Page 2 - Microsoft Word - Lesson note-2(Redox reaction)

3+
Example-(i) Balance Cr2O7 + Fe → Cr + Fe in acidic medium.
3+
2-
2+
+
2-
2+
3+
Ans-Balanced equation is Cr2O7 + 6Fe + 14H → 2Cr + 6Fe + 7H2O
3+
2-
Example-(ii) Balance MnO4 + S2O3 → MnO2 + SO4 in basic medium.
-
-
-
-
2-
-
Balanced equation is 8MnO4 + 3S2O3 + 2H2O → 8MnO2 + 6SO4 + 2OH
Assignment:
Q1. Balance the following equations by oxidation number method in
acidic medium.
3+
+
-
2-
Cr2O7 + I + H → Cr + I2 + H2O
Q2. Balance the following equations by oxidation number method in
basic medium.
-
-
-
MnO4 + I + H2O → MnO2 + I2 + OH
Q3. Balance the following equations by ion-electron method in acidic
medium.
3+
+
2-
Cr2O7 + H2S + H → Cr + S + H2O

Q4. Balance the following equations by ion-electron method in acidic
medium.
2-
-
+
MnO4 + C2O4 + H → MnO2 + CO2 + H2O

Home assignment:
Q1. Balance the following equations by oxidation number method in
acidic medium.

+
MnO4 + NO2 + H → MnO2 + I2 + H2O
-
-

Q2. Balance the following equations by oxidation number method in
basic medium.
-
MnO4 + I + H2O → MnO2 + IO3 + OH
-
-
-
Q3. Balance the following equations by ion-electron method in acidic
medium.
MnO4 + S + H → Mn + S + H2O
-
2-
2+
+

Q4. Balance the following equations by ion-electron method in acidic
medium.

MnO4 + SO3 + H → Mn + I2 + H2O
-
2-
2+
+