What is the oxidation number of Chromium in Potassium Dichromate (K2Cr2O7)?
Answer and explanation
Correct answer: C. +6
- Step 1: Potassium is +1, Oxygen is -2. Total charge of neutral compound is zero: 2(+1) + 2(Cr) + 7(-2) = 0. Step 2. +2 + 2(Cr) - 14 = 0 => 2(Cr) = 12 => Cr = +6. Answer: +6. Why not the others: +3 is the reduced oxidation state found in Cr^3+ green salts; +7 is the oxidation state of Manganese in KMnO4; +4 is found in Chromium dioxide (CrO2).
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