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Redox Reactions
Assignment ( 2 marks each )
1. Justify that the reaction :
2Cu2O (s) + Cu2S (s) → 6Cu (s) + SO2 (g)
is a redox reaction, identify the species oxidised/reduced.
2. Construct the cell in which the given reactions are taking place, which
electrode shall act as anode (negative electrode) and which one as cathode
(positive electrode) :
(a) ZnSO4 + CuSO4 = ZnSO4 + Cu
(b) Cu + 2AgNO3 = Cu(NO3)2 + 2Ag
3. Four metals A, B, C, D have their standard reduction potential values equal
to +.80, −0.76, −0.12 and 0.34 V respectively. Arrange them in decreasing
order of their electropositive character.
[Hint : The metal which has high negative value of standard reduction
potential possess great tendency to lose electron(s), that is, it is highly
electropositive.]
4. Given the standard electrode potential :
K+/K = −293 V
:
Ag+/Ag = 0.80 V
Hg2+/Hg = +0.79 V :
Mg2+/Mg = −2.37 V
Cr3+/Cr = −0.74 V
Arrange these in increasing reducing power.
5. Define the term redox couple. Write a practical application of redox couple.
6. (a) What are the functions of salt bridge in an electrochemical cell ?
(b) What is standard hydrogen electrode ?
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