Sodium ferrifluoride, Na3FeF6, is obtained on adding ferric chloride or fluoride to a neutral solution of sodium fluoride. It is formed as a white, crystalline precipitate, which is only sparingly soluble in water. It does not give a red colour with thiocyanates, thus indicating that the iron atom is part of the negative radicle.
The subhydrate, 2Na3FeF6.H2O, has also been obtained.
Sodium fluoride and ferric fluoride yield a eutectic mixture, melting at 892° C. and corresponding in composition to the formula 65 NaF.35FeF3. |