Question

Turnbull’s blue is $F{e_3}{[Fe{(CN)_6}]_2}$?
A. True
B. False

Answer 1

Hint: Turnbull's blue is chemically similar, but made from different reagents, and its slightly different color stems from various impurities.

Complete step by step answer:
-Prussian blue was the first modern synthetic pigment. It is prepared as a very fine colloidal dispersion, as the compound is not soluble in water. It contains variable amounts of other ions and its presence sensitively depends on the size of the colloidal particles. Pigment is used in paint, and is a traditional "blue" and Ezuri-e Japanese woodblock print in blueprint.
-Pigment replaced the expensive lapis lazuli and was an important topic in letters exchanged between $1708$ and $1716$ between Johann Leonhard Frisk and the president of the Prussian -Academy of Sciences, Gottfried Wilhelm Leibniz. It is first mentioned in a letter written by Frisk to Leibinz from $31$ March $1708$. No later than, frisk began promoting and selling pigments across Europe.
-Earlier, in addition to iron (II) salts, a solution of ferricyanide was thought to afford a material different from Prussian blue. The product was traditionally named Turnbull Blue (TB). X-ray diffraction and electron diffraction methods have shown, however, that the structures of PB and TB are similar.
-The color differences for TB and PB reflect subtle differences in precipitation methods, which strongly affect particle size and impurity content.
-${[Fe{(CN)_6}]^{4 - }} + F{e^{3 + }}$ ---(Prussian blue)
${[Fe{(CN)_6}]^{3 - }}F{e_{}}^{2 + }$ $ \geqslant F{e_3}{[Fe{(CN)_6}]^2}$

Note: Ferric ferrocyanide, also known as iron blue, is a synthetic dark blue pigment. Ferric ferrocyanide is used as a coloring agent in cosmetics, including its use around the eyes. Ferric ferrocyanide is generally considered safe.