why diazonium salt affected by heat?

Answer 1

When the N3 decomposed it liberates N2 and N2 is the worlds best leaving group therefore making the azide functional group unstable. I new a person when I was in grad school who made an azide. It was in solution in a flask in the freezer and when the student removed it from the freezer and placed it on the lab bench it blew up. It blew off all their fingers.

Answer 2

They are very unstable