Advertisements
Advertisements
Question
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.
Advertisements
Solution
(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.
Explanation:
In d-block elements, for heavier elements, the higher oxidation states are more stable. Hence, \[\ce{Mo(VI)}\] and \[\ce{W(VI)}\] are more stable than \[\ce{Cr(VI)}\]. That’s why, \[\ce{Cr(VI)}\] in the form of dichromate is a stronger oxidizing agent in acidic medium whereas \[\ce{MoO3}\] and \[\ce{WO3}\] are not.
APPEARS IN
RELATED QUESTIONS
Complete the following chemical equation
8MnO4- + 3S2O32- + H2O →
Complete the following equations : 2 Na2CrO4 + 2 H + →
Complete the following chemical equation
Cr2O72- + 3Sn2+ + 14H+ →
Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.
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.
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.
Write the formula of an oxo-anion of Manganese (Mn) in which it shows the oxidation state equal to its group number.
E0 value for Mn3+ Mn2+ couple is much more positive than that for Cr3-/ Cr2-.
Using IUPAC norms, write the formula of potassium trioxalatochromate(III).
Which of the following reactions are disproportionation reactions?
(a) \[\ce{Cu^{+} -> Cu^{2+} + Cu}\]
(b) \[\ce{3MnO^{-}4 + 4H^{+} -> 2MnO^{-}4 + MnO2 + 2H2O}\]
(c) \[\ce{2KMnO4 -> K2MnO4 + MnO2 + O2}\]
(d) \[\ce{2MnO^{-}4 + 3Mn^{2+} + 2H2O -> 5MnO2 + 4H^{+}}\]
\[\ce{KMnO4}\] acts as an oxidising agent in alkaline medium. When alkaline \[\ce{KMnO4}\] is treated with \[\ce{KI}\], iodide ion is oxidised to ______.
The product formed upon heating methyl bromide with potassium tert-butoxide is
Why \[\ce{HCl}\] should not be used for potassium permanganate titrations?
Potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride, gives brown-red vapours of ______.
Complete the following ionic equation:
\[\ce{Cr2O^{2-}7 + 2OH^- ->}\]
In the two tetrahedral structures of dichromate ion, ______.
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
