Question

Balance
the
following
redox
reactions
by
ion
–
electron
method
:


a)
Cr2O7
(aq)2–
+
SO3
2-(g)
→
Cr3+
(aq)
+
SO42–
(aq)
(in
acidic
solution)​

Answer 1

Answer:

2Cr2O7(aq)-2 +8H+ (aq) +3SO3(aq) 3-→

2Cr+3(aq) + 3SO4(aq)2- + 4H2O

Explanation:

concept: in acidic solution , in reaction distinguish which compound get oxidised and get reduced and then do their balancing

Explanation:

Cr2O7(aq)2- gets reduced into Cr3+(aq) and SO3 2-(g) get oxidised into SO42–(aq)

(i)Reduced part

Cr2O7(aq)2. →. Cr+3

Cr2O7(aq)2. →. . 2Cr+3

Cr2O7(aq)2. →. 2Cr+3 +7H2O

(Cr2O7(aq)2+ 14H+ + 6e-→. 2Cr+3 +7H2O )*1

(ii) oxidised part

SO3 2- + →SO4 2-

SO3 2- + H2O→SO4 2-

(SO3 2- + H2O→SO4 2-+2H+. +2e-)*3

3SO3 2- + 3H2O→3SO4 2-+6H+. +6e-

after combining both final reaction

2Cr2O7(aq)-2 +8H+ (aq) +3SO3(aq) 3-→

2Cr+3(aq) + 3SO4(aq)2- + 4H2O