Question

The chemical formula of magnet…..?

Answer 1

The chemical formula of the magnet is ${\mathrm{Fe}}_3{\mathrm{O}}_4$

The iron oxide with the chemical formula ${\mathrm{Fe}}_3{\mathrm{O}}_4$is known as the mineral magnetite. This iron oxide is encountered in the laboratory as a black powder. It exhibits permanent magnetism and is ferrimagnetic. It is one of a no. of iron oxides, the other being iron(2) oxide(FeO), which is rare, and iron(3) oxide$\left({\mathrm{Fe}}_2{\mathrm{O}}_3\right)$ which also occurs naturally as mineral hematite.

Although magnetite can be extracted naturally but due to its laboratory use where it is needed in different shapes it also synthesizes in a laboratory.

Preparation of magnetite:

Under anaerobic conditions, ferrous hydroxide$\left[\mathrm{Fe}{\left(\mathrm{OH}\right)}_2\right]$ can be oxidised by water to form magnetite and molecular hydrogen. This process is described by the Schikorr reaction.

$$\begin{gathered} 3\mathrm{Fe}{\left(\mathrm{OH}\right)}_2\to {\mathrm{Fe}}_2{\mathrm{O}}_4+{\mathrm{H}}_2+2{\mathrm{H}}_2\mathrm{O} \\ \mathrm{ferrous}\mathrm{hydroxide}\mathrm{magnetite} \end{gathered}$$

The well-crystallized magnetite (Fe₃O₄) is thermodynamically more stable than the ferrous hydroxide (Fe(OH)₂).