離子顏色一問

The colours of ions in water :

1. copper(I) ion - not applicable
Copper(I) ion cannot exist in water. In water, copper(I) ion undergoes disprorportionation (self redox reaction).
2Cu+(aq) → Cu(s) + Cu2+(aq)

2. silver ion - colourless

3. manganese(II) ion - colourless
The colour of Mn2+(aq) should be pale pink. However, in CE level, Mn2+(aq) ion is usually obtained from the reduction of dilute (<0.1 M) acidified KMnO4 solution. Due to the low concentration, the pale pink colour is too pale to be observed, and thus Mn2+(aq) ion appears as colourless.

4. copper(II) ion - blue

5. chromium(III) ion - green