Green death

The chemical composition of the green death solution allows it to achieve a particularly aggressive oxidizing chloride solution.^[1] Indeed, among the four reagents, all are oxidizing species (H₂SO₄, Fe³⁺, Cu²⁺) except hydrochloric acid (HCl) in which the chlorine atom is present in its lowest oxidation state as Cl⁻ anion. The chloride anions, also added to the solution as counter-ions of iron(III) and copper(II) species, are very aggressive for the localized corrosion of metals and alloys as they induce severe pitting corrosion problems. The green death solution is also used to determine the critical pitting temperature (CPT) and the critical crevice temperature (CCT) of metals and alloys.^{[citation needed]}

• Aqua regia – Mixture of nitric acid and hydrochloric acid in a 1:3 molar ratio
• Piranha solution – Oxidizing acid mixture containing sulfuric acid and hydrogen peroxide