InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
(i) Name the element of 3d transition series which shows maximum number of oxidation states. Why does it show so ? (ii)Which transition metal of 3d series ha positive `E^(@)(M^(2+)//M)` value and why ? (iii) Out of `Cr^(3+) and Mn^(3+)`, which is a stronger oxidizing agent and why ? (iv) Name a member of the lanthanoid series which is well known to exhibit + 2 oxidation state. (v) Complete the following equation : `MnO_(4)^(-) + 8H^(+) + 5e^(-) to ` . |
|
Answer» In 3d -series of transition metals, manganese has an atomic number of 25 that gives tha electronic configuration as `[Ar] 3d 4s2,` where we see that the maximum number of ltbr. Unpaired electrons is found in manganese atom, so, it can show a maximum oxidation state upto + 7. (ii) Copper is the transition metal of 3d series that exhibits positive `MnO_(4)^(-) + 8H^(+) + 5e^(-) to ` value of a metal depends on the energy changes involved in the following : 1. Sublimation energy : The energy required for converting one mole of an atom from Solid state to the gaseous state. `M_(g) to underset("Sublimation energy")(M_((g)) Delta s H = high` 2. Ionisation energy : The energy required to take out electons from one mole of atom in the isolated gaseous state. `M_((g)) to M_((g)) DeltaH = high` ("Ionisation energy") 3. Hydration energy : The energy released when one mole of ions are hydrated . `M_((g)) to M_((g)) Delta s H ("low energy") ("Hydration energy") ` Since, copper has a high energy of atomisation and low hydration energy, the `E(@) (M^(2+)//M)` value for copper is positive. (iii) Out of `Cr^(3+) and Mn^(3+), Mn^(3+)` is a stronger oxidising agent because it has 4 electrons in its valence shell and when it gains one electron to form `Mn^(2+)`, it results in the half-filled `(d^(5))` configuration that has extra stabillity. (iv) Europium (Eu) is well-known to echibit + 2 oxidation state due to its half filled forbital in + 2 oxidation state. (v) `MnO_(4)^(-)+8H^(+)+ 5e to Mn^(2+) + 4H_(2)O` |
|