a) Derive Eh-pH equations based on the progressive oxidation of Mn to form oxides starting with metallic Mn. b) Plot these equations in coordinates of Eh and pH, add the stability limits of water (from class), and label all fields c) Is metallic Mn stable at the surface of Earth? Gfo (kcal/mol) Mn2+ = -54.52 Manganosite= -86.74 Pyrolusite= -111.18 Hausmannite= -306.7 Manganite = -133.2 H2O = -56.687