北京化工大学：《无机化学》课程电子教案（课件讲稿，2015）Chapter 17 The halogens

§17 The halogens 17.1 The halogens 17.2 The elemental substances 17.3 Hydrogen halides 17.4 Halides and Polyhalides 17.5 halogen oxyacids

§17 The halogens 17.5 halogen oxyacids 17.4 Halides and Polyhalides 17.3 Hydrogen halides 17.2 The elemental substances 17.1 The halogens

17.1 The halogens Properties of the halogens: Elements(VID) F CI Br I Valence electron 2s22p5 3s23p5 4s24p5 5s25p5 configuration Atomic radius/pm 64 99 114 133 Electronegativity 3.98 3.16 2.96 2.66 Ionization energy 16811251 1140 1008 /kJ.mol-1 Electron affinity -328 -349 -325 -295 energy /kJ.mol-1 Oxidation number -1 1,1,3,5,7

Properties of the halogens： Elements(VII) F Cl Br I Valence electron 2s22p5 3s23p5 4s24p5 5s25p5 configuration Atomic radius/pm 64 99 114 133 Ionization energy /kJ·mol-1 1681 1251 1140 1008 Electronegativity 3.98 3.16 2.96 2.66 Electron affinity energy /kJ·mol-1 -328 -349 -325 -295 Oxidation number -1 -1， 1， 3， 5， 7 17.1 The halogens

17.2 The elemental substances 1.Physical properties of the elemental substances: F2 C12 Br2 12 State of aggregation g g Intermolecular force small large b.p./℃ -188 -34 59 185 m.p./℃ -220 -102 -7 114 Color pale yellow red-brown yellow-green dark red

1.Physical properties of the elemental substances： State of aggregation g g l s b.p./℃ -188 -34 59 185 m.p. /℃ -220 -102 -7 114 Color pale yellow red-brown yellow-green dark red Intermolecular force small large F2 Cl2 Br2 I2 17.2 The elemental substances

2.Chemical properties of the elemental substances ·redox properties F2 C12 Br2 2 Ee(X2X)/V:2.8891.360 1.0774 0.5345 X2 oxidizing ability:strong weak X reducing ability:weak strong Conclusion: Herein,F2:the strongest oxidant,I:the strongest reductant

F2 Cl2 Br2 I2 X2 oxidizing ability： strong weak X - reducing ability: • redox properties Herein, F2 : the strongest oxidant, I- : the strongest reductant 2. Chemical properties of the elemental substances (X 2 /X )/V： 2.889 1.360 1.0774 0.5345 - E Conclusion： weak strong

X,oxidization ability: Example: Cl+Br-2CI+Br2

Cl2+Br- 2Cl-+Br2 X2 oxidization ability： Example:

reacts with water:two types of reactions Oxidization reaction:X,+2H,O->4HX+O, F2(vigorous)>C12(slow under light)>Br2(extremely slow) Disproportionation reaction(without base): X2 +H2O-HXO+HX Cl,Br,>I, Ke(C12)=4.2×104K8(Br2)=7.2×109 Ke(L2)=2.0×10-13 We can see that the major constituent of the solution dissolved with Cl2,Br2 and I,is their elemental substance, respectively..氯水，溴水，碘水的主要成分是单质。 Presence of a base can promote dissolution and dispropor- tionation reaction在碱存在下，促进Xz在H,0中的溶解、歧化

X2  2H2 O 4HXO2 Disproportionation reaction(without base)： 2 2 2 Cl  Br  I We can see that the major constituent of the solution dissolved with Cl2 , Br2 and I2 is their elemental substance, respectively.氯水, 溴水, 碘水的主要成分是单质。 Presence of a base can promote dissolution and dispropor￾tionation reaction 在碱存在下，促进X2在H2O中的溶解、歧化。 • reacts with water：two types of reactions Oxidization reaction： 4 (Cl2 ) 4.2 10- K   9 (Br2 ) 7.2 10- K   1 3 (I2 ) 2.0 10- K   X2  H2 O HXO HX F2 (vigorous) > Cl2 (slow under light) > Br2 (extremely slow) I2

Products of disproportionation reaction of Br2 under basic condition X2+20H→X+X0+H0 3X0→2X+X03 3X2+60H→5X+X03+3H20 0.7665 0.5357 0.4556 1.0774 BrO. BrO B Br 0.5196

Products of disproportionation reaction of Br2 under basic condition         - - - - 3X 6OH- 5X XO 3H O X 2OH X XO H O 2 3 2 2 2 _ 3XO-  2X- + XO3 -

X2+2OH→X+XO+HO 3X2+60H→5X+X03+3H20 room low heated temperature temperature Cl2 C103 CIO CIO PH>4 Br2 BrO; BrO; BrO(O°C)PH>6 12 I03 I0 I03 PH>9 Elemental potential diagram for I2

room temperature heated low temperature I PH  9 2 - 3 IO - 3 IO - 3 IO Br PH  6 2 - BrO3 - BrO3 BrO (0 C) - O Cl2 ClO PH  4 3 - - ClO ClO￾Elemental potential diagram for I2 ?     - 3X2 6OH- 5X XO3 3H2O _     - - - X2 2OH X XO H2O

3.The preparation of the elemental substances F2(g)electrolysis The formal reaction: :2KHF2电)2KF+H,+F HF The real reaction 2HFsF Cl2(g)Industry method (electrolysis): 2NaC1+2H,0电解>H2+CL,+2NaOH √Laboratory method: MnO,+4HCI-A >MnCl2+Cl2 (g)+2H2O (concentrated)

•Cl2 (g) 2NaCl 2H O H2 Cl2 2NaOH 电解  2    Laboratory method： MnO2  4HCl MnCl 2 Cl2 (g)  2H2 O  Industry method (electrolysis)： 3. The preparation of the elemental substances ： (concentrated) •F2 (g) electrolysis： 2 2 电解 2KHF 2 2KF H  F + HF The real reaction 2HF  F2 + H2 The formal reaction: electrolysis

氧化电位水是绿色消毒剂 来源于水回归于水 软化的自来水加入 0.05%的氯化钠通过电 解在阳极侧生成氯气， 氯气与水反应生成盐 酸和次氯酸等物质。 另外，水也在阳极侧 酸性水 碱性水 电解，变成氧气和氢 离子，使阳极产生的 液体pH下降到3以下， 氧化还原电位上升到 水 ,0 阴极 水 阳极 1100mV以上，有效氯 浓度达到30~80mg/L NaCl 隔膜 NaCl

氧化电位水是绿色消毒剂 来源于水 回归于水 V ` 酸性水 碱性水 隔膜 水 水 NaCl NaCl Na ＋ 阳极 阴极 H2O OH￾H+ Cl￾Cl2 H2O H+ O2 + - 软化的自来水加入 0.05%的氯化钠通过电 解在阳极侧生成氯气， 氯气与水反应生成盐 酸和次氯酸等物质。 另外，水也在阳极侧 电解，变成氧气和氢 离子，使阳极产生的 液体pH下降到3以下， 氧化还原电位上升到 1100mV以上，有效氯 浓度达到30~80mg/L