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(b) (i)   E ° M 3 + / M 2 +  values for the first series of transition elements are given below. Answer the question that follows:
 

 
Identify the two strongest oxidising agents in the aqueous solution from the above data.

(ii) Copper(I) ion is not known in aqueous solution.
(iii) The highest oxidation state of a metal is exhibited in its oxide.

Dear studen,
  1. Co and Mn are the two most oxidising agent as greater the reduction potential greater is the tendency to get reduced and oxidise others.
  2. Cu+1 does not exist in aqueous solution. It is because when Cu (I) get hydrated in aqueous solution releasing an enormous amount of heat due to high charge density . The hydration energy is used in the release of one more electron making it a stable Cu2+ ion.
  3. Oxygen is the second most electronegative element. Fluorine is most electronegative but it cannot accommodate electrons due to smaller size. Oxygen can gain electrons and being highly electronegative element causes the other element to loose electrons . Hence most of the metals show highest oxidation state in their oxides.
Regards 

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(ii)In an aqueous medium, Cu2+ is more stable than Cu+. This is because although energy is required to remove one electron from Cu+ to Cu2+, high hydration energy of Cu2+ compensates for it. Therefore, Cu+ ion in an aqueous solution is unstable. It disproportionates to give Cu2+ and Cu.
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(iii)The oxidation state of an element is related to the number of electrons that an atom loses, gains, or appears to use when joining with another atom in compounds. It also determines the ability of an atom to oxidize (to lose electrons) or to reduce (to gain electrons) other atoms or species. Oxidation results in an increase in the oxidation state. Reduction results in a decrease in the oxidation state. If an atom is reduced, it has a higher number of valence shell electrons, and therefore a higher oxidation state, and is a strong oxidant. For example, oxygen (O) and fluorine (F) are very strong oxidants.Both oxide and fluoride ions are highly electronegative and have a very small size. Due to these properties, they are able to oxidize the metal to its highest oxidation state.
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