5-Hydroxy-1,4-naphthoquinone (juglone)

E = –93(mV), ionic strength = ~0.1, pH = 7

Reference compound: O₂; (1 mol dm^–3)
Reference E: –155 mV
Co-solute: HCO₂^–

Concentrations used to estimate equilibrium constant; data at other pH values, also with 1.1.5