Why can dilute solutions of hydrogen peroxide not be concentrated by heating? How can a conentrated solution of hydrogen peroxide be obtanied ?

Explanation

A dilute solution of hydrogen peroxide is not conentrated upon heating because it decomposes at a temperature at a temperature below its boiling point.
`2H_(2)O_(2)(l) to 2H_(2)O(l)+O_(2)(g)`
Therefore, it has to be concentrated very carefully. For details, consult section 9.11.