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प्रश्न
Following are the transition metal ions of 3d series:
Ti4+, V2+, Mn3+, Cr3+
(Atomic numbers: Ti = 22, V = 23, Mn = 25, Cr = 24)
Answer the following:
1) Which ion is most stable in an aqueous solution and why?
2) Which ion is a strong oxidising agent and why?
3) Which ion is colourless and why?
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उत्तर
1)
| Gaseous ions | Number of unpaired electrons |
| Ti4+, [Ar] 3d0 | 0 |
| V2+, [Ar] 3d3 | 3 |
| Mn3+, [Ar] 3d4 | 4 |
| Cr3+, [Ar] 3d3 | 3 |
V2+ and Cr3+ are the most stable ions in aqueous solutions owing to `t_(2g)^3` a configuration.
2) An examination of the Eo values for the redox couple M3+/M2+ (from electrode potential table) shows that Mn3+ ion are the strongest oxidising agents in aqueous solutions.
3) Only the ions that have electrons in d-orbital and in which d-d transition is possible will be coloured. The ions in which d-orbitals are empty or completely filled will be colourless as no d-d transition is possible in those configurations.
From the given transition metal ions, it can be easily observed that only Ti4+ has an empty d-orbital, so, it is colourless ion.
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संबंधित प्रश्न
Complete the following chemical equations:
`(i) Cr_2O_7^(2-)+6Fe^(2+)+14H^+ ->`
`(ii) 2CrO_4^(2-)+2H^+ ->`
`(iii) 2MnO_4^-+5C_2O_4^(2-)+16H^+ ->`
For M2+/M and M3+/M2+ systems, the EΘ values for some metals are as follows:
| Cr2+/Cr | −0.9 V |
| Mn2+/Mn | −1.2 V |
| Fe2+/Fe | −0.4 V |
| Cr3/Cr2+ | −0.4 V |
| Mn3+/Mn2+ | +1.5 V |
| Fe3+/Fe2+ | +0.8 V |
Use this data to comment upon:
The stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+.
Write the formula of an oxo-anion of Chromium (Cr) in which it shows the oxidation state equal to its group number
Complete and balance the following chemical equations
`Fe^(2+) + MnO_4^(-) + H^+ ->`
Give reasons Iron has the higher enthalpy of atomization than that of copper.
Transition metals with lowest melting point is ______.
The orientation of an atomic orbital is governed by
Give reason for the following statement:
[Ti(H2O)]3+ is coloured while [Sc(H2O)6]3+ is colourless.
Complete the following reaction and justify that it is a disproportionation reaction:
\[\ce{3MnO^{2-}4 + 4H^+ -> \underline{}\underline{}\underline{}\underline{} + \underline{}\underline{}\underline{}\underline{} + 2H2O}\]
Which of the following ions has the electronic configuration 3d6?
(Atomic number: Mn = 25, Co = 27, Ni = 28)
