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Question: What is the oxidation number of manganese in \( Mn{{O}^{4-}},M{{n}_{2}}{{O}_{3}} \) and \( Mn{{O}_{2...

What is the oxidation number of manganese in MnO4,Mn2O3Mn{{O}^{4-}},M{{n}_{2}}{{O}_{3}} and MnO2Mn{{O}_{2}} ?

Explanation

Solution

Hint : We know that the oxidation state is also known as the oxidation number. The oxidation state can be found out by equating the oxidation number of each molecule by the overall charge of the complex. The oxidation number may be negative zero or positive.

Complete Step By Step Answer:
If the molecule loses an electron, it means it lost a negative charge then the molecule becomes positively charged. If the molecule gains an electron, which means it gained a negative charge hence the molecule becomes negatively charged. The oxidation number is the number of electrons lost or gained from a molecule in order to form a chemical bond with another molecule. Therefore, to find the oxidation state of manganese in MnO4Mn{{O}^{4-}} firstly we will consider the oxidation number on MnMn to be x.x.
As we can see, there is an overall charge of  1~-1 in the given ion therefore the total sum of the oxidation number of all the elements present will be equal to 1.-1. Charge on a single oxygen atom is 2.-2. Therefore, we can write that;
x+[4×(2)]=1x+\left[ 4\times \left( -2 \right) \right]=-1
x=1+8=+7\therefore x=-1+8=+7 , the MnMn in is in a +7+7 oxidation state.
The same strategy applies, only this time you're dealing with a neutral compound, which means that the oxidation numbers of all the atoms must add up to give zero. This means that you have - keep in mind that you get two manganese atoms and three oxygen atoms in manganese (III)\left( III \right) oxide.
[(2×ONMn)+(3×ONoxygen)]=0\left[ \left( 2\times O{{N}_{Mn}} \right)+\left( 3\times O{{N}_{oxygen}} \right) \right]=0
(2×ONMn)=0(3×ONoxygen)\Rightarrow \left( 2\times O{{N}_{Mn}} \right)=0-\left( 3\times O{{N}_{oxygen}} \right)
ONMn=03×(2)2=62=3O{{N}_{Mn}}=\dfrac{0-3\times \left( -2 \right)}{2}=\dfrac{6}{2}=3
Manganese has a (+3) \left( +3 \right)~ oxidation state in manganese (III)\left( III \right) oxide. Notice that the compound's name illustrates that the Roman numeral (III) tells you what the oxidation state of manganese is.

Note :
It is important to remember the charge on atoms in order to find out the oxidation state. Like, the charge of oxygen is 2-2 and that for hydrogen is +1+1 generally but when oxygen is bonded to a more electronegative element it is +2+2 and when hydrogen is bonded with less electronegative element charge is  1.~-1.