Q.Describe the general physical properties of aryl diazonium salts -- physical state, solubility, and stability in the solid vs. in solution -- and explain why they are always prepared and used in situ (in cold aqueous solution) rather than isolated as a dry solid for storage.

Arenediazonium salts are colourless to pale-yellow crystalline solids that dissolve readily in cold water, and in that cold aqueous state they persist long enough to be used synthetically. But the SAME salt, once dried to a solid, is markedly less stable -- some diazonium salts (particularly certain perchlorates and related salts) are genuinely hazardous, capable of decomposing violently on shock, friction or mild heating. Because of this combination -- fine in cold solution, dangerous or simply unstable once dry -- diazonium salts are, as a matter of standard laboratory practice, always prepared and immediately used in cold aqueou …

Separate the salt's behaviour in cold solution from its behaviour once dried, and connect the differen …

Describing diazonium salts as simply 'unstable' without distinguishing the cold aqueous state (useable) from th …