北京化工大学：《无机化学》课程电子教案（教学课件，2011）Chapter 15 p-block elements（Ⅲ）

Chapter 15 The p-block elements (III) x§15.1 The halogens x*§15.2 The rare gases x 15.3 The property variations for compounds of p-block elements

Chapter 15 The p-block elements ( Ⅲ ) §15.3 The property variations for compounds of p-block elements * §15.2 The rare gases §15.1 The halogens

§15.1 The halogens 15.1.1 The halogens 15.1.2 The elemental substances 15.1.3 Hydrogen halides 15.1.4 Halides and Polyhalides 15.1.5 halogen oxyacids

§15.1 The halogens 15.1.5 halogen oxyacids 15.1.4 Halides and Polyhalides 15.1.3 Hydrogen halides 15.1.2 The elemental substances 15.1.1 The halogens

15.1.1 The halogens Properties of the halogens: Elements(VII) 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 /kJmol-1 1008 Electron affinity -328回 -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 2s 22p5 3s 23p5 4s 24p5 5s 25p 5 configuration Atomic radius/pm 64 99 114 133 Ionization energy /kJ·mol-1 1681 1251 1140 1008 Electronegativity 3.98 2.96 3.16 2.66 Electron affinity energy /kJ·mol-1 -328 -349 -325 -295 Oxidation number - 1 -1 ， 1 ， 3 ， 5 ， 7 15.1.1 The halogens z1

15.1.2 The elemental substances 1.Physical properties of the elemental substances: F2 C12 Br2 State of aggregation g g 1 S Intermolecular force small large b.p./'C -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 F 2 Cl2 Br2 I 2 15.1.2 The elemental substances

2.Chemical properties of the elemental substances ·redox properties F2 C2 Br2 12 EΘ(X2/X)/V:2.8891.3601.0774 0.5345 X2 oxidizing ability:strong weak X reducing ability:weak strong Conclusion: Herein,F2:the strongest oxidant,I:the strongest reductant lo

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

X2 oxidization ability: Example: C2+Br→2C+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)>Cl2(slow under light)>Br(extremely slow) Disproportionation reaction(without base): X,+H,O-HXO+HX Cl2 Br2 I2 Ke(C12)=4.2×10-4 K8(Br2)=7.2×10-9 KeL2)=2.0×10-13 We can see that the major constituent of the solution dissolved with Cl,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X2在H,0中的溶解、歧化

X2 + 2H2O ⎯⎯→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 = × 13 (I2 ) 2.0 10− K = × X2 + H2O HXO + HX F2(vigorous) > Cl2 (slow under light) > Br(extremely slow) I2

Products of disproportionation reaction under basic condition X2+20H→X+X0+HO 30X→2X+X03 3X2+60H→5X+XO3+3H,0 0.7665 BrO 0.5357 0.4556 1.0774 BrO B Br 0.5196

Products of disproportionation reaction under basic condition + ⎯⎯→ + + + ⎯⎯→ + + − − − − − 3X 6OH 5X XO 3H O X 2OH X XO H O 2 3 2 2 2 _ 3OX - → 2X - + XO 3 -

room low heated temperature temperature Cl2 C103 CIO CIO PH>4 Br2 BrO: BrO3BrO(0°C)PH>6 I03 I03 PH>9

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-

3.The preparation of the elemental substances F2(g)electrolysis: The formal reaction:2KHF2 电解)2KF+H2+F + HF The real reaction 2HFFH2 C1,(g)Industry method (electrolysis): 2NaC1+2H,0地解>H2+Cl2+2NaOH √Laboratory method: MnO +4HCH A >MnCl,+Cl(g)+2HO (concentrated)

•Cl2 (g) 2NaCl 2H O H2 Cl2 2NaOH 电解 + 2 ⎯⎯→ + + 9Laboratory method： MnO2 +4HCl⎯⎯→MnCl2+Cl2 (g)+2H2O Δ 9Industry method (electrolysis)： 3. The preparation of the elemental substances ： (concentrated) •F2 (g) electrolysis： 2 2 电解 2KHF2⎯⎯→2KF+H +F + HF The real reaction 2HF → F2 + H2 The formal reaction: electrolysis