(NH4)2S2O8+2KHSO4=K2S2O8 +2NH4HSO4 K2S2O8+ Ho 2KHSO4+ H2O2 Oxidizing properties S208+2e= 2SO4 H 2Mn2+5S2O32+8H2O 2MnO+10SO42+16H 2I+S20%2 Ag 2+2SO2 Thermal instability 2K2S2O8 △→>2K2So4+ O21↑+2SO3↑ Chapter Three Halogens Central Contents 1. Know preparation methods and general properties of halogens 2. Understand the reducing properties, acidity, stability and trends of halogen acids 3. Understand the properties of halides( bond type and solubility)and their trends 4. Understand oxyacids and oxysalts of chlorine and their trend 5. Know the disproportionation law of X2, XO in basic medium 6. Know the ionization of hydrates(R-0-H rule) 7. Know how to identify of Cl, Br and I Section One general Properties of halogens Halogens: Fluorine chlorine bromine . iodine astatine 1. Natural occurring forms 1) F CaF2(fluorite),Na3AlF6(cryolite) 2) Cl, Br, I: Exist in seawater(inorganic salt: Na, K, Ca, Mg) 3) At: Unstable(radioactive) 2. General properties 1)Valence shell configuration ns" n 第21页 2006-02-22第 21 页 2006-02-22 21 (NH4)2S2O8+2KHSO4=K2S2O8 +2NH4HSO4 K2S2O8 + H2O 2KHSO4 + H2O2 Oxidizing properties: S2O8 2- + 2e = 2SO4 2- Eθ =1.96v 2Mn2++5S2O8 2-+8H2O 2MnO4 - +10SO4 2-+16H+ 2I- + S2O8 2- I2 + 2SO4 2- Thermal instability: 2K2S2O8 →Δ 2K2SO4 + O2↑+2SO3↑ Chapter Three Halogens Central Contents: 1. Know preparation methods and general properties of halogens 2.Understand the reducing properties, acidity, stability and trends of halogen acids 3. Understand the properties of halides (bond type and solubility) and their trends 4. Understand oxyacids and oxysalts of chlorine and their trends 5. Know the disproportionation law of X2, XO- in basic medium 6. Know the ionization of hydrates (R-O-H rule) 7. Know how to identify of Cl- , Br- and I- Section One General Properties of Halogens Halogens: Fluorine, chlorine, bromine, iodine, astatine 1.Natural occurring forms 1) F:CaF2(fluorite),Na3AlF6(cryolite) 2) Cl, Br, I: Exist in seawater (inorganic salt: Na, K, Ca, Mg) 3) At: Unstable (radioactive) 2. General properties 1) Valence shell configuration:ns2 np5 H+ Ag+