delta_G_standard = -RT ln(K) = -nFE_standard. These three quantities are interconnected: if delta_G < 0, then K > 1 and E > 0 (spontaneous forward reaction). If delta_G > 0, then K < 1 and E < 0. At equilibrium: delta_G = 0 (not delta_G_standard). delta_G_standard tells us about standard conditions; delta_G tells us about actual conditions. delta_G = delta_G_standard + RT ln(Q). When Q < K: delta_G < 0 (forward). When Q > K: delta_G > 0 (reverse). When Q = K: delta_G = 0 (equilibrium).