎯→ (strong reducing agent) As 2 O HNO Ag(s)

48 the resulting H2 reduces As to AsH3, then AsH3 decomposes into As
幻灯片 42 z3 the resulting H2 reduces As to AsH3, then AsH3 decomposes into As zho,

49 2. Oxides and the related hydroxides of As, Sb and Bi
Oxides and hydroxides of M(III) As2O3(白) 砒霜、剧毒 微溶 solubility in water 两性偏酸 Bi2O3 Sb2O3 corresponding oxides (white) (yellow) 难溶 两性 极难溶 碱性 types of crystal structure existing form at room tempt. molecular molecular ionic As4O6 Sb4O6 Bi(OH)3 As(OH)3 Sb(OH)3 H3AsO3碱性 两性偏碱 (微两性) 两性偏酸 Corresponding hydroxides

50 ⎯→M 2 O 3 + 6H ⎯ 2M + 3H 2 O M 2 O 3 + 6OH ⎯ 2MO + 3H 2 O⎯→ MO + 3H
Amphiprotic Oxides M2O3( M = As Sb, ≠ Bi)： ⎯→M 2 O 3 + 6H ⎯ 2M + 3H 2 O + 3+ M 2 O 3 + 6OH ⎯ 2MO + 3H 2 O⎯→ - 3- 3 亚砷酸盐. Hydroxides of III (M M = As, Sb, Bi)： M + 3OH 3+ − M(OH) 3 MO + 3H + 3- 3 H 3 MO 3 Sb(OH)3 + 3H ⎯ 2Sb + 3H 2 O⎯→ + 3+ Sb(OH)3 + OH ⎯ Sb(OH)⎯→ - - 4 Bi(OH)3 在40%NaOH溶液中，加热才溶解

51 As2 O5 (白) Sb 2 O 5 (淡黄) Bi2O5 (红棕)
Oxides and hydroxides of M(V) As2 O5 (白) Sb 2 O 5 (淡黄) Bi2O5 (红棕) extremely unstable corressponding H 3 AsO 4 hydroxides medium strong H[Sb(OH) 6 ] monoprotic weak acid triprotic acid 一元弱酸 三元中强酸 Ka1 = 5.7 × 10 −3 K a = 4× 10 -5 Ka2 = 1.7 × 10 −7 Ka3 = 2.5 × 10 −12

52 Summary： As 2O 3 H 3AsO 3 Sb 2O 3 Sb(OH) 3 Bi2O 3 Bi(OH) 3 As 2O 5
(两性偏酸) (两性) (碱性) As 2O 5 H 3AsO 4 Sb 2O 5 H[Sb(OH) 6] Bi2O 5 (极不稳定) (酸性) (两性偏酸)

53 3. The redox properties of compounds of As, Sb and Bi
Reducibility of M(III) (由As到Bi还原性减弱) 4< pH <9 AsO + I 2 + 2OH ⎯⎯ ⎯ → AsO + 2I + H 2 O⎯ 3- 3 - 3- 4 - Sb(OH) + Cl 2 + Na + 2OH ⎯⎯→ - 4 + − Decreasing reducibility Na[Sb(OH)6 ](s,白) + 2Cl + 定性测Na - 还 原 性 减 弱 Sb(OH) + 2[Ag(NH3 ) 2 ] + 2OH ⎯⎯→ - 4 + − Sb(OH) + 4NH 3 + 2Ag(s) - 6 Bi(OH)3 + Cl 2 + 3NaOH ⎯⎯→ NaBiO3 (s, 土黄) + 2NaCl + 3H 2 O H2O2 can be used instead of Cl2

54 H 3 AsO 4 + 2I + 2H ⎯⎯⎯→ H 3AsO3 + I 2 + H 2 O
Oxidizing ability of M(V)(由As到Bi氧化性增强) H 3 AsO 4 + 2I + 2H ⎯⎯⎯→ + - 强酸性 Oxidizing ability increases 都 有 氧 化 性 且 增 强 H 3AsO3 + I 2 + H 2 O Na[Sb(OH)6 ] + 2I + 6H ⎯⎯→ - + I 2 + Sb + 6H 2 O + Na 3+ + NaBiO3 + 6HCl(浓) ⎯⎯→ Cl 2 + BiCl3 + NaCl + 3H 2 O 5NaBiO3 + 2Mn 2+ + 14H ⎯⎯→ + 2+)(鉴定Mn 2MnO + 5Bi + 7H 2 O + 5Na - 4 3+ +

