Question

The standard electrode potential E? and its temperature coefficient (dE?/dT)p for a cell
are 2V and ?5?10?4 VK?1 at 300K respectively. The cell reaction is Zn(s) +
Cu2+(aq)? Zn2+(aq) + Cu(s). The standard reaction enthalpy (?rH?) at 300K is
_________________ kJ/mol (F= 96485 C mol-1
)

Answer 1

Correct Question :

The standard electrode potential Eº and its temperature coefficient (dEº/dT) for a cell are 2V and –5 × 10∧–4 VK∧–1 at 300K respectively. The cell reaction is Zn(s) + Cu2+(aq)→ Zn2+(aq) + Cu(s). The standard reaction enthalpy (ΔrHº) at 300K in kJmol–1 is,  

[F = 96,485 Cmol–1]

Answer :

The standard reaction enthalpy (?rH?) at 300K is -412.8 kJ/mol

ΔH° = ΔG° + TΔS°

ΔH° = -nFE° + T {nF x dE° / dT}

= -2 x 96485 x 2 + 300 { 2 x 96485 x (-5 x 10∧-4)}

= -412.8 kJ/mol