Q29 / 160 · AP EAMCET 2013 · Chemistry

Which one of the following gives Prussian blue colour?

  • A
    $\mathrm{Fe}_2\left[\mathrm{Fe}(\mathrm{CN})_6\right]$
  • B
    $\mathrm{Na}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]$
  • C
    $\mathrm{Fe}_3\left[\mathrm{Fe}(\mathrm{CN})_6\right]_3$
  • Correct answer
    D
    $\mathrm{Fe}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]_3$

Solution

Ferric salts (such as $\mathrm{FeCl}_3$ ) form Prussian blue (blue ppt or colouration) with potassium ferrocyanide. $$ \begin{array}{r} 4 \mathrm{FeCl}_3+3 \mathrm{~K}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right] \longrightarrow \underset{\substack{\text { Prussian blue } \\ \text { (ferric ferrocyanide) }}}{\mathrm{Fe}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]_3} \\ +12 \mathrm{KCl} \end{array} $$

Hence, the correct answer is option: 'D'.

Relevant Questions