Thermochemistry

Question

Calculate the ΔGO (in kJ/mol) for the following reaction at 25.0℃.

2Cr+3(aq)+2Mg(s)→2Cr(s)+3Mg+2(aq)

Answer 1

∆Gº = -nFEº_cell

2Cr³⁺(aq) + 3Mg(s) ==> 2Cr(s) + 3Mg²⁺(aq) ... balanced equation

6 mols electrons are transferred = n

F = 96,500 C/mol e-

Eºcell = -0.74 + 2.38 = 1.64 V (calculated from standard reduction potentials for Mg²⁺ and Cr³⁺)

Solving for ∆Gº, we have...

∆Gº = -(6)(96,500)(1.64) = -949,560 coulomb-volts = -949,560 Joules = -950 kJ