Ions, colour

Transition metal Modern raw material Colouring ion Colour in tetrahedral coordination (network former) Colour in octahedral coordination (network modifier)... 

Chemists use a range of techniques for qualitative analysis. For example, the colour of an aqueous solution can help to identify one of the ions that it contains. Examine Table 9.3. However, the intensity of ion colour varies with its concentration in the solution. Also keep in mind that many ions are colourless in aqueous solution. For example, the cations of elements from Groups 1 (IA) and 2 (IIA), as well as aluminum, zinc, and most anions, are colourless. So there are limits to the inferences you can make if you rely on solution colour alone. 

Fig. 5.23 (a) One representation of a unit cell of perovskite (CaTiOs) (b) the Ca ion is 12-coordinate with respect to the ions. Colour code Ca, purple O, red Ti, pale grey. 

Metal ion Colour Ground state electronic configuration Ground state term symbol Magnetic moment, p (298 K) / p Calculated Observed ... 

Acids Carboxylic acids (of white wine) Anion exchange chromatography specific hy-droxamate-ferric ion colour detection Kasai et al. [192]... 

Ion " Colour Addition of NaOH(aq) Excess NaOH(aq) Addition of NHjfaq) Excess NH,(aq)... 

Trivalent lanthanide ion Colour of visible luminescence Intensity of the emission... 

Fig. 13.25 The structure of [In(18-crown-6)][CF3S03] 9 determined by X-ray diffraction [C.G. Andrews et al. (2005) Angew. Chem. Int. Ed., vol. 44, p. 7453] the space-filling representation illustrates the embedding of the In(I) centre within the crown ether, and the interaction between the In and [CF3SO3P ions. Colour code In, blue O, red C, grey S, yellow F, green.

Vj Fig. 19.16 The solid state structure (determined by X-ray diffraction) of K2[Ge2H2 C6H3-2,6-(C6H3-2,6- Pr2)2 2] with H atoms omitted except for those attached to the Ge atoms [A.F. Richards et al. (2004) J. Am. Chem. Soc., vol. 126, p. 10530]. Hashed lines highlight the stabilizing influence of the ions. Colour code Ge, orange K, blue C, grey H, white. 

The electro-coagulation process is based on valid scientific principles involving responses of water contaminants to strong electric fields and electrically induced oxidation and reduction reactions. This process is able to take out over 99 percent of some heavy metal cations and also appears to be able to electrocute microorganisms in the water. It is also able to precipitate charged colloids and remove significant amoimts of other ions, colour, colloids and emulsions. 

Oxidation number Formula of aqueous ion Colour of aqueous ion... 

The formation of negatively charged complex ions can be detected using electrophoresis and electrodialysis. In both these processes, the charged species are forced to move by application of external electric field. While the electrophoresis is appHcable to dispersed particles with a surface charge, electrodialysis is used to transport the ions in the solution. The reversed movement of complexed metal ion (coloured ion) toward the positive electrode instead of negative electrode serves as an indicative of complex formation. 

Halide ion Colour of silver halide precipitate on addition of silver nitrate solution Effect on precipitate of adding dilute ammonia solution Effect on precipitate of adding concentrated ammonia solution... 

---