d(ΔG) = ΔH − TΔS
ΔG = −nFE
−2× 96500 × 1.015 = −21800 − 300 ΔS
−195895 + 21800 = −300 ΔS
−22105300 = ΔS
ΔS = −73.53JK−1mol−1