55 E =0.5748V I2 2I E =0.5345V H 3 AsO 4 + 2H + 2e H 3 AsO3 + H 2 O
- H 3 AsO3 + H 2 O E =0.5748V + 2 0.0592V E = E + 2 { c ( H 3 AsO 4 )}{ c ( H )} lg { c ( H 3 AsO 3 )} - I2 -+2e 2I E =0.5345V H3AsO4 shows obvious oxidizing ability at low pH 在强酸性的溶液中才有明显 氧化性。

56 reducing ability increase 还原性增强
Summary： reducing ability increase 还原性增强 basicity increase 碱性增强 acidity increases Basicity increases 酸 性 增 强 As(Ⅲ) Sb(Ⅲ) Bi(Ⅲ) 碱 性 增 强 As(Ⅴ) Sb(Ⅴ) Bi(Ⅴ) acidity increase 酸性增强 oxidizing ability increase 氧化性增强

57 • Oxidizing ability (weak)
4. Salts of As, Sb and Bi • Hydrolysis 3+ + 3H 2 O ⎯ H 3 AsO 3 + 3H⎯→ + As 3+ + Cl + H 2 O ⎯ MOCl(s,白) + 2H⎯→ - + M M = (Sb, Bi) • Oxidizing ability (weak) 2Sb + 3Sn ⎯ 2Sb + 3Sn⎯→ 3+ 2+ 3+)(鉴定Sb 2Bi + 3Sn(OH) + 6OH ⎯⎯→ 3+ 2- 4 − 2Bi + 3Sn(OH) 2− 6 3+)(鉴定Bi

58 Properties： • insoluble in water and dilute acid
5. Sulfides of As, Sb and Bi As2S3(黄) As2S5(黄) Sb2S3(橙) Sb2S5(橙) Bi2S3(黑) Bi2S5 Properties： • insoluble in water and dilute acid • soluble through coordination reaction (conc.HCl) -3-+Sb 2S3 + 12Cl + 6H ⎯ 2SbCl 6 + 3H 2S⎯→ As2S3 不溶 . As2S5 Bi 2S3 + 8Cl + 6H ⎯ 2BiCl + 3H 2S⎯→ −+−Sb 2S5 + 12Cl + 10H ⎯ 2SbCl 6 + 5H 2S⎯→ - + - 4 • soluble in oxidizing acid (HNO3) Bi 2 S3 + 2NO + 8H ⎯ 2Bi⎯→ - 3 + 3+ + 3S + 2NO + 4H 2 O

59 • soluble in oxidizing base
• soluble in base -3-3- ⎯→M 2S3 + 6OH ⎯ MO 3 + MS3 + 3H 2 O NaOH 硫代亚xxx 酸盐 ⎯→4M 2S5 + 24OH ⎯ 3MO + 5MS + 12H 2 O - 3- 4 3- 4 硫代x x 酸盐 (M=As，Sb，≠ Bi) M 2S3 + 3S 2- M 2S5 + 3S 2- 3- 3 4 2MS (M=As, Sb, ≠Bi) Na2S • soluble in oxidizing base M 2S3 + 3Na 2 S2 → 2Na 3 MS 4 + S (M=As, Sb, ≠Bi)

60 §15.2 The elements of oxygen family 15.2.1 Outline on oxygen family
Oxygen and the related compounds Sulfur and the related compounds

61 15.2.1 Outline on oxygen family (VIA)
element sulfur selenium tellurium polonium O S Se Te Po element symbol radioactive metal nonmetal quasi-metal character natural existing form elemental substance or mineral accrete with sulfide of heavy metals valence electron configuration 2s 2p 2 4 3s 3p 2 4 4s 4p 2 4 5s 5p 2 4 6s 6p 2 4 3.44 2.58 2.55 2.10 2.0 electronegativity -2, (-1) ± 2,4,6 ± 2 ,4,6 2,6 oxidation number 2 ,4,6 red Se (molecular) 雨林木风4 chain likemetallic gray Se (chain like) crystal type molecular

