The standard electrode potential E o and its temperature coefficient dE dT for a cell are 2   V and -…

The standard electrode potential Eo and its temperature coefficient dEdT for a cell are 2V and -5×10-4 V K-1 at 300 K, respectively. The reaction is Zn s+Cu2+ aqZn2+ aq+Cu s. The standard reaction enthalpy ΔrH- at 300K in mol-1 is 

[Use R=8 J K-1 mol-1 and F=96,500 Cmol-1]

  1. -412.8
  2. 206.4
  3. -384.0
  4. 192.0

Solution

ΔG=-nFEcell=-2×96500×2=-386kJ
ΔS=nFdEdT=2×96500×-5×10-4 J degree celcious-1
=-96.5 J

At 298 K,

S=298×-96.5 J=-28.757kJ
At constant temperature T=248 K and pressure,

ΔG=ΔH-S

ΔH=ΔG+S

=-386-28.757=-414.75-412.8

Asked in: JEE Main 2019 (12 Jan Shift 1)

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