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Question
Explain why:
(i) Mn2+ is more stable than Fe2+ towards oxidation to +3 state.
(At. no. of Mn = 25, Fe = 26)
(ii) Transition elements usually form coloured ions.
(iii) Zr and Hf exhibit similar properties.
(At. no. of Zr = 40, Hf = 72)
Solution
(i) This is because Mn2+(3d5) has an extra stable electronic configuration but Fe2+(3d6) does not.
(ii) This is due to the presence of impaired electrons in their (n-1) d – orbitals.
(iii) This is due to lanthanide contraction or ineffective shielding but intervening 4f- electrons in Hf.
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RELATED QUESTIONS
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element shows only +3 oxidation state?
|
`E_((M^(2+)/M)` |
Cr | Mn | Fe | Co | Ni | Cu |
| -0.91 | -1.18 | -0.44 | -0.28 | -0.25 | -0.34 |
From the given data of E0 values, answer the following questions :
(1) Why is `E_(((Cu^(2+))/(Cu)))` value exceptionally positive
(2) Why is `E_(((Mn^(2+))/(Mn)))` value is highly negative as compared to other elements
(3) Which is the stronger reducing agents Cr2+ or Fe2+ ? Give Reason.
Out of Mn3+ and Cr3+, which is more paramagnetic and why ?
(Atomic nos. : Mn = 25, Cr = 24)
In what way is the electronic configuration of the transition elements different from that of the non-transition elements?
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
Account for the following :
Ti4+ is colourless whereas V4+ is coloured in an aqueous solutions.
When an oxide of manganese (A) is fused with KOH in the presence of an oxidising agent and dissolved in water, it gives a dark green solution of compound (B). Compound (B) disproportionates in neutral or acidic solution to give purple compound (C). An alkaline solution of compound (C) oxidises potassium iodide solution to a compound (D) and compound (A) is also formed. Identify compounds A to D and also explain the reactions involved.
Which of the following ions acts as a typical transition metal ion?
Consider the following standard electrode potentials (E° in volts) in aqueous solution:
| Element | M3+/M | M+/M |
| Al | - 1.66 | +0.55 |
| Tl | + 1.26 | -0.34 |
Based on these data, which of the following statements is correct?
Consider the following standard electrode potential values:
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\], E0 = +0.77 V
\[\ce{MnO^{-4}_{ (aq)} + 8H^+ + 5e^- -> Mn^{2+}_{ (aq)} + 4H2O_{(l)}}\], E0 = +1.51 V
What is the cell potential for the redox reaction?
