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प्रश्न
How would you account for the following:
Cobalt (II) is stable in aqueous solutions, but in the presence of complexing reagents, it is easily oxidised.
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उत्तर
In the presence of complexing reagents, the crystal field stabilization energy is greater than the third ionization enthalpy of cobalt. Thus, Co (II) is easily oxidized to Co (III).
संबंधित प्रश्न
Why do interstitial compounds have higher melting points than corresponding pure metals?
Calculate magnetic moment of `Fe_((aq))^(2+) ion (Z=26).`
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element has the highest m.p?
Why do the transition elements have higher enthalpies of atomisation?
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
Predict which of the following will be coloured in the aqueous solution?
Ti3+, V3+, Cu+, Sc3+, Mn2+, Fe3+ and Co2+. Give reasons for each.
What are alloys?
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?
Give reasons: Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
Two metallic elements A and B have the following standard oxidation potentials: A = 0·40v B = - 0·80v. What would you expect if element A was added to an aqueous salt solution of element B? Give a reason for your answer.
Transition metals with highest melting point is ____________.
Transition elements show high melting points. Why?
Answer the following question:
Which element of the first transition series has highest second ionisation enthalpy?
Answer the following question:
Which element of the first transition series has lowest enthalpy of atomisation?
Give reasons for the following statement:
Transition metals and most of their compounds show paramagnetic behaviour.
Which of the following ions acts as a typical transition metal ion?
The disproportionation of \[\ce{MnO^{2-}_4}\] in acidic medium resulted in the formation of two manganese compounds A and B. If the oxidation state of Mn in B is smaller than that of A, then the spin-only magnetic moment (µ) value of B in BM is ______. (Nearest integer)
Complete the following reaction and justify that it is a disproportionation reaction:
\[\ce{3MnO^{2-}4 + 4H^+ -> \underline{}\underline{}\underline{}\underline{} + \underline{}\underline{}\underline{}\underline{} + 2H2O}\]
Consider the following standard electrode potential values:
\[\ce{Sn^{2+}_{ (aq)} + 2e^- -> Sn_{(s)}}\]; E0 = −0.14 V
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\]; E0 = +0.77 V
What is the cell reaction and potential for the spontaneous reaction that occurs?
Match List-I with List-II.
| List-I | List-II |
| A. Haber process | I. Fe catalyst |
| B. Wacker oxidation | II. PdCl2 |
| C. Wilkinson catalyst | III. [(PPh3)3RhCl] |
| D. Ziegler catalyst | IV. TiCl4 with Al(CH3)3 |
Choose the correct answer from the options given below:
