We’re being asked to determine the oxidation state of manganese in MnO4– (permanganate ion).
The rules for oxidation states are as follows:
A. General Rules:
1. For an atom in its elemental form (Zn, Cl2, C(graphite), etc.) O.S. = 0
2. For an ion (Li+, Al3+, etc.) O.S. = charge
B. Specific Rules:
1. Group 1A O.S. = +1
2. Group 2A O.S. = +2
3. Hydrogen O.S. = +1, with nonmetals
O.S. = –1 with metals and boron
4. Fluorine O.S. = –1
5. Oxygen O.S. = –1 in peroxides (X2O2, X = Group 1A)
O.S. = –1/2 in superoxides (XO2, X = Group 1A)
O.S. = –2 in other compounds
6. Group 7A O.S. = –1 (except when bonded to O)
Since MnO4– is neither a peroxide or superoxide, the oxidation state of each oxygen atom is –2.
What is the oxidation number of manganese in MnO 4-?