Chlorine ,Bromine and iodine

2007-10-23 5:09 pm

請問有什麼簡易的實驗方法可分辨 Cl -, Br- and I- ( 除了加入AgNO3 ) ?
令外, what is the reaction ( in equation) of dilute nitric acid is added into Cl- (aq), Br- (aq) and I- (aq) respectively ?

回答 (1)

魏王將張遼

2007-10-23 6:44 pm

✔ 最佳答案

可用 acidified potassium permanganate solution, 其 observation 如下:
Cl-: A greenish-yellow gas is evolved
10Cl-(aq) + 2MnO4-(aq) + 16H+(aq) → 5Cl2(g) + 2Mn2+(aq) + 8H2O(l)
Br-: The solution turns reddish-brown in colour or a reddish-brown gas is evolved
10Br-(aq) + 2MnO4-(aq) + 16H+(aq) → 5Br2(g) + 2Mn2+(aq) + 8H2O(l)
I-: The solution turns dark brown in colour
10I-(aq) + 2MnO4-(aq) + 16H+(aq) → 5I2(s) + 2Mn2+(aq) + 8H2O(l)
I-(aq) + I2(s) → I3-(aq) (dark brown complex)
The reaction between dilute nitric acid and halide ions is as follows:
6X-(g/s) + 2NO3-(aq) + 8H+(aq) → 3X2(g/s) + 2NO(g) + 4H2O(l)
Note: X = Cl, Br or I and state symbol = g for Cl/Br and s for I

參考: My chemical knowledge

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