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प्रश्न
Explain why Cu+ ion is not stable in aqueous solutions?
Out of Cu+ and Cu2+, which ion is unstable in aqueous solution and why?
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उत्तर
\[\ce{Cu^{2+}_{ (aq)}}\] is more stable than \[\ce{Cu^{+}_{ (aq)}}\]. This is because copper has a higher second ionization enthalpy, but ΔhydH for \[\ce{Cu^{2+}_{ (aq)}}\] is more negative than that for \[\ce{Cu^{+}_{ (aq)}}\], so it compensates more for the second ionization enthalpy of copper. Thus many copper (I) compounds are unstable in aqueous solution and are disproportionated as follows:
\[\ce{2Cu^{+}_{ (aq)} -> Cu^{2+}_{ (aq)} + Cu_{(s)}}\]
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संबंधित प्रश्न
Why do interstitial compounds have higher melting points than corresponding pure metals?
Account for the following:
Cu+ ion is unstable in aqueous solution.
Account for the following:
Zn is not considered as a transition element.
Account for the following:
E° value for the Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+.
Which is a stronger reducing agent, Cr2+ or Fe2+ and why?
Why are Mn2+ compounds more stable than Fe2+ towards oxidation to their +3 state?
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
Write down the number of 3d electrons in the following ion:
Cu2+
Indicate how would you expect the five 3d orbitals to be occupied for this hydrated ion (octahedral).
Write the factors which are related to the colour of transition metal ions.
Give reasons: Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
Give reasons for the following:
The transition metals generally form coloured compounds.
Which among the following transition metal has the lowest melting point?
Metallic radii of some transition elements are given below. Which of these elements will have highest density?
| Element | \[\ce{Fe}\] | \[\ce{Co}\] | \[\ce{Ni}\] | \[\ce{Cu}\] |
| Metallic radii/pm | 126 | 125 | 125 | 128 |
EΘ of Cu is + 0.34V while that of Zn is – 0.76V. Explain.
Match the catalysts given in Column I with the processes given in Column II.
| Column I (Catalyst) | Column II (Process) |
| (i) \[\ce{Ni}\] in the presence of hydrogen | (a) Zieglar Natta catalyst |
| (ii) \[\ce{Cu2C12}\] | (b) Contact process |
| (iii) \[\ce{V2O5}\] | (c) Vegetable oil to ghee |
| (iv) Finely divided iron | (d) Sandmeyer reaction |
| (v) \[\ce{TiCl4 + Al (CH3)3}\] | (e) Haber's Process |
| (f) Decomposition of KCIO3 |
When a chromite ore (A) is fused with sodium carbonate in free excess of air and the product is dissolved in water, a yellow solution of compound (B) is obtained. After treatment of this yellow solution with sulphuric acid, compound (C) can be crystallised from the solution. When compound (C) is treated with KCl, orange crystals of compound (D) crystallise out. Identify A to D and also explain the reactions.
Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:
(activation energy, Threshold energy, increased, lowered, partially, full, d-d transition, Benzoic acid, benzaldehyde)
Only those transition metal ions will be coloured which have ______ filled d-orbitals facilitating ______.
The electrode potential of M2+/M of 3d-series elements shows the positive value for ______.
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)
Account for the following:
Eu2+ with electronic configuration [Xe]4f76s2 is a strong reducing agent.
