Although the chemical formulae of Prussian blue and Turnbull's blue are different yet these are supposed to be identical. How is it justified?

Although the chemical formulae of Prussian blue and Turnbull's blue ar

1.	Although the chemical formulae of Prussian blue and Turnbull's blue are different yet these are supposed to be identical. How is it justified?
Answer» Solution :When a ferric salt reacts with POTASSIUM ferrocyanide, Prusian blue is formed. `4FeCl_(3)+3K_(4)[Fe(CN)_(6)]to Fe_(4)[Fe(CN)_(6)]_(3)+12 KCl`. Turnbull's blue is formed as a deep blue precipitate when a ferrous salt reacts with potassium ferricyanide. `3FeCl_(2)+2K_(3)[Fe(CN)_(6)]toFe_(3)[Fe(CN)_(6)]_(2)+6 KCl`. Other investigations like `X-`ray, have shown that these two compounds Viz., Pussian blue and Turnbull's blue are the same. When either of the reactions given above is performed, a redox reaction also TAKES place partially: `{:(Fe^(3+)+[Fe"(CN)_(6)]^(4-) to Fe^(2+)+[Fe"'(CN)_(6)]^(3-)),(Fe^(2+)+[Fe"'(CN)_(6)]^(3-) to Fe^(3+)+[Fe"(CN)_(6)]^(4-)):}` So, in both the cases, the compounds have a mixture of `Fe^(2+),Fe^(3+),[Fe(CN)_(6)]^(4-)` and `[Fe(CN)_(6)]^(3-)`. Therefore, we WRITE Prussian and Turnbull's blue as `Fe[Fe(CN)_(6)]^(-)`. This can be DUE to `Fe^(2+)` and `[Fe'''(CN)_(6)]^(3-)` or due to `Fe^(3+)` and `[Fe"(CN)_(6)]^(4-)`.