Potassium cyanide is made alkaline with NaOH and boiled with thiosulphate ions. The solution is cooled and acidified with HCl and this solution with iron ( III ) chloride produces :-

Question

Aicharya · Accepted Answer

The reaction of potassium cyanide with sodium hydroxide gives the cyanide ion. After that cyanide ion reacts with the thiosulphate ions and cool and acidify in presence of the hydrochloric acid. It gives the thiocyanide ion.

$KCN + NaOH \to NaCN + KOH$

$S_{2} {O_{3}}^{2 -} + {CN}^{-} \overset{HCl}{\to} {SCN}^{-} + {SO}_{3}^{-}$

The thiocyanate ion reacts with the iron $(III)$ chloride and formed the $Fe {(SCN)}^{2 +}$ and the complex has the blood-red colour.

${FeCl}_{3} + {SCN}^{-} \to Fe {(SCN)}^{2 +} (blood red colour)$

Hence, the solution is cooled and acidified with

HCl

and this solution with iron

(III)

chloride produces blood-red colour solution.

Potassium cyanide is made alkaline with NaOH and boiled with thiosulphate ions. The solution is cooled and…

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