62 幻灯片 55 雨林木风4 混合键型晶体：共价键，分子间作用力等 webuser,

63 夏威夷劳厄火山裂缝喷 气孔附近的天然硫沉积 天然硫晶体

64 chemical reactivity： low stability：high acidity：weak
Se Te Covalent hydride H2O H2S H2Se H2Te chemical reactivity： low stability：high acidity：weak mp and bp： the highest low high low strong

65 15.2.2 Oxygen and the related compounds
1. Oxygen ( O2) Molecular orbital configuration： (σ 1s ) (σ 2 * ) (σ 2s ) (σ 2 2 * ) (σ 2 p ) (π 2 p ) (π 2 2 4 * ) 2 1s 2s 2p O π • O ••• 3 2 Two 2-center-3-electron π bonds • Under acidic condition：strong oxidizing agent + - O 2 + 4H + 4e2H 2O E = 1.229V basic condition： - O 2 + 2H 2O + 4e = 0.401V - 4OH E

66 2. Ozone (O3)：one of the allotropes of oxygen
2 hybridization Structure： The central oxygen: sp obond angle：117 -30C•mμ=1.8×10 4 a polar elemental substance Π 3 Properties： • unstable -1 2O 3 3O 2 Δr H m = − kJ • mol • oxidizing ability + - O 3 + 2H + 2eO 2 + H 2O EA = 2.075V O 3 + H 2 O + 2e O 2 + 2OH − EB = 1.247V - O 3 + 2I + 2H ⎯ I 2 + O 2 + H 2 O⎯→ + -

67 3. Hydrogen peroxide (H2O2)
Structure： 97pm 97 o 149pm 94 O O o O: 3 sp hybridization 97 o H Properties： weak acidity• HO + H + 10 K K 1 = 2.0× ， 2 ≈10 - 2 -12 -25 H 2O 2 H 2O 2 + Ba(OH)2 BaO2 + 2H 2O • unstable + O 2 △rHm = -196kJ ⋅ mol2H 2O -1 2H 2O 2

68 we can see the oxidation ability of H2O2 is strong
• redox property O V H 2 O V H 2 O in acidic solution： H 2O 2 + 2Fe + 2H ⎯ 2Fe + 2H 2O⎯→ 2+ + 3+ oxidant 4H 2 O 2 + PbS(s, 黑) ⎯ PbSO 4 (s,白) + 4H 2 O⎯→ 5H 2 O 2 + 2MnO + 6H ⎯ 2Mn⎯→ - 4 + 2+ + 5O 2 + 8H 2 O reducer HO + H 2 O + 2e 3OH , EB = 0.867V - 2 - - in basic solution： 3H 2 O 2 + 2Cr(OH) + 2OH ⎯ 2CrO + 8H 2 O⎯→ - 4 - 2- 4 we can see the oxidation ability of H2O2 is strong and reduction ability is weak；So, it can be used as bactericide.

69 Sulfur and related compounds
15.2.3 Sulfur and related compounds 1. Elemental sulfur: a few allotropic forms rhombic sulfur monoclinic sulfur plastic sulfur (斜方硫)(单斜硫 )(弹性硫) density/g cm1.99 coloryellowbufffast cooling of liquid (浅黄) sulfur heated above stability< 94.5℃> 94.5℃190℃ Structure： a puckered S8 ring structure 3S：sp hybridization for both 斜方硫 and 单斜硫

70 S(单斜 ) ⎯⎯⎯→ 弹性硫 S(斜方) The formation of plastic sulfur
monoclinic sulfur rhombic sulfur The formation of plastic sulfur z4 oC94.5 190°C S(单斜 ) ⎯⎯⎯→ 弹性硫 S(斜方)

71 单质硫加热熔化后，温度升至160℃，S8环开始断开，并聚合成中长链大分子，因而液体颜色变暗，粘度显著增大。当温度达到190℃左右，倒入
幻灯片 63 z4 单质硫加热熔化后，温度升至160℃，S8环开始断开，并聚合成中长链大分子，因而液体颜色变暗，粘度显著增大。当温度达到190℃左右，倒入 冷水中迅速冷却，可以得到弹性硫。此时，由于骤冷，长链状硫分子来不及成环，仍以绞结的长链存在于固体中，因而固体具有弹性。试验现象 如上图 zho,

