Refer to the galvanic cell below (the contents of cell are written beneath each

Question

Refer to the galvanic cell below (the contents of cell are written beneath each comp each h rtmcni Pf 0.10 M MnoM 0.40 M Cr 3+ 0.20 M Mn? 0.30 M Cr20 0.010 M H 0.010 M H The standard reduction potentials are as follows: MnO, Mn 1.51 V E 1.33 V 22) When current is allowed to flow, which specics is oxidized? CO Mno4 D) Mn 2+ E) H+ 23) When current is allowed to flow, which species is reduced? A) Cr20,2- C) MnO. Mn2+ E) H+ 24) Calculate the Eocel 33 25) Balance the above redox reaction using half reaction method in acidic solution. STw [Spointsl Mno. Cr20 Cra a g e

Explanation / Answer

(3) (C) Electrolysis is the process of making of non spontaneous reaction by applying current.

(4) (B) For a spontaneous reaction deltaG should be negative.

SInce deltaG = - n F Ecell

to be deltaG negative , Ecell must be positive

(7) (E) Salt bridge is useful to maintain electrical neutrality in both compartments.

(25) MnO4- + Cr2O72- -----------> Mn2+ + Cr3+

     +7 -2       +6 -2                    +2        +3

Oxidation state of Mn is decreased form + 7 to +2 , so it undergoes reduction.

Oxidation state of Cr is decreased from +6 to +3, so, it undergoes reduction.

In any redox reaction there must be an oxidation as well as a reduction half reactions. But no way to two reduction or two oxidation reaction to occur.

So, this type of reaction is not possible.

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