For the reaction of Chromium in the +6 oxidation state: K2Cr2O7 (aq) ACIDIC + Fe

Question

For the reaction of Chromium in the +6 oxidation state: K2Cr2O7 (aq) ACIDIC + FeSO4 (aq)
Use the table provided to answer.
Oxidation Half Reaction: ? Overall Balanced Redox Reaction: ?
This isting includes all the with your hall-reactions occurring in a given test Select the ap- to help you identity the propriate conditions acidic, neutral or basic pH.Note that the net ionic form of each halt-neaction is include spectator lons (such as Na and Ci-), which are not shown in this listing and which do not affect the E" values Standard (1 M) acid solution Zn2++ 2 e- Zn(s) 2 H +2eH2(9) Cu2+ + e- Cu. Cu2+ + 2e- Cu(s) 12(aq) + 2e-21. 02(g) + 2H+ + 2e-H2O2 Fe3+ + e- Fe2+ -0.76V 0.00V 0.15V 0.34V 0.54V 0.695 V 0.77 V 1.23V 1.78 V 1.92V H202 + 2H+ + 2 e-2H2O Neutral solution (interpolated values) Cu2+ + e- Cu+ 0.15 V 0.27 V 0.27 V 0.34 V 0.54 V 0.77 V 1.36 V 1.92 V O(9)+2H +2e-HO2 Cu2+ + 2 e- Cu(s) k(aq) + 2e--+21- Fe3+ + e- Fe2+ H202 + 2H. + 2 e--+2H20 Co3+ + e- CO2 + Standard (1 M) base solution Fe(OH)s(s) +Fe(OH)2(s)+ OH Cu(OH)2(s) + 2 e- Cu(s) + 2 OH- -0.56 V -0.22V -0.15 V -0.13 V -0.08V 0.17 V 0.54 V 0.94 V -02(g) +2H2O +2e-H2O2 + 2 OH - Cr042-+ 4 H2O + 3 e- Cr(OH)3(s) + 5 OH- 2 Cu(OH)2(s) + 2e- Cu2O(s) + 2 OH-+ HO Co(OH)s(s)+Co(OH)2(s)+ OH- 12(aq) + 2e--+2|- -H202 + 2e-2OH

Explanation / Answer

The oxidation half reaction is

Fe+2 ------------->Fe+3 + e , E0 = -0.77V

The reduction half reaction is

Cr2O7-2 + 14H+ +6e- -----------------> 2Cr+3 + 7H2O E0 = 1.23 V

thus the overall reaction is

Cr2O7-2 + 14H+ + 6Fe+2 -----------------> 6Fe+3 + 2Cr+3 + 7H2O Ecell = 1.23-0.77=0.46 V

the molecular balanced overall reaction is

K2Cr2O7 + 6 FeSO4 + 7H2SO4 ------------> Cr2(SO4)3 + K2SO4 + 3Fe2(SO4)3 + 7H2O

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