72 Hg + S ⎯ HgS⎯→ S + 3F2 (过量) ⎯ SF6⎯→
Chemical properties of elemental sulfur • Chemical reaction with metallic elements 2Al + 3S ⎯ Al 2 S3 Fe + S → FeS⎯→ Hg + S ⎯ HgS⎯→ S + 3F2 (过量) ⎯ SF6⎯→ • Chemical reaction with Δ SCl non-metallic elements (H, S + Cl 2 ⎯⎯→ 2 O, C, P, halogen ) S + O 2 ⎯ SO 2⎯→ • reacts with oxidizing acid S + 2HNO 3 ⎯ H 2 SO 4 + 2NO(g)⎯→ S + 2H 2 SO 4 (浓) ⎯ 3SO 2 (g) + 2H 2 O⎯→ • reacts with base Δ 3S + 6NaOH ⎯ 2Na 2 S + Na 2 SO 3 + 3H 2 O⎯→ Δ 4S(过量) + 6NaOH ⎯⎯→ 2Na 2 S + Na 2 S 2 O 3 + 3H 2 O

73 2. Hydrogen sulfide and other sulfides • Hydrogen sulfide H2S
Structure：analogous to that of H2O HProperties： 2S is a colorless gas that smells like rotten eggs. H2S is a highly toxic substance. It dissolves to a small extent in water, where it behaves as a biprotic weak acid. H2S is a reducing agent: 0.3002V 0.1576V0.4497V0.144V H 2SO3SH 2S 0.3478V EA SO 2- 4

74 Fe2S3 FeS H 2S + 2Fe ⎯ S + 2Fe + 2H⎯→ • reacts with air (O2) 完全
2H 2 S + 3O 2 ⎯⎯ → 2H 2 O + 2SO 2⎯ 2H 2 S + O 2O+S 2 • reacts with medium oxidant 不完全 → 2H⎯⎯ ⎯⎯ Fe2S3 H 2S + 2Fe ⎯ S + 2Fe + 2H⎯→ 3+ 2+ + FeS H 2 S + X 2 ⎯ S + 2X + 2H⎯→ - + (X = Cl, Br, I) S • reacts with strong oxidant→ products SO4 2- H 2S + 4X 2 (Cl 2 , Br2 ) + 4H 2 O ⎯ H 2SO 4 + 8HX⎯→ 5H 2S + 2MnO + 6H ⎯ 2Mn⎯→ - 4 + 2+ + 5S + 8H 2 O 5H 2S + 8Mn O + 14H ⎯ 8Mn⎯→ - 4 + 2+ + 5SO + 12H 2 O 2- 4

75 • Metal sulfides + 3S + 6H 2 O ⎯ 2M(OH) 3 + 3H 2 S⎯→ 2M (M = Al, Cr)
Color：( Most metal sulfides are black, only a minority are special) , e.g.: SnS (brown),SnS2 (yellow), As2S3 (yellow), Sb2S3 (orange), Sb2S5 (orange),As2S5 (yellow), MnS (pale red), ZnS (white),CdS (yellow) Facile hydrolysis (no mater it is soluble or insoluble)： Compounds of the most facile hydrolysis are Cr2S3 and Al2S3 3+ + 3S + 6H 2 O ⎯ 2M(OH) 3 + 3H 2 S⎯→ 2- 2M (M = Al, Cr)

76 MnS, FeS, CoS, NiS, ZnS MS + 2H ⎯ M⎯→ + H 2S(g)
Solubility：relating to their Ksp value Soluble in water： • Soluble：NH4 + and alkali metal sulfides • Slightly soluble：MgS，CaS，SrS (BeS poorly soluble) • The other sulfides are poorly soluble Soluble in dilute acid： MnS, FeS, CoS, NiS, ZnS MS + 2H ⎯ M⎯→ + 2+ + H 2S(g)

