Aluminium nitrate cannot be synthesized by the reaction of aluminium with concentrated nitric acid, as the aluminium forms apassivationlayer.
Aluminium nitrate may instead be prepared by the reaction ofnitric acidwithaluminium(III) chloride.Nitrosyl chlorideis produced as a by-product; it bubbles out of the solution as a gas. More conveniently, the salt can be made by reactingnitric acidwithaluminium hydroxide.