What is the oxidation number of the chromium in [Cr(H₂O)₂Cl₄]−?

Question

Quizplus · Accepted Answer

The complex ion given is [Cr(H2O)5Cl]−. In this complex, water molecules are neutral ligands and do not contribute to the oxidation state of chromium. The chloride ion (Cl−) contributes -1 to the oxidation state. Since the overall charge of the complex ion is -1 and knowing that the sum of oxidation states in a compound equals the overall charge, the oxidation state of chromium must balance the charges contributed by the ligands and the overall charge. Therefore, the oxidation state of chromium is +3 to balance the -1 from the chloride ion and the -1 overall charge, making the total charge zero when considering the +3 from chromium.

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What Is the Oxidation Number of the Chromium in [Cr(H₂O)₂Cl₄]−