77 SnS + 2H + 4 Cl ⎯ SnCl + H 2S⎯→ SnS 2 + 4H + 6 Cl ⎯ SnCl + 2H 2S⎯→
Coordination dissolution in acidic solution (e.g.: in concentrated HCl)： → complex ion + y H2S MxSy + 2y + H +z - Cl SnS + 2H + 4 Cl ⎯ SnCl + H 2S⎯→ + − 2- 4 SnS 2 + 4H + 6 Cl ⎯ SnCl + 2H 2S⎯→ + − 2- 6 PbS + 2H + 4 Cl ⎯ PbCl + H 2S⎯→ + − 2- 4 Sb 2S 3 + 6H + 12 Cl ⎯ 2SbCl + 3H 2S⎯→ + − 3- 6 Sb 2S H + 12 Cl ⎯ 2SbCl + 5 H 2S⎯→ + − − 6 Bi 2S 3 + 6H + 8Cl ⎯ 2BiCl + 3H 2S⎯→ + − - 4 CdS + 2H + 4 Cl ⎯ CdCl⎯→ + − 2- 4 + H 2S

78 Soluble in oxidizing acid (HNO3)：
Bi 2 S3 + 8HNO 3 ⎯ 2Bi(NO 3 ) 3 + 2NO + 3S + 4H 2 O⎯→ 3PbS + 8HNO 3 ⎯ 3Pb(NO 3 ) 2 + 2NO + 3S + 4H 2 O⎯→ 3CuS + 8HNO 3 ⎯ 3Cu(NO 3 ) 2 + 2NO + 3S + 4H 2 O⎯→ 3Ag 2 S + 8HNO 3 ⎯ 6AgNO 3 + 2NO + 3S + 4H 2 O⎯→ Oxidization-Coordination dissolution (kingly water)： 3HgS + 2HNO HCl ⎯⎯→ 3H 2 [HgCl 4 ] + 3S + 2NO + 4H 2 O

79 SnS 2 Sb 2 S3 Sb 2 S5 Soluble in base (NaOH or Na2S) As 2 S3 As 2 S5
⎯→2SnS2 + 6OH ⎯ 2SnO + SnS + 3H 2 O - 2- 3 2- 3 SnS 2 SnS2 + S ⎯ SnS⎯→ 2- 2- 3 As 2S3 + 6OH ⎯ AsO + AsS + 3H 2 O⎯→ - 3- 3 3- 3 As 2 S3 As 2S3 + 3S ⎯ 2AsS⎯→ 2- 3- 3 4As 2S5 + 24OH ⎯ 3AsO + 5AsS + 12H 2 O⎯→ - 3- 4 3- 4 As 2 S5 As 2S5 + 3S ⎯ 2AsS⎯→ 2- 3- 4 Sb 2S3 + 6OH ⎯ SbO + SbS + 3H 2 O⎯→ - 3- 3 3- 3 Sb 2 S3 Sb 2S3 + 3S ⎯ 2SbS⎯→ 2- 3- 3 4Sb 2S5 + 24OH ⎯ 3SbO + 5SbS + 12H 2 O⎯→ - 3- 4 3- 4 Sb 2 S5 Sb 2S5 + 3S ⎯ 2SbS⎯→ 2- 3- 4 HgS + S ⎯ [HgS2 ]⎯→ 2- 2-

80 SnS + Na 2 S 2 ⎯ Na 2 SnS 3⎯→ As 2 S3 + 3Na 2 S 2 ⎯ 2Na 3 AsS4 + S⎯→
Oxidization dissolution in basic solution： (e.g.: Na2S2 has oxidizing ability) SnS + Na 2 S 2 ⎯ Na 2 SnS 3⎯→ As 2 S3 + 3Na 2 S 2 ⎯ 2Na 3 AsS4 + S⎯→ Sb 2 S3 + 3Na 2 S 2 ⎯ 2Na 3SbS 4 + S⎯→

