Balance the Redox reactions

(R) stands for half equation of reduction.

(O) stands for half equation of oxidation.

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(a)

(R): MnO4- +8H+ + 5e- → Mn2+ + 4H2O

(O): VO2+ + H+ → V(OH)4+ + e-

(R) + 5 x (O):

MnO4- + 5VO2+ + 13H+ → Mn2+ + 5V(OH)4+ + 4H2O

=====
(b)

(R): Cr2O72- + 14H+ + 6e- → 2Cr3+ + 7H2O

(O): U4+ + 2H2O → UO22+ + 4H+ + 2e-

(R) + 3 x (O):

Cr2O72- + 3U4+ + 2H+ → 2Cr3+ + 3UO22+ + H­2O

=====
(c)

(R): 2IO3- + 12H+ + 10e- → I2 + 6H2O

(O): 2I- → I2 + 2e-

(R) + 5 x (O):

2IO3- + 10I- + 12H+ → 6I2 + 6H2O

The simplest overall equation is:

IO3- + 5I- + 6H+ → 3I2 + 3H2O

=====
(d)

(R): HPO32- + 3OH- → PO43- + 2H2O + 2e-

(O): MnO4- + e- → MnO42-

(R) + 2 x (O):

HPO32- + 2MnO4- + 3OH- → PO43- + 2MnO42- + 2H2O
=

2008-07-10 15:20:08 補充：
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