Class 12th Chemistry 2017 Set3 Outside Delhi Board Paper Solution
(a) The cell in which the following reactions occurs:
Eocell = 0.236 V at 298 K. Calculate the standard Gibbs energy of the cell reaction. (Given : 1F = 96,500 C mol-1)
(b) How many electrons flow through a metallic wire if a current of 0.5 A is passed for 2 hours ? (Given : 1F = 96,500 C mol-1)
(a) E0 cell = 0.236 V
∆Gθ = -NFEθ
n=2, F=96500C
∆G0 = 2 × (96500 C) × (0.236 V)
= -45548 J
or
= -45.55 KJ
∆Gθ = -2303 RT log KC
logKc = ∆G0 / 2.303 RT
= - 45.55 / (2.303 × 8.314 × 10-3 × 298)
= 7.983
Kc = antilog (7.983)
= 9.62 × 107
(b) Current, I = 0.5 A
Time, t = 2 hours
In sec we get Time,
t = 2 × 60 × 60 s = 7200 s
Charge : Q = I × t
= 0.5 A × 7200 s
= 3600 Coulombs
Number of electrons = total charge / charge on 1 electrons
= 3600 / (1.6 × 1019)
= 2.25 × 1022 electrons
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