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Chemistry of Transition And Inner-Transition Elements
In the extraction of zinc from zinc how oxide is converted to zinc.
(i) Give an equation to show how zinc oxide is converted to zinc.
(ii) How is impure zinc finally electro-refined.
(i)ZnO+C → Zn+CO
(ii) Impure zinc is electro-refined by using impure zinc as an anode, pure zinc as a cathode and an aqueous solution of ZnSO4 as electrolyte containing a little H2SO4.
Cathode → Zn2+ + 2e- → Zn
Anode → Zn → Zn2+ + 2e‒
Explain why:
(i) Transition elements form coloured compounds.
(ii) Interhalogen compounds are more reactive than their constituent elements.
(iii) Cu+ is diamagnetic but Cu2+ is paramagnetic. (Z = 29).
(i) Due to the presence of unpaired electrons in d-orbitals and empty d-orbitals. Gives rise to possibility of d-d transition.
(ii) X—Y bonds are weaker than X—X and Y—Y bonds/Polar nature of X—Y bonds/Less overlapping of orbitals in X—Y bond.
(iii) Cu1+ has no unpaired electrons, hence diamagnetic. Cu2+ has unpaired electrons, hence paramagnetic. [Cu→29→1s2 , 2s2 , 2p6 , 3s2 , 3p6 , 4s1 , 3d10]
[Cu1+→28→1s2 , 2s2 , 2p6 , 3s2 , 3p6 , 3d10; d-orbital fully filled]
all electron in Cu1+ is paired.
[Cu2+→27→1s2 , 2s2 , 2p6 , 3s2 , 3p6 , 4s1 , 3d9 ; d-orbital partially filled 1 unpaired electron].
Give one example (equation) of a homogeneously catalysed reaction and name the catalyst.
Hydrolysis of ethyl acetate to give ethanol and acetic acid is catalyzed by dilute H2SO4.
What is the electronic configuration of chromium atom (Z = 24)? Give a reason for your answer.
The electronic configuration of Cr (24) is 1s2, 2s2p6, 3s2p6d5,4s1.
This is because an electronic configuration with half-filled and completely filled orbitals is more stable. Cr has 3d orbitals half filled configuration which is more stable than normally expected i.e 3d4 4s2.
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Mock Test Series
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