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Karnataka Board PUCPUC Science 2nd PUC Class 12

Use the data given in below find out which option the order of reducing power is correct. E0cr2O12-Cr3+ = 1.33 V E0Cl2Cl- = 1.36 V E0MnO4-MN2+ = 1.51 V E0Cr3+Cr = – 0.74 V

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Question

Use the data given in below find out which option the order of reducing power is correct.

`"E"_("Cr"_2"O"_7^(2-)//"Cr"^(3+))^⊖`= 1.33 V `"E"_("Cl"_2//"Cl"^-)^⊖` = 1.36 V

`"E"_("MnO"_4^-//"Mn"^(2+))^⊖` = 1.51 V `"E"_("Cr"^(3+)//"Cr")^⊖` = - 0.74 V

Options

  • \[\ce{Cr^{3+} < Cl– < Mn^{2+} < Cr}\]

  • \[\ce{Mn^{2+} < Cl– < Cr^{3+} < Cr}\]

  • \[\ce{Cr^{3+} < Cl– < Cr_2O_7^{2–} < MnO^{-}4}\]

  • \[\ce{Mn2+ < Cr3+ < Cl– < Cr}\]

MCQ
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Solution

\[\ce{Mn^{2+} < Cl– < Cr^{3+} < Cr}\]

Explanation:

Lower the value of standard reduction potential greater will be the reducing power.

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Chapter 3: Electrochemistry - Exercises [Page 35]

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NCERT Exemplar Chemistry Exemplar [English] Class 12
Chapter 3 Electrochemistry
Exercises | Q I. 10. | Page 35

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Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half-reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half-cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If \[\ce{E^0_{cell}}\] is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as Cu2+. This was first formulated by Faraday in the form of laws of electrolysis.
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