81 3FeS 2 + 8O 2 ⎯ Fe 3 O 4 + 6SO 2⎯→ S x=2~6 Na 2 S x , (NH 4 ) 2 S x
2- 3. Polysulfides 2- X S x=2~6 Na 2 S x , (NH 4 ) 2 S x Preparation： Na 2 S + (n - 1)S ⎯⎯→ Na 2 S x phenomena：yellow→orange→red when x↑ Properties： • unstable in acidic condition +2-Sx + 2H → [H 2Sx ] ⎯ H 2S(g) + (x - 1)S⎯→ • oxidizing ability 2-2-SnS + S 2 ⎯ SnS 3⎯→ • weak reducing ability 3FeS 2 + 8O 2 ⎯ Fe 3 O 4 + 6SO 2⎯→

82 Π 4. Sulfur dioxide, sulfurous acid and its salts
The structure of SO2： 2 sp O3 ? 2S：sp hybridization， ∠OSO=119.5°, Π 4 3 bond length of S-O: 143pm， The properties of SO2： SO2 is polar molecule A colorless gas with a pungent odor, it dissolves in water to give solutions of sulfurous acid.

83 • binary medium acid (只存在水溶液中) Ka1 = 1.7×10
Properties of H2SO3： • binary medium acid (只存在水溶液中) H + HSO + Ka1 = 1.7×10 - 3 -2 H 2SO 3 H + SO + Ka2 = 6.0× 10 - 3 2- 3 -8 HSO • oxidization ability H 2 SO 3 + 2H 2 S ⎯ 3S + 3H 2 O⎯→ EA (SO /H 2SO 3 ) = V 2-2- EB (SO 4 /SO 3 ) = −0.9362V • reduction ability 2- 4 H 2 SO 3 + I 2 + H 2 O ⎯ H 2 SO 4 + 2HI (Cl 2 , Br2 )⎯→ 2H 2 SO 3 + O 2 ⎯ 2H 2 SO 4⎯→ - I2 -+2e 2I E =0.5345V

84 Reaction of H2SO3with Br2 (Cl2, I2)
⎯→H 2 SO 3 + I 2 + H 2 O ⎯ H 2 SO 4 + 2HI (Cl 2 , Br2 ) ⎯→ 使品红褪色2H 2 SO 3 O 2 ⎯• bleaching+agent----2H 2 SO 4

85 π 5. Sulfur trioxide, sulfuric acid and its salts
The structure of SO3： S： 3s23p4; O: 2S22P4 S：(special) hybridization： 2pd 2sp 6 4 π ∠OSO=120°, bond length of S-O: 143pm

86 The properties of SO3： γ 型 晶 体 β型晶体
At solid state: colorless, volatile, and are classified to different types of polymer; e.g.: γ-type crystal composed of trimer molecules β-type crystal composed of helical chains γ 型 晶 体 β型晶体

87 solid H2SO4: wave-like layer structure with H-bonds
The structure of H2SO4： d orbits S： 23p4;3s O: 22p42s S: 3sp hybridization，σbonds + (p-d) π反馈配键 3 S：sp 2个O 2个O solid H2SO4: wave-like layer structure with H-bonds

88 C12 H 22 O11 ⎯ 12C + 11H 2 O⎯→ The properties of concentrated H2SO4
−2 • binary strong acid Ka2 = 1.0×10 • strong water adsorbing ability: used as drying agent It can dewater fiber and sugar C12 H 22 O11 ⎯ 12C + 11H 2 O⎯→

89 • strong oxidizing agent
reacts with active metal： Δ 3Zn + 4H 2 SO 4 (浓)3ZnSO 4 + S + 4H2 O Δ4Zn + 5H 2 SO 4 (浓)4ZnSO 4 + H 2 S + 4H2 O reacts with inactive metal： Cu + 2H 2 SO 4 (浓) ⎯ CuSO 4 + 2SO 2 + 2H 2 O⎯→ Δ reacts with metalloid(非金属)： ΔC + 2H 2 SO 4 (浓) ⎯ CO 2 + 2SO 2 + 2H 2 O⎯→ Δ 2P + 5H 2 SO 4 (浓) ⎯ P2 O 5 + 5SO 2 + 5H 2 O⎯→ S + 2H 2 SO 4 (浓) ⎯ 3SO 2 + 2H 2 O⎯→ Δ

90 6. Other sulfur oxyacids and related salts
• Thiosulfuric acid and its salts thiosulfuric acid (H2S2O3)：unstable thiosulfate：Na2S2O3 5H2O，“hypo” (海波)， U2 also called sodium hyposulfite (大苏打) •Preparation： Na 2 SO 3 + S ⎯ Na 2 S 2 O 3⎯→ •Properties： It readily dissolves in water to give a weak basic solution and decomposes in the presence of acids: S2 O + 2H + S + SO 2 + H 2 O 2- 3 H 2S 2 O 3

91 苏打是Soda的音译，化学式为Na2CO3。它的名字颇多，学名叫碳酸钠，俗名除叫苏打外，又称纯碱或苏打粉。带有结晶水的叫水合碳酸钠，有一
幻灯片 82 U2 1.苏打 苏打是Soda的音译，化学式为Na2CO3。它的名字颇多，学名叫碳酸钠，俗名除叫苏打外，又称纯碱或苏打粉。带有结晶水的叫水合碳酸钠，有一 水碳酸钠(Na2CO3·H2O)、七水碳酸钠(Na2CO3·7H2O)和十水碳酸钠(Na2CO3·10H2O)三种。十水碳酸钠又叫洗濯苏打、洗濯碱或晶碱。 无水碳酸钠是白色粉末或细粒，易溶于水，水溶液呈碱性。它有很强的吸湿性，在空气中能吸收水分而结成硬块。十水碳酸钠是无色晶体，室温 下放置空气中，会失去结晶水而成为一水碳酸钠。无论十水碳酸钠还是一水碳酸钠，加热都会变成无水碳酸钠。碳酸钠很稳定，受热不易分解。 遇酸能放出二氧化碳： Na2CO3+2HCl====2NaCl+H2O+CO2↑ 碳酸钠溶液还能吸收二氧化碳而成碳酸氢钠： Na2CO3+H2O+CO2====2NaHCO3 在三种苏打中，碳酸钠的用途最广。它是一种十分重要的化工产品，是玻璃、肥皂、纺织、造纸、制革等工业的重要原料。冶金工业以及净化水 也都用到它。它还可用于其他钠化合物的制造。早在十八世纪，它就和硫酸、盐酸、硝酸、烧碱并列为基础化工原料--三酸两碱之一。在日常生 活中，苏打也有很多用途，比如它可以直接作为洗涤剂使用，在蒸馒头时加一些苏打，可以中和发酵过程中产生的酸性物质。 2.小苏打 小苏打的化学式是NaHCO3。它的名字也有很多，学名碳酸氢钠，又称重碳酸钠或酸式碳 酸钠。俗名除小苏打外，还有焙烧苏打、发酵苏打和重碱等。 小苏打是白色晶体，溶于水，水溶液呈弱碱性。在热空气中，它能缓慢分解，放出一部分二氧化碳；加热至270℃时全部分解放出二氧化碳。 2NaHCO3====Na2CO3+H2O+CO2↑，它也能与酸(如盐酸)作用放出二氧化碳： NaHCO3+HCl====NaCl+H2O+CO2↑ 小苏打的这些性质，使它在生产和生活中有许多重要的用途。在灭火器里，它是产生二氧化碳的原料之一；在食品工业上，它是发酵粉的一种主 要原料；在制造清凉饮料时，它也是常用的一种原料；在医疗上，它是治疗胃酸过多的一种药剂。 3.大苏打 大苏打是硫代硫酸钠的俗名，又叫海波(Hypo的音译)，带有五个结晶水(Na2S2O3·5H2O)，故也叫做五水硫代硫酸钠。 大苏打是无色透明的晶体，易溶于水，水溶液显弱碱性。它在33℃以上的干燥空气中风化而失去结晶水。在中性、碱性溶液中较稳定，在酸性溶 液中会迅速分解。 Na2S2O3+2HCl====2NaCl+H2O+S↓+SO2↑ 大苏打具有很强的络合能力，能跟溴化银形成络合物。反应式：AgBr+2Na2S2O3====NaBr+Na3〔Ag(S2O3)2〕，根据这一性质，它可以作定影剂。 洗相时，过量的大苏打跟底片上未感光部分的溴化银反应，转化为可溶的Na3〔Ag(S2O3)2〕，把AgBr除掉，使显影部分固定下来。 大苏打还具有较强的还原性，能将氯气等物质还原。 Na2S2O3+4Cl2+5H2O====H2SO4+2NaCl+6HCl，所以，它可以作为绵织物漂白后的脱氯剂。类似的道理，织物上的碘渍也可用它除去。 另外，大苏打还用于鞣制皮革、电镀以及由矿石中提取银等。 User,

92 2S2 O + I 2 ⎯ S O + 2I⎯→ O O S O S +I + 2I O S S S O O O O O O S O S
reducing agent： 2S2 O + I 2 ⎯ S O + 2I⎯→ 2- 3 2- 4 6 Tetrathionate - 2- O O O O 2- S S O S O S +I + 2I − I 2- O S S S O O O O S2 O + 4Cl 2 + 5H 2 O ⎯ 2SO + 8Cl + 10H⎯→ 2- 3 2- 4 - + coordination agent： AgBr + 2S2 O → Ag(S2 O ) + Br 2- 3 3- 3 2 -

93 • disulfuric acid and its salts
冷却发烟硫酸时，可以析出焦硫酸晶体 SO 3 + H 2 SO 4 ⎯ H 2 S 2 O 7⎯→ O O H 2 S2 O 7 + H 2 O HO S OH H O S OH OO H2S2O7为无色晶体，吸 水性、腐蚀性比H2SO4更强。 O O S S O OH O O OH Disulfuric acid can be used as solvent α - Al 2 O 3 + 3K 2 S 2 O 7 ⎯ Al 2 (SO 4 ) 3 + 3K 2 SO 4 ⎯→ TiO 2 + K 2 S 2 O 7 ⎯ TiOSO 4 + K 2 SO 4⎯→

94 • peroxysulfuric acid(过硫酸) and its salts hydrogen peroxide：H-O-O-H
OOH磺 O OOO O S 酸 OH基 O OOOH HO peroxo-monosulfuric acid peroxo-disulfuric acid 过二硫酸盐： K 2 S 2 O 8 (NH 4 ) 2 S 2 O 8 E (S2 O8 /SO 4 ) = 1.939Vstrong oxidizing agent： 2- 2- 2− + 2+ + 5S 2 O 8 + 8H 2 O ⎯⎯→⎯ Ag 2Mn 2MnO SO H - 2- + ⎯→poorly stable： 2K 2 S 2 O 8 ⎯ 2K 2 SO 4 + 2SO 3 + O 2 Δ

95 H 2S2 O3 ⎯ S + H 2SO3⎯→ × • dithionous acid 连二亚硫酸：(H2S2O4) OO S S HOOH
sulfurous S S S acid： HOOH HO OH Ka1 = × -1 binary medium acid： Ka2 = 3.5×10 -3 It will decomposes in the presence of water： 2H 2S2 O 4 + H 2 O ⎯ H 2S2 O 3 + 2H 2SO3⎯→ H 2S2 O3 ⎯ S + H 2SO3⎯→

96 2Na2S2O4 ⎯ Na 2S2O3 + Na 2SO3 + SO2⎯→ Na 2S2 O 4 ⋅ 2H 2 O：
Dithionite (连二亚硫酸盐)： Rongalite, Sodium Hydrosulfite(保险粉) Na 2S2 O 4 ⋅ 2H 2 O： 2− reducing agent： E (SO 3 /S 2 O 4 ) = − 1.12V Na 2S2O4 + O2 + H 2O ⎯ NaHSO3 + NaHSO4⎯→ The stability of sodium dithionite is superior than the corresponding acid： 2Na2S2O4 ⎯ Na 2S2O3 + Na 2SO3 + SO2⎯→ Δ

97 ⋅ ⋅ ⋅⋅ 2- O 4 3 O ：Π ：O C 6 4 Π ⋅⋅ ⋅ ⋅ C O O NO2 Π 3 4 3 Π 6 4 Π ?

98 − O O P N HO OH O O OH Π 6 4 6 4 π O O P H HO P H HO H Π 4 3

99 中文教材 pp: 505—507: 2, 8, 9, 10 本章作业(exercises) Textbook in English: