Calculate Oxidation Numbers Video Lessons

Concept: Oxidation Number

# Problem: Assign the correct oxidation number to each species in the redox reaction below:2 MnO2(s) + 8 H+(aq) + 4 OH-(aq) ⇌ 2 Mn2+(aq) + 6 H2O(l) + O2(g)

###### FREE Expert Solution

We’re being asked to determine the oxidation states of each species in the given reaction.

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)

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###### Problem Details

Assign the correct oxidation number to each species in the redox reaction below:

2 MnO2(s) + 8 H+(aq) + 4 OH-(aq) ⇌ 2 Mn2+(aq) + 6 H2O(l) + O2(g)