Ferric is a term used for the iron with the oxidation number +3. General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... The oxidation state or oxidation number is defined as the sum of negative and positive charges in an atom, which indirectly indicates the number of electrons it has accepted or donated. ...
The salt, ferric chloride, has none of the disadvantages associated with the other two etching solutions: it does not produce dangerous fumes, is odourless and, though corrosive, is not absorbed through the skin.
Ferric chloride solutions in water are strongly acidic but in their reaction with copper no significant fumes or gases are produced.
Ferric chloride can be obtained either as a solid (not recommended as it can give off highly toxic hydrogen chloride fumes when mixed with water) or in liquid form which is usually supplied in a strength of 45° Baume.
A ferric and acid complex as set forth in claim 2 wherein said ferric salt is selected from the group of ferric sulfate, ferric carbonate, ferric chloride, ferric nitrate, ferric bromide, ferric citrate, ferric glycolate, hydrates of said ferric salts, and combinations thereof.
Although the ferric and acid complex may be stored and packaged in the solvent, it is to be appreciated that the ferric and acid complex may be separated from the solvent into a solid form, such as a powder.
Ferric and acid complexes of the subject invention are prepared by first charging solvent into a 1 liter vessel, which is a flask, at room temperature of about 77° F. The chelant is then charged into the vessel, along with a portion of the base until the pH value within the vessel is about 4.
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