A. Calculate 
of the following reaction at 298K:
Given: 
B. Using the 
values of A and B, predict which is better for coating the surface of iron 
to prevent corrosion and why?
Given:
a) The cell reaction is :
2Cr + 3Fe2+→ 2Cr3+ + 3Fe
To calculate the emf of the cell, we apply the Nernst equation:
Where n = number of electrons involved in the cell reaction
∴ n = 6
E°cell = 0.261 V (given)
Fe2+ = 0.01M , Cr3+ = 0.01M (given)
By putting R = 8.314 JK-1 mole-1
T = 298K
F = 96500 coulombs
We get,
Ecell = 0.2807 V
Thus, the emf of the cell at 298 K is 0.2807 V
b) A is better for coating the surface of iron to prevent corrosion, because its E0 value (-2.3V) is more negative.
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