Question

For $ZnO$ in \[C{H_3}COOH\] gives bluish white ppt. with X, X is
A.\[\]\[{K_4}[Fe{\left( {CN} \right)_6}]\]
B.\[{K_3}[Fe{\left( {CN} \right)_6}]\]
C.\[N{a_2}[Fe{(CN)_5}NO]\]
D.\[\;Fe{(CO)_5}\;\]

Answer 1

Hint:$ZnO$ is white powder insoluble in water. Zinc Oxide in acetic acid used in creating or making of thin films (containing blue color or considered as blue printing). Ferro-cyanide is not a good reagent.

Complete step by step answer:
So if we see all the given options they have different reactance with $ZnO$ and \[C{H_3}COOH\] as explained below:
\[{K_4}[Fe{\left( {CN} \right)_6}]\] Known as Potassium Ferro-cyanide is potassium salt of the coordination complex (central atom usually metallic)\[{[Fe{\left( {CN} \right)_6}]^{4 - }}\]. It contains tetravalent anion. When reacted with $ZnO$ in \[C{H_3}COOH\] result in release or give bluish precipitates. Also since Potassium Ferro-cyanide is not considered as a good reagent because many metal ions form Potassium Ferro-cyanide precipitates.
On the other hand if we consider \[{K_4}[Fe{\left( {CN} \right)_6}]\]known as Potassium Ferric-cyanide contains octahedrally coordinated (compound with six atoms aligned to central atom) \[{\left[ {Fe{{\left( {CN} \right)}_6}} \right]^{3 - }}\]and it contain trivalent anion. To use it in blue printing first it should be converted to Potassium Ferro-cyanide then it will give bluish precipitates.
\[N{a_2}[Fe{(CN)_5}NO]\] Known as Sodium Nitroprusside is prepared from Potassium Ferro-cyanide in water with nitric acid. So, when it is reacted with zinc oxide in acetic acid it gives purple color.
\[\;Fe{(CO)_5}\;\]Known as iron carbonyl helps catalyst ($ZnO$) in promoting acetic acid to synthesis from different chemical compounds.
So now if we see all above explanations we will conclude that Potassium Ferro-cyanide not only results in precipitation but also that precipitation is in color of bluish white with acetic acid.
So the correct option is (A) \[{K_4}[Fe{\left( {CN} \right)_6}]\].
So, the correct option is B that is $75$.

Additional Information:
Potassium Ferro-cyanide has molecular weight of \[368.35\;g/mol\]and density is $1.58g/c{m^3}$.If we see and look the structure of Potassium Ferro-cyanide, both way as hydrate and anhydrous salts, it has complicated polymeric structure. It consist octahedral \[{[Fe{\left( {CN} \right)_6}]^{4 - }}\] centers cross linked with \[\;{K^ + }\] ions bound to $CN$. The \[\;{K^ + } - - NC\] link breaks when solid is dissolved in water.

Note:
The main thing we should remember about Potassium Ferro-cyanide is that it is not a good reagent. It will definitely release precipitates because of different metal ions. And the precipitation color will be bluish white when reacted with Zinc Oxide in acetic acid. Mostly the precipitation color depends on the substance which is reacted with Potassium Ferro-cyanide.