US EPA - Contaminant Focus - Chromium VI - Chemistry and Behaviour
Description
Elemental chromium (CAS 7440-47-3) is a transition group metal that can have oxidation states ranging from -2 to +6. The most commonly occurring states in chromium compounds are +2, +3, and +6 with the +2 being unstable and readily oxidized to +3. Cr(III) compounds are the most stable form. Chromium metal is not naturally occurring and the presence of Cr(VI) can generally be attributed to industrial activity. Most Cr(III) compounds are only sparingly soluble at the normal range of groundwater pH (5.5-8.0) while some Cr(VI) compounds can be very soluble.
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