Question

The e.m.f. of cell Zn | ZnSO₄ | | CuSO₄ | Cu at 25°C is 0.03 V and the temperature coefficient of e.m.f. is −1.4 × 10⁻⁴ V/K. The heat of reaction for the change taking place inside the cell is ______ kJ/mol.

विकल्प

• 13.842

• −13.842

• 14.287

• −14.287

Answer 1

The e.m.f. of cell Zn | ZnSO₄ | | CuSO₄ | Cu at 25°C is 0.03 V and the temperature coefficient of e.m.f. is −1.4 × 10⁻⁴ V/K. The heat of reaction for the change taking place inside the cell is −13.842 kJ/mol.

Explanation:

According to Gibb's Helmholtz equation,

Heat of reaction ∆H, given as

T = 273 + 25 = 298 K, n = 2, F = 96500 C, E = 0.03 CV

`((δ"E")/(δ"T"))_"p"` = −1.4 × 10⁻⁴ V/K

∆H = `"nF"["T"((δ"E")/(δ"T"))_"p" - "E"]`

= 2 × 96500 [298 × (−1.4 × 10⁻⁴)] − 0.03

= –13842 J

= –13.842 kJ/mol