Preparation of Chromic Acid Cleaning Solution A simple method for preparing chromic acid cleaning solution eliminates the hazards of excessive reaction heat and produces a powerful cleaning solution ready for use in about 30 seconds. Volumetric elmsware cleaned with this solution eives an excellent meniscus far meekion work. To prepare the solution one standard %pound (2220-m1) battle of technick sulfuric acid is mixed with 25 ml of a saturated aqueous solution of chromium trioxide. The trioxide is very water soluble (about 170 @/I00 ml a t 20°C), forming chromic and dichromie acids. The reaction raises the temperature of the solution about 15' above room temperature. Some of the chromic trioxide will separate out as scarlet needles to form a.reservoir of dichromate ions. RICHARD E. KRAUSE
426
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Journal of Chemical Education
