文档介绍：Halogen
Verify the physical and chemical properties of halogen, haloid oxyacid, haloid oxysalt and hydrogen halide.
Master the methods of how to prepare halogen.
Learn how to identify the halogen ions.
★ Purpose:
1. I2 reacts with metallic and nonmetallic elements
I2 (liquid)+ Zn = ZnI2
2P + 3I2(solid) + 6H2O = 2H3PO3 + 6HCl
2. Compare the oxidation ability of X2
2KI + Cl2 = 2KCl + I2
I2 + 5Cl2 + 6H2O = 2HIO3+ 6HCl
2KI + Br2 = 2KBr + I2
2KBr + Cl2 = 2KBr + I2
★ Procedures:
3. Preparation of the halogens
MnO2 + 2KCl + 2H2SO4 = MnSO4 + Cl2 + K2SO4 + 2H2O 观察淀粉KI试纸颜色
MnO2 + 2KBr + 2H2SO4 = MnSO4 + Br2 + K2SO4 + 2H2O
MnO2 + 2KI + 2H2SO4 = MnSO4 + I2 + K2SO4 + 2H2O
4. Compare the reducing activity of HX
KCl + H2SO4 (conc.) = 2KHSO4 + HCl 观察蓝色石蕊试纸颜色
2KBr + 3H2SO4 (conc.) = 2KHSO4 + Br2 + SO2 + 2H2O 观察I2试液试纸颜色
8KI + 9H2SO4 (conc.) = 8KHSO4 + 4I2 + H2S + 4H2O 观察Pb(Ac)2试纸颜色
SO2 + I2 + 2H2O =H2SO4 + 2HI
H2S + Pb(Ac)2 =PbS↓(黑色)+ 2HAc
5. *Test the oxidizability of hypochlorites and chlorates
2KI + NaClO + H2O = I2 + NaCl + 2KOH
5NaClO + I2 + 2NaOH = 2NaIO3 + 5NaCl + H2O
2KClO3 + 6KI + 3H2SO4 = 3I2 + KCl + 3KSO4 + 3H2O
观察氯仿层颜色
6. *Separation and detection of Cl-, Br-, and I-.
① add 6M HNO3 to acidify the solution.
② add AgNO3 until pletely.
③ separate AgX by centrifugal machine.
Solution (discard)
① wash AgX with distilled water.
② add 12% (NH4)2CO3 2m