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प्रश्न
Write balanced chemical equations for the conversion of `CrO_4^(2-)` to `Cr_2O_7^(2-)` in acidic medium and `Cr_2O_7^(2-)` to `CrO_4^(2-)`
in basic medium.
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उत्तर
`K_2Cr_2O_7 + 2KOH -> 2K_2CrO_4 + H_2O`
`2K_2CrO_4 + 2HCl -> K_2Cr_2O_7 + 2KCl + H_2O`
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संबंधित प्रश्न
Account for the following:
Cu+ ion is unstable in aqueous solution.
Why are Mn2+ compounds more stable than Fe2+ towards oxidation to their +3 state?
Compare the stability of +2 oxidation state for the elements of the first transition series.
How would you account for the following:
The d1 configuration is very unstable in ions.
Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following point:
Electronic configurations
Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid-state?
\[\ce{KMnO4}\] acts as an oxidising agent in acidic medium. The number of moles of \[\ce{KMnO4}\] that will be needed to react with one mole of sulphide ions in acidic solution is ______.
Highest oxidation state of manganese in fluoride is \[\ce{+4 (MnF4)}\] but highest oxidation state in oxides is \[\ce{+7 (Mn2O7)}\] because ______.
Which of the following ions show higher spin only magnetic moment value?
(i) \[\ce{Ti^3+}\]
(ii) \[\ce{Mn2+}\]
(iii) \[\ce{Fe2+}\]
(iv) \[\ce{Co3+}\]
Why does copper not replace hydrogen from acids?
Explain why does colour of KMnO4 disappear when oxalic acid is added to its solution in acidic medium.
EΘ of Cu is + 0.34V while that of Zn is – 0.76V. Explain.
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
Match the properties given in Column I with the metals given in Column II.
| Column I (Property) | Column II (Metal) | |
| (i) | An element which can show +8 oxidation state | (a) \[\ce{Mn}\] |
| (ii) | 3d block element that can show | (b) \[\ce{Cr}\] |
| upto +7 oxidation state | (c) \[\ce{Os}\] | |
| (iii) | 3d block element with highest melting point | (d) \[\ce{Fe}\] |
Match the properties given in Column I with the metals given in Column II.
| Column I (Property) | Column II (Metal) | |
| (i) | Element with highest second ionisation enthalpy |
(a) \[\ce{Co}\] |
| (ii) | Element with highest third ionisation enthalpy |
(b) \[\ce{Cr}\] |
| (iii) | \[\ce{M}\] in \[\ce{M(CO)6}\] is | (c) \[\ce{Cu}\] |
| (iv) | Element with highest heat of atomisation |
(d) \[\ce{Zn}\] |
| (e) \[\ce{Ni}\] |
Assertion (A): Cu cannot liberate hydrogen from acids.
Reason (R): Because it has positive electrode potential.
Why are fluorides of transition metals more stable in their higher oxidation state as compared to the lower oxidation state?
A metallic ion 'M' reacts with chloride ion to form white precipitate which is readily soluble in aqueous ammonia. Identify 'M'?
The standard electrode potentials of four elements A, B, C and D are – 3.05, – 1.66, – 0.40 and + 0.80. The highest chemical reactivity will be exhibited by
The complex showing a spin-span magnetic moment of 2.82 B.M. is :-
On adding NaOH, solution to the aqueous solution of K2CrO7 the colour of the solution changes from
The electrode potential of M2+/M of 3d-series elements shows the positive value for ______.
Which of the following characteristics of transition metals is associated with their catalytic activity?
Account for the following:
Ce4+ is a strong oxidising agent.
In order to protect iron from corrosion, which one will you prefer as a sacrificial electrode, Ni or Zn? Why? (Given standard electrode potentials of Ni, Fe and Zn are -0.25 V, -0.44 V and -0.76 V respectively.)
Write the ionic equation for reaction of KI with acidified KMnO4.
A pair of coloured ions is ______.
The compounds of \[\ce{Ti^4+}\] ions are colourless due to ______.
