Hydrazoic acid was originally prepared by the reaction of aqueous hydrazine with nitrous acid. Other oxidizing agents, such as hydrogen peroxide, nitrosyl chloride, trichloramine or nitric acid, can also be used. In its properties hydrazoic acid shows some analogy to the halogen acids, since it forms poorly soluble (in water) lead, silver and mercury(I) salts. The metallic salts all crystallize in the anhydrous form and decompose on heating, leaving a residue of the pure metal. It is a weak acid (p"K" = 4.75.) Its heavy metal salts are explosive and readily interact with the alkyl iodides. Azides of heavier alkali metals (excluding
Metal Gear Acid vecuronium bromide, the chemical used by Elsie and Frances to hijack Flight 326. The third is stated to be an acronym for Active Command Intelligence Duel, a reference to the game's mixture of turn-based tactics with card-based gameplay. The game's soundtrack was composed by Nobuko Toda, Shuichi Kobori and Akihiro Honda. The soundtrack was released on December 21, 2005, packaged with the "Metal Gear Acid 2" soundtrack. The album's title is "Metal Gear Acid 1 and 2 Original Soundtrack". "Metal Gear Acid" received generally positive reviews from critics. "Acid" was followed by a sequel for the PSP, "Metal Gear Acid