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प्रश्न
Give an example and suggest a reason for the following feature of the transition metal chemistry:
The lowest oxide of transition metal is basic, the highest is amphoteric/acidic.
Account for the following:
The lowest oxide of transition metal is basic whereas the highest oxide is amphoteric or acidic.
Account for the following:
The lowest oxide of transition metal is basic, and the highest is acidic.
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उत्तर १
The lowest oxide has the lowest oxidation state of the transition metal. Hence, the oxide is basic and tends to react with acids to get oxidised to attain a higher oxidation state. Whereas the highest oxides are formed in higher oxidation states. As a result, these oxides are amphoteric acidic. For example, MnO is basic, whereas Mn2O7 is acidic.
उत्तर २
In the case of a lower oxide of a transition metal, the metal atom has some electrons present in the valence shell of the metal atom that are not involved in bonding. As a result, it can donate electrons and behave as a base, whereas in the higher oxide of a transition metal, the metal atom does not have an electron in the valence shell for donation. As a result, it can accept electrons and behave as an acid.
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संबंधित प्रश्न
When chromite ore FeCr2O4 is fused with NaOH in presence of air, a yellow-coloured compound (A) is obtained, which on acidification with dilute sulphuric acid gives a compound (B). Compound (B) on reaction with KCl forms an orange coloured crystalline compound (C).
(i) Write the formulae of the compounds (A), (B) and C.
(ii) Write one use of compound (C).
Complete the following chemical equation
8MnO4- + 3S2O32- + H2O →
Complete the following equation :
`2MnO_4^(-)+6H^++5NO_2^(-)rarr`
Complete the following equation : MnO4- + 8H+ + 5e- →
Give an example and suggest a reason for the following feature of the transition metal chemistry:
The highest oxidation state is exhibited in oxoanions of a metal.
E0 value for Mn3+ Mn2+ couple is much more positive than that for Cr3-/ Cr2-.
Write the chemical equation for the preparation of 4 KMnO from 2. MnO Why does purple colour of acidified permanganate solution decolourise when it oxidises Fe2- to Fe3+ ?
Using IUPAC norms, write the formula of potassium trioxalatochromate(III).
\[\ce{KMnO4}\] acts as an oxidising agent in alkaline medium. When alkaline \[\ce{KMnO4}\] is treated with \[\ce{KI}\], iodide ion is oxidised to ______.
Generally transition elements and their salts are coloured due to the presence of unpaired electrons in metal ions. Which of the following compounds are coloured?
(i) \[\ce{KMnO4}\]
(ii) \[\ce{Ce(SO4)2}\]
(iii) \[\ce{TiCl}\]
(iv) \[\ce{Cu2 Cl2}\]
In the form of dichromate, \[\ce{Cr (VI)}\] is a strong oxidising agent in acidic medium but \[\ce{Mo (VI)}\] in \[\ce{MoO3}\] \[\ce{and W (VI)}\] in \[\ce{WO3}\] are not because:
(i) \[\ce{Cr(VI)}\] is more stable than \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\].
(ii) \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\] are more stable than \[\ce{Cr(VI)}\].
(iii) Higher oxidation states of heavier members of group-6 of transition series are more stable.
(iv) Lower oxidation states of heavier members of group-6 of transition series are more stable.
Why \[\ce{HCl}\] should not be used for potassium permanganate titrations?
Complete the following ionic equation:
\[\ce{Cr2O^{2-}7 + 2OH^- ->}\]
Indicate the steps in the preparation of \[\ce{K2Cr2O2}\] from chromite ore.
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
