What is the oxidation number of Cr in Cr₂O₇^2-? A) -12 B) -7 C) -2 D) +6 E) +7

Question

Quizplus · Accepted Answer

Since the overall compound is neutral, the sum of oxidation numbers must equal zero. The oxidation number of sulfur is -2, and there are a total of 27 sulfurs, so the total oxidation number contributed by sulfur is -54. The oxidation number of oxygen is -2, and there is 1 oxygen, so the total oxidation number contributed by oxygen is -2. Therefore, the sum of oxidation numbers of chromium is +56, and since there are 9 chromium atoms in the compound, the oxidation number of Cr is +6.

What Is the Oxidation Number of Cr in Cr2O72-

What Is the Oxidation Number of Cr in Cr₂O₇^2-