Refer to the galvanic cell below (the contents of cell are written beneath each
ID: 520269 • Letter: R
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 eExplanation / 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.