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प्रश्न
Describe the oxidising action of potassium dichromate and write the ionic equation for its reaction with iodide.
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उत्तर
Potassium dichromate acts as a strong oxidizing agent. It is used as a primary standard in volumetric analysis. The oxidation action of dichromate ion in an acidic medium can be represented as follows –
\[\ce{Cr2O^2-_7 + 14H+ + 6e^- -> 2Cr^{3+} + 7H2O}\] (E– = 1.33 V)
The iodide ion (I−) is oxidised to I2 by the acidified solution of K2Cr2O7.
Reaction:
\[\ce{Cr2O^2-_7 + 14H+ + 6I- -> 2Cr^{3+} + 7H2O + 3I2 ^}\]
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संबंधित प्रश्न
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Give reasons for the following:
The transition metals generally form coloured compounds.
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(i) \[\ce{Cr}\]
(ii) \[\ce{Co}\]
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(iv) \[\ce{Ni}\]
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Match List - I with List - II.
| List - I | List - II | ||
| (A) | [Fe(CN)6]3− | (i) | 5.92 BM |
| (B) | [Fe(H2O)6]3+ | (ii) | 0 BM |
| (C) | [Fe(CN)6]4− | (iii) | 4.90 BM |
| (D) | [Fe(H2O)6]2+ | (iv) | 1.73 BM |
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