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प्रश्न
Transition metals can act as catalysts because these can change their oxidation state. How does \[\ce{Fe(III)}\] catalyse the reaction between iodide and persulphate ions?
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उत्तर
Reaction between iodide and persulphate ions is:
\[\ce{2I^{-} + S2O^{2-}8 ->[Fe(III)] I2 + 2SO^{2-}4}\]
Role of \[\ce{Fe(III)}\] ions:
\[\ce{2Fe^{3+} + 2I^{-} -> 2Fe^{2+} + I2}\]
\[\ce{2Fe^{2+} + S2O^{2-}8 -> 2Fe^{3+} + 2SO^{2-}4}\]
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संबंधित प्रश्न
What are interstitial compounds?
Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?
Which is a stronger reducing agent, Cr2+ or Fe2+ and why?
Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.
Give reasons: Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
Transition elements show high melting points. Why?
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
Reactivity of transition elements decreases almost regularly from Sc to Cu. 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 |
Answer the following question:
Which element of the first transition series has lowest enthalpy of atomisation?
On the basis of the figure given below, answer the following questions:
- Why Manganese has lower melting point than Chromium?
- Why do transition metals of 3d series have lower melting points as compared to 4d series?
- In the third transition series, identify and name the metal with the highest melting point.
Which does not belong to first transition series?
The given graph shows the trends in melting points of transition metals:
Explain the reason why Cr has the highest melting point and manganese (Mn) has a lower melting point.
A pair of coloured ions is ______.
Explain the use of different transition metals as catalysts.
Give a reason for the following:
Zinc, cadmium and mercury are considered as d-block elements but not regarded as transition elements.
Give a reason for the following:
Transition metals possess a great tendency to form complex compounds.
Give a reason for the following.
Some transition metals and their compounds get attracted towards the magnetic field.
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 ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
Decide which of the following atomic numbers are the atomic numbers of the inner transition elements:
29, 59, 74, 95, 102, 104
