Question

Why can the dilute solution of hydrogen peroxide not be concentrated by heating?

Answer 1

Chemical compounds can be diluted by adding water. By simply heating the diluted compounds, water can be lost and can be concentrated. But some compounds like hydrogen peroxide cannot be concentrated by heating due to unstable peroxy linkage.

Complete answer:
Some of the strong acids like hydrochloric acid, nitric acid are diluted as the concentrated acids are dangerous. When water is added to these acids, then these acids are known as diluted acids.
So many other chemical compounds can be diluted like hydrogen peroxide.
Hydrogen peroxide is a chemical compound with the molecular formula of ${H_2}{O_2}$ , it has two oxygen atoms and two hydrogen atoms. There are a total of $3$ covalent bonds between two oxygens and two hydrogen atoms in hydrogen peroxide. The bond between the two oxygen atoms is known as peroxy bond $\left( {O - O} \right)$ . This bond is an unstable bond.
When hydrogen peroxide is heated, the bond between the oxygen and oxygen cleaves results in the formation of water and oxygen radicals.
By simply heating the chemical compounds, the water present in them will be evaporated and concentrated. But hydrogen peroxide is a different case.
Thus, a dilute solution of hydrogen peroxide is heated, it cannot be concentrated but forms water and oxygen radicals.

Note:
Hydrogen peroxide is a chemical compound that belongs to the peroxide family. Peroxide bond is a bond between two oxygen atoms, it is an unstable and weak bond that can be cleavaged easily upon heating.