What is the oxidation number assigned to manganese in KMnO4? (1) +7 (3) +3 (2) +2 (4) +4
The Correct Answer and Explanation is:
The correct oxidation number of manganese (Mn) in KMnO4 is +7.
Explanation:
To determine the oxidation number of manganese in potassium permanganate (KMnO4), we follow these steps:
- Identify the oxidation states of other elements:
- Potassium (K) is an alkali metal in Group 1, so its oxidation state is +1.
- Oxygen (O) is typically assigned an oxidation state of -2 in most compounds, except in peroxides or superoxides. Since we are dealing with KMnO4, where oxygen is part of the permanganate ion (MnO4^−), each oxygen atom has an oxidation state of -2.
- Set up the equation for the total charge:
The total charge of the permanganate ion (MnO4^−) is -1. In the formula KMnO4, the overall charge of the compound must be neutral, so the oxidation states must balance to zero. The equation for the oxidation states in KMnO4 is: (Oxidation state of K)+(Oxidation state of Mn)+4×(Oxidation state of O)=0(\text{Oxidation state of K}) + (\text{Oxidation state of Mn}) + 4 \times (\text{Oxidation state of O}) = 0(Oxidation state of K)+(Oxidation state of Mn)+4×(Oxidation state of O)=0 Substituting the known values: (+1)+(Oxidation state of Mn)+4×(−2)=0(+1) + (\text{Oxidation state of Mn}) + 4 \times (-2) = 0(+1)+(Oxidation state of Mn)+4×(−2)=0 +1+(Oxidation state of Mn)−8=0+1 + (\text{Oxidation state of Mn}) – 8 = 0+1+(Oxidation state of Mn)−8=0 Oxidation state of Mn−7=0\text{Oxidation state of Mn} – 7 = 0Oxidation state of Mn−7=0 Oxidation state of Mn=+7\text{Oxidation state of Mn} = +7Oxidation state of Mn=+7 - Conclusion:
Therefore, the oxidation number of manganese in KMnO4 is +7. This high oxidation state is typical for manganese in permanganate compounds, where it exhibits a strong oxidizing character.
This oxidation state of +7 is characteristic of the Mn(VII) ion in KMnO4, which is commonly used as an oxidizing agent in various chemical reactions.
