Question

Write the chemical formula for potassium ferrocyanide.

Answer 1

The symbol of potassium (Kalium) is ‘$\mathrm{K}$’, having a valency of 1⁺.

The formula of ferrocyanide is $‘\mathrm{Fe}{\left(\mathrm{CN}\right)}_6$’ with valency 4^-.

Step 1 –Write the formula of potassium ferrocyanide:

Symbol Valency

Potassium $\mathrm{Fe}$ 1⁺

Ferrocyanide $\mathrm{S}$ 4^-

Step 2 –Write each symbol with its valency:

$\mathrm{K}$ $‘\mathrm{Fe}{\left(\mathrm{CN}\right)}_6$

Step 3 –Interchanging the valencies:

$$\begin{gathered} \mathrm{K}\mathrm{Fe}{\left(\mathrm{CN}\right)}_6 \\ \searrow \swarrow \\ {1}^{+}{4}^{-} \end{gathered}$$

The chemical formula of the compound potassium ferrocyanide would be ${\mathrm{K}}_4\left[\mathrm{Fe}{\left(\mathrm{CN}\right)}_6\right]$.