Wackenroder solution
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Wackenroder solution is water solution of polythionic acids H2SnO6 (n = 3-20). It is formed by the reaction of hydrogen sulfide (H2S) with sulfur dioxide (SO2) in highly dilute aqueous solution. At temperatures above 20 °C solutes slowly decomposes with separation unit sulfur, sulfur dioxide, and sulfuric acid.[